Consider the diffusion of oxygen through a low-density polyethylene (LDPE) sheet 15 mm thick. The pressures of oxygen at the two faces are 2000 kPa and 150 kPa, which are maintained constant. Assuming conditions of steady state, what is the diffusion flux [in [(cm3 STP)/cm2-s] at 298 K

Answers

Answer 1

The diffusion flux of oxygen through the LDPE sheet can be calculated using Fick's first law of diffusion:

J = -D*(delta C/delta x)

where J is the diffusion flux, D is the diffusion coefficient of oxygen in LDPE, delta C is the difference in oxygen concentration across the sheet, and delta x is the thickness of the sheet.

Assuming ideal gas behavior, we can use the following expression to convert between partial pressure and concentration:

C = (P/(R*T))

where C is the concentration in mol/cm^3, P is the partial pressure in Pa, R is the gas constant (8.314 J/mol-K), and T is the temperature in Kelvin.

Using the given pressures and the ideal gas law, we can calculate the concentration difference across the sheet as follows:

delta C = (P1/(RT)) - (P2/(RT))

delta C = ((2000 kPa)*1000 Pa/kPa)/(8.314 J/mol-K * 298 K) - ((150 kPa)*1000 Pa/kPa)/(8.314 J/mol-K * 298 K)

delta C = 0.0412 mol/cm^3

The diffusion coefficient of oxygen in LDPE at 298 K is approximately 1.4x10^-9 cm^2/s.

Plugging in the given values, we get:

J = -D*(delta C/delta x)

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Related Questions

a 0.047 m solution of the salt nab has a ph of 9.36. calculate the ph of a 0.011 m solution of hb. (assume kw = 1.00 ✕ 10−14.)

Or, what is the Kb of HB?

Answers

To calculate the pH of a 0.011 m solution of HB, we need to first determine the Kb of HB. HB is a weak base, so we can use the equation Kb = Kw/Ka, where Ka is the acid dissociation constant. Since HB is the conjugate base of the weak acid H2B, we can use the acid dissociation constant of H2B, which is Ka = 1.4 x 10^-9. Therefore, Kb = 7.14 x 10^-6.

Now, we can use the relationship between pH and pOH to determine the pH of the 0.011 m solution of HB. Since pOH = -log[OH-] and [OH-] = sqrt(Kb*[HB]), we can calculate [OH-] as follows:

[OH-] = sqrt(7.14 x 10^-6 * 0.011) = 2.96 x 10^-4 M

And since pH + pOH = 14, we can calculate the pH as:

pH = 14 - pOH = 14 - (-log[OH-]) = 11.53

Therefore, the pH of a 0.011 m solution of HB is approximately 11.53.

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Determine the pH of a solution prepared by dissolving 0.75 mol of NH3 and 0.25 mol of NH4Cl in a liter of solution. Kb

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i determine the ph of a solution

The pH of the solution is 8.18.

The pH of the solution, we need to first determine the concentration of OH- ions in the solution. We can do this by finding the concentration of NH3 that reacts with water to form OH- ions using the Kb value for [tex]NH_3[/tex].

The reaction between  [tex]NH_3[/tex] and water can be represented as follows:

[tex]NH_3[/tex] + [tex]H_2O[/tex] ⇌ [tex]NH_4[/tex]+ + OH-

The equilibrium constant expression for this reaction is:

Kb = [ [tex]NH_4[/tex]+][OH-] / [ [tex]NH_3[/tex]]

We can use the stoichiometry of the reaction to find the concentration of OH- ions produced by  [tex]NH_3[/tex]:

0.75 mol  [tex]NH_3[/tex] / 1 L solution x 1 L solution = 0.75 M  [tex]NH_3[/tex]

Kb for  [tex]NH_3[/tex] = 1.8 x  [tex]10^{-6[/tex]

[tex]NH_3[/tex] + [tex]H_2O[/tex] ⇌ [tex]NH_4[/tex]+ + OH-

Initially, [ [tex]NH_3[/tex]] = 0.75 M, and [ [tex]NH_4[/tex]+] = [OH-] = 0.

At equilibrium, let x be the concentration of  [tex]NH_4[/tex]+ and OH-. Therefore, the concentration of NH3 remaining at equilibrium will be (0.75 - x) M, and the concentration of OH- ions produced by NH3 will be x M.

Using the Kb expression, we can write:

Kb = [ [tex]NH_4[/tex]+][OH-] / [ [tex]NH_3[/tex]]

1.8 x  [tex]10^{-6[/tex] = x / (0.75 - x)

x = 1.5 x  [tex]10^{-6[/tex] M

Therefore, the concentration of OH- ions produced by  [tex]NH_3[/tex] in the solution is 1.5 x  [tex]10^{-6[/tex] M.

pH = 14 - pOH

pOH = -log[OH-] = -log(1.5 x [tex]10^{-6[/tex]) = 5.82

pH = 14 - 5.82 = 8.18

Therefore, the pH of the solution is 8.18.

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A balloon carries 40.0 gallons of liquid propane (density 0.5005 g/L). What volume of CO2 and H2O gas is produced by the combustion of this propane

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The answer cannot be determined without temperature and pressure conditions.

What volume of CO2 and H2O gas is produced by the combustion of 40.0 gallons of liquid propane?

To determine the volume of CO2 and H2O gas produced by the combustion of 40.0 gallons of liquid propane, we need to consider the balanced chemical equation for the combustion reaction of propane (C3H8):

C3H8 + 5O2 -> 3CO2 + 4H2O

Volume of liquid propane = 40.0 gallonsDensity of liquid propane = 0.5005 g/L

First, we need to convert the volume of liquid propane to its mass:

Mass of liquid propane = Volume of liquid propane × Density of liquid propane

Next, we can use the stoichiometry of the balanced chemical equation to determine the molar ratio between propane and the products (CO2 and H2O).

From the balanced equation, we can see that for every 1 mole of propane, 3 moles of CO2 and 4 moles of H2O are produced.

Finally, we can calculate the moles of propane based on its mass and convert them to moles of CO2 and H2O.

From the moles of CO2 and H2O, we can then determine their volumes using the ideal gas law.

Since the volume of liquid propane is given in gallons, it is necessary to convert it to liters before proceeding with the calculations.

Please note that the temperature and pressure conditions are required to accurately calculate the volume of gases using the ideal gas law.

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What is the name of the enzyme that catalyzes the reaction where the third carbon (C3) of glucose is converted to CO2. Imagine that the C3 of glucose is isotopically labeled (13C) and follow the carbon through the reactions of glycolysis, PDH, and TCA where applicable.

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The enzyme that catalyzes the reaction where the third carbon (C₃) of glucose is converted to CO₂ is pyruvate dehydrogenase (PDH). PDH is a multi-enzyme complex that converts pyruvate (a three-carbon molecule) to acetyl-CoA (a two-carbon molecule), releasing CO₂ and producing NADH in the process.

If the C₃ of glucose is isotopically labeled with 13C, it will be incorporated into the pyruvate molecule during glycolysis. This labeled pyruvate will then be converted to labeled acetyl-CoA by PDH, with the labeled carbon atom being released as CO₂. The labeled carbon will then be incorporated into the TCA cycle through the formation of citrate, and it will undergo a series of oxidation-reduction reactions before ultimately being released as CO₂ in the final step of the cycle.

Overall, the labeled carbon will be released as CO₂ twice during the metabolism of glucose: once during PDH and once during the TCA cycle. The fate of the labeled carbon can be traced through the metabolic pathways using isotopic labeling techniques such as isotopic tracer analysis.

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Tetrahydrofolate (THF) is generated from dihydrofolate (DHF) by dihydrofolate reductase (DHFR) and uses ___________ as the reducing agent.

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Tetrahydrofolate (THF) is generated from dihydrofolate (DHF) by dihydrofolate reductase (DHFR) and uses NADPH as the reducing agent.

Tetrahydrofolate (THF) is an important cofactor in many biological reactions, including the synthesis of DNA, RNA, and amino acids. It is generated from dihydrofolate (DHF) by the enzyme dihydrofolate reductase (DHFR), which reduces the two carbonyl groups of DHF to alcohol groups.

This reduction reaction requires a source of reducing equivalents, which in biological systems is usually provided by the cofactor NADPH (nicotinamide adenine dinucleotide phosphate, reduced form).

NADPH is an electron carrier molecule that plays a crucial role in many cellular processes, including biosynthesis, oxidative stress response, and immune function.

It is generated from NADP+ (nicotinamide adenine dinucleotide phosphate, oxidized form) through the action of enzymes such as glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase. In the case of the reduction of DHF to THF, NADPH donates two electrons to DHFR, which in turn uses them to reduce DHF to THF.

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Part A Choose the mixture that has the highest melting point. A. 0.100 m C6H12O6 B. 0.100 m AlCl3

C. 0.100 m Bal2 D. 0.100 m KI E. They all have the same melting point.

Answers

The mixture with the highest melting point is option B, 0.100 m [tex]AlCl_3[/tex].

This is because [tex]AlCl_3[/tex] is an ionic compound, meaning it has strong electrostatic forces between its ions. These forces require a higher amount of energy to break apart during the melting process, resulting in a higher melting point. In contrast, options A, C, and D are molecular compounds that have weaker intermolecular forces and thus lower melting points. It is important to note that the concentration of the mixture does not affect the melting point, as it only refers to the amount of solute present in a solvent. Therefore, all options have the same concentration, but the type of compound and its intermolecular forces determine the melting point.

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Identify the density of the beverages of cola and apple juice with the given table. create a graph similiar to the one in the example and estimate their sugar contents from the calibration curve. (the exmaple is just here to show you this should be a line graph)

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Density is a measure of how much mass is contained in a certain volume of a substance. By using the mass and volume values of the cola and apple juice, we can determine their respective densities.

With this information, we can create a calibration curve by plotting density against sugar content. This curve will help us estimate the sugar content of each beverage based on its density. The estimation is done by finding the point of intersection between the density value of each beverage and the curve. This approach is useful for determining the sugar content of various beverages, which is an important factor to consider when making dietary choices.
 To estimate the sugar content, we need to look at the y-axis of the calibration curve, which represents sugar content, and find the corresponding point for the density of each beverage on the x-axis. The point where the two lines intersect will give us an estimate of the sugar content.

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what step in michaelis menten kinetics determines overall rate

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The step in Michaelis-Menten kinetics that determines the overall rate is the formation and breakdown of the enzyme substrate complex (ES complex).

This step is characterized by a rapid equilibrium between the ES complex and the free enzyme and substrate. The rate of formation of the ES complex is proportional to the concentration of both the enzyme and the substrate, whereas the rate of breakdown of the ES complex is proportional to the concentration of the ES complex. The overall rate is determined by the rate of formation of the ES complex, as this is the rate-limiting step in the reaction. Enzyme are biological catalysts that speed up chemical reactions in living organisms. They are proteins made up of chains of amino acids, and their unique three-dimensional shape allows them to bind to specific molecules, called substrates, and facilitate chemical reactions. Enzymes play crucial roles in metabolism, digestion, and other cellular processes, and their activity can be regulated by factors such as pH, temperature, and inhibitors. Deficiencies or abnormalities in enzyme function can lead to various diseases and disorders.

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What volume, in mL, of concentrated 12 M hydrochloric acid would you need to use in order to prepare 800.0 mL of a 0.100 M H2SO4(aq) solution

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You would need to measure out 6.67 mL of your concentrated 12 M HCl solution to prepare 800.0 mL of a 0.100 M H₂SO₄(aq) solution.


M₁ V₁  = M₂V₂

where M₁ is the concentration of your concentrated HCl solution, V₁  is the volume of concentrated HCl solution you'll need to use, M₂ is the concentration of your desired H2SO4 solution, and V₂ is the final volume of your solution (in this case, 800.0 mL).

First, let's solve for V₁ :

M₁V₁ = M₂V₂

12 M x V₁ = 0.100 M x 800.0 mL

V₁ = (0.100 M x 800.0 mL) / 12 M

V₁ = 6.67 mL

So you would need to measure out 6.67 mL of your concentrated 12 M HCl solution to prepare 800.0 mL of a 0.100 M H₂SO₄(aq) solution.

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An irreversible, gas phase reaction proceeds to a certain conversion in a PFR operating isothermally, isobarically, and at steady state. If all other reactor conditions are held constant, what happens to the conversion if we reduce the pressure

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The answer to the question is that if the pressure is reduced while all other reactor conditions are held constant, the conversion of the irreversible, gas phase reaction in the PFR will decrease.

The reaction rate of a gas phase reaction is directly proportional to the partial pressure of the reactants. Therefore, reducing the pressure of the system will decrease the partial pressure of the reactants and consequently decrease the reaction rate. As a result, the conversion of the reaction will decrease. It is important to note that this is only true for an irreversible reaction, as a reversible reaction may shift towards the side with fewer moles of gas in response to a decrease in pressure.

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What is the pressure of a gas, in millimeters of mercury, in a sample container connected to a mercury-filled, open-ended manometer if the level of mercury in the arm connected to the atmosphere is 3.41 cm higher than the arm connected to the sample container and if atmospheric pressure is 99.54 kPa

Answers

The  pressure of the gas in the sample container connected to the manometer is 25.6 mmHg. First, we need to convert the height difference of the mercury levels from centimeters to millimeters. There are 10 mm in 1 cm, so the height difference is 3.41 cm x 10 mm/cm = 34.1 mm.

We need to find the pressure difference between the gas in the sample container and the atmospheric pressure. This can be found by subtracting the height difference of the mercury levels from the atmospheric pressure. 99.54 kPa - (34.1 mm / 760 mmHg/kPa) = 99.54 kPa - 0.045 = 99.495 kPa ,Now we can use the conversion factor of 1 mmHg = 0.133 kPa to convert the pressure difference from kilopascals to millimeters of mercury. 99.495 kPa x (1 mmHg/0.133 kPa) = 748.5 mmHg .


First, convert the atmospheric pressure from kPa to mmHg. 1 kPa is approximately equal to 7.50062 mmHg. So, 99.54 kPa × 7.50062 (mmHg/kPa) ≈ 746.99 mmHg. Convert the difference in mercury levels from cm to mm. 1 cm is equal to 10 mm. So, 3.41 cm × 10 (mm/cm) = 34.1 mm. The level of mercury in the arm connected to the atmosphere is 3.41 cm higher than the arm connected to the sample container, meaning the gas pressure is lower than the atmospheric pressure. Subtract the difference in mercury levels from the atmospheric pressure to find the gas pressure: 746.99 mmHg - 34.1 mm = 726.4 mmHg.
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How long (in hours) must a current of 5.0 amperes be maintained to electroplate 60 g of calcium from molten CaCl2

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A current of 5.0 amperes must be maintained for approximately 32 hours to electroplate 60 g of calcium from molten CaCl2.

The amount of calcium that can be electroplated can be calculated using Faraday's laws of electrolysis, which state that the amount of substance deposited on an electrode is directly proportional to the amount of electrical charge passed through the electrode.

The equation to calculate the amount of substance deposited during electrolysis is:

mass (in grams) = (current in amperes x time in seconds x molar mass) / (valence x 96500)

Where the valence is the number of electrons required to deposit one mole of the substance, and 96500 is the Faraday constant.

For calcium, the molar mass is 40.08 g/mol and the valence is 2.

So, to electroplate 60 g of calcium from molten CaCl2, we can rearrange the equation as:

time (in seconds) = (mass x valence x 96500) / (current x molar mass)

time (in seconds) = (60 g x 2 x 96500) / (5.0 A x 40.08 g/mol)

time (in seconds) = 115,060 seconds

Converting seconds to hours, we get:

time (in hours) = 115,060 seconds / 3600 seconds per hour

time (in hours) ≈ 32 hours

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if energy can flow in and out of the system to maintain a constant temperature during the process, what can you say about the entropy

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If energy can flow in and out of the system to maintain a constant temperature during the process, the entropy of the system may increase, decrease, or remain constant.


Entropy is a measure of the degree of randomness or disorder in a system.

In a process where energy can flow in and out to maintain a constant temperature, the change in entropy depends on the specific process occurring.

If the process leads to an increase in randomness, the entropy will increase. If the process leads to a decrease in randomness, the entropy will decrease.

If the randomness remains constant, the entropy will remain unchanged.


Summary: The entropy of a system with constant temperature during a process can increase, decrease, or remain constant, depending on the degree of randomness in the system as the process occurs.

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A mixture of the amino acids leucine (Leu), glutamate (Glu), and arginine (Arg) is added to a cation exchange column at neutral pH. In what order will they elute from a cation exchange column

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The order of elution for the given amino acids from a cation exchange column at neutral pH is: Leu, Glu, Arg.

The elution order of amino acids from a cation exchange column depends on the net charge of the amino acid at the pH of the elution buffer. At neutral pH, the carboxyl group (-COOH) of amino acids is not fully ionized, while the amino group (-NH3+) is fully ionized, resulting in a net positive charge for the amino acid.

Among the given amino acids, leucine (Leu) is a nonpolar amino acid and does not have any ionizable side chains. Therefore, it does not have any net charge at neutral pH and will not bind to the cation exchange column. It will pass through the column and elute first.

Arginine (Arg) is a basic amino acid with a positively charged guanidinium group (-NH=C(NH2)2) in its side chain. At neutral pH, the guanidinium group is fully ionized, resulting in a net positive charge. Therefore, Arg will bind to the cation exchange column through ionic interactions and will elute last.

Glutamate (Glu) is an acidic amino acid with a negatively charged carboxyl group (-COO-) in its side chain. At neutral pH, the carboxyl group is only partially ionized, resulting in a net negative charge. Therefore, Glu will have a weaker interaction with the cation exchange column compared to Arg and will elute in between Leu and Arg.

Therefore, the order of elution for the given amino acids from a cation exchange column at neutral pH is: Leu, Glu, Arg.

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g How many different tripeptides can be synthesized using no more than one molecule of each of 3 different amino acids

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The number of different tripeptides that can be synthesized using no more than one molecule of each of 3 different amino acids are 27

To determine the number of different tripeptides that can be synthesized using no more than one molecule of each of 3 different amino acids, we need to use the formula:

n^r

Where n represents the number of different options for each position and r represents the number of positions.

In this case, we have 3 options for each of the 3 positions (since we are using no more than one molecule of each amino acid). Therefore:

3³ = 27

So, there are 27 different tripeptides that can be synthesized using no more than one molecule of each of 3 different amino acids.

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A 1.00 g sample of glucose, C6H 1206, is burned in a bomb calorimeter, the temperature of the calorimeter rises by 9.40 0 C. What is the heat capacity of the calorimeter

Answers

According to the question the heat capacity of the calorimeter is 0.449 J/°C

What is calorimeter?

A calorimeter is a device used to measure the amount of heat generated or absorbed during a chemical or physical process. It is used in a variety of laboratory experiments to measure the heat of a reaction or the specific heat of a material. The calorimeter is typically composed of a thermally insulated container with a thermometer and a stirrer to mix the reaction and measure the temperature change. The container is usually filled with a known amount of water, and the heat produced or absorbed during the reaction is calculated by measuring the temperature change of the water.

The heat capacity of the calorimeter can be calculated using the equation, q = mcΔT,
where q is the heat energy transferred,
m is the mass of the sample,
c is the heat capacity of the calorimeter, and
ΔT is the change in temperature.
Therefore, the heat capacity of the calorimeter can be calculated as follows:
c = q/(mΔT) = (1.00 g x 4.184 J/g°C) / (9.40°C) = 0.449 J/°C.

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4.- Fluorine gas initially at 12 L, .9 atm, and 35°C undergoes a change so that its final volume and temperature are 7 L and 25°C. What is its final pressure? Moles remain the same.

Answers

To solve this problem, we can use the combined gas law:
(P1 x V1) / (T1) = (P2 x V2) / (T2)
Where P1, V1, and T1 are the initial pressure, volume, and temperature, and P2, V2, and T2 are the final pressure, volume, and temperature.
We are given the initial values for P1, V1, and T1, and the final values for V2 and T2. We need to solve for P2.Substituting the given values into the equation, we get:
(0.9 atm x 12 L) / (35°C) = (P2 x 7 L) / (25°C)
Simplifying and solving for P2, we get:
P2 = (0.9 atm x 12 L x 25°C) / (35°C x 7 L)
P2 = 1.23 atm

Therefore, the final pressure of the fluorine gas is 1.23 atm.
To find the final pressure of the fluorine gas, you can use the combined gas law formula, which is:
(P1 × V1) / T1 = (P2 × V2) / T2
Given initial conditions: P1 = 0.9 atm, V1 = 12 L, and T1 = 35°C
Final conditions: V2 = 7 L, and T2 = 25°C
First, convert the temperatures from Celsius to Kelvin:
T1 = 35°C + 273.15 = 308.15 K
T2 = 25°C + 273.15 = 298.15 K


Now, plug the values into the combined gas law formula and solve for P2 (final pressure):
(0.9 atm × 12 L) / 308.15 K = (P2 × 7 L) / 298.15 K
Rearrange the equation to solve for P2:
P2 = (0.9 atm × 12 L × 298.15 K) / (308.15 K × 7 L)
P2 ≈ 1.106 atm
The final pressure of the fluorine gas is approximately 1.106 atm.

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When a 15.8 mL sample of a 0.490 M aqueous hydrocyanic acid solution is titrated with a 0.413 M aqueous sodium hydroxide solution, what is the pH after 28.1 mL of sodium hydroxide have been added?

pH =

When a 28.5 mL sample of a 0.460 M aqueous nitrous acid solution is titrated with a 0.395 M aqueous potassium hydroxide solution, what is the pH at the midpoint in the titration?

pH =

A 16.0 mL sample of a 0.374 M aqueous acetic acid solution is titrated with a 0.351 M aqueous barium hydroxide solution. What is the pH at the start of the titration, before any barium hydroxide has been added?

pH =

Answers

For the first question:

Write the balanced chemical equation for the reaction between hydrocyanic acid (HCN) and sodium hydroxide (NaOH):

HCN + NaOH → NaCN + H2O

Calculate the initial number of moles of HCN in the solution:

n(HCN) = M(HCN) x V(HCN) = 0.490 M x 0.0158 L = 0.007742 mol HCN

Determine which reactant is the limiting reactant:

n(NaOH) = M(NaOH) x V(NaOH) = 0.413 M x 0.0281 L = 0.01162 mol NaOH

Based on this calculation, NaOH is in excess and HCN is the limiting reactant.

Calculate the number of moles of HCN remaining after the reaction is complete:

n(HCN) = n(initial) - n(NaOH) = 0.007742 mol - 0.01162 mol = -0.003878 mol

Note that this is a negative value, which means that all of the HCN has been consumed and there is excess NaOH remaining.

Calculate the concentration of NaOH remaining in the solution:

M(NaOH) = n(NaOH) / V(total)

V(total) = V(HCN) + V(NaOH) = 0.0158 L + 0.0281 L = 0.0439 L

M(NaOH) = 0.01162 mol / 0.0439 L = 0.264 M

Calculate the concentration of hydroxide ions in the solution:

[OH-] = M(NaOH) x (V(NaOH) / V(total)) = 0.264 M x (0.0281 L / 0.0439 L) = 0.169 M

Calculate the pOH of the solution:

pOH = -log[OH-] = -log(0.169) = 0.771

Calculate the pH of the solution:

pH + pOH = 14.00

pH = 14.00 - pOH = 14.00 - 0.771 = 13.229

Therefore, the pH of the solution after 28.1 mL of NaOH have been added is 13.229.

For the second question:

Write the balanced chemical equation for the reaction between nitrous acid (HNO2) and potassium hydroxide (KOH):

HNO2 + KOH → KNO2 + H2O

Calculate the initial number of moles of HNO2 in the solution:

n(HNO2) = M(HNO2) x V(HNO2) = 0.460 M x 0.0285 L = 0.01311 mol HNO2

Determine the volume of KOH required to reach the midpoint of the titration:

At the midpoint of the titration, half of the HNO2 has been converted to NO2-. Therefore, the number of moles of KOH required to reach this point is equal to half the initial number of moles of HNO2:

n(KOH) = 0.5 x n(HNO2) = 0.5 x 0.01311 mol = 0.006556 mol KOH

The volume of KOH required can be calculated using the concentration of KOH:

V(KOH) = n(KOH) / M(KOH) = 0.006556 mol / 0.395 M = 0.

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A gas cylinder containing 6.38 mol of neon has a pressure of 491 mm Hg at 295 K. If 3.22 mol of helium is added to this cylinder, at constant temperature and volume, what will be the pressure in the cylinder

Answers

The pressure in the cylinder after adding the helium is 0.873 atm.

We can use the ideal gas law to solve this problem. The ideal gas law states that:

PV = nRT

Since the temperature and volume of the gas are constant, we can simplify the ideal gas law to:

P1V = n1RT

P2V = (n1 + n2)RT

where P1 is the initial pressure of the gas, n1 is the initial number of moles of gas (6.38 mol of neon), n2 is the number of moles of gas added (3.22 mol of helium), and P2 is the final pressure of the gas.

P2 = (n1 + n2)RT/V

   = [(6.38 mol) + (3.22 mol)] * (0.0821 L*atm/mol*K) * (295 K) / V

   = 9.60 atm / V

To find V, we can use the fact that the volume is constant:

P1V = P2V

V = P1V/P2

 = (491 mm Hg) * (1 atm/760 mm Hg) * (22.4 L) / (9.60 atm)

 = 11.0 L

Now we can substitute V = 11.0 L into the expression for P2:

P2 = 9.60 atm / 11.0 L

   = 0.873 atm

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Which structures are composed of aqueous compartments enclosed by a lipid bilayer and can be used to deliver chemicals to cells?a. vesicleb. micellec ribosomed. chloroplaste lysosome

Answers

The structures that are composed of aqueous compartments enclosed by a lipid bilayer and can be used to deliver chemicals to cells are vesicles and micelles. The correct option is A and B.

Vesicles are small sacs made up of a lipid bilayer membrane that encloses an aqueous compartment, and they are involved in various cellular processes such as transport, secretion, and storage. These structures can be used to deliver chemicals to cells by fusing with the cell membrane and releasing their contents into the cell.

Micelles, on the other hand, are small spherical aggregates of amphipathic molecules such as lipids, detergents, or surfactants that form a lipid bilayer-like structure in water. They are also used to deliver chemicals to cells by facilitating the transport of hydrophobic molecules across the cell membrane. Micelles can solubilize hydrophobic drugs and help them penetrate the cell membrane, making them an effective drug delivery system.

Ribosomes and chloroplasts are not enclosed by a lipid bilayer and are not involved in the delivery of chemicals to cells. Lysosomes are also enclosed by a lipid bilayer but are involved in the breakdown and recycling of cellular waste, rather than delivering chemicals to cells.

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13) What is the final concentration of a solution prepared by using 75.0 mL of 18.0 M H2SO4 to prepare 500. mL of solution

Answers

The final concentration of the solution is 2.7 M H₂SO₄

We can use the formula:

M1V1 = M2V2

where M1 is the initial concentration, V1 is the initial volume, M2 is the final concentration, and V2 is the final volume.

In this case, we know that the initial volume (V1) is 75.0 mL and the initial concentration (M1) is 18.0 M. We also know that the final volume (V2) is 500.0 mL.

To find the final concentration (M2), we can rearrange the formula:

M2 = (M1V1) / V2

Plugging in the numbers, we get:

M2 = (18.0 M * 75.0 mL) / 500.0 mL

M2 = 2.7 M

Therefore, the final concentration of the solution is 2.7 M.

Thus, we can find the final concentration of a solution by using the formula M1V1 = M2V2 and rearranging it to solve for M2. In this specific problem, the final concentration is 2.7 M when 75.0 mL of 18.0 M H2SO4 is used to prepare 500.0 mL of solution.

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What Wittig reagent would produce the desired product? W TER IL o Ph₃P=CH₂ HI o PhzP=CHCH2CH2CH3 o Ph3P=C(CH3)2 o Ph₃P =CHCH₃

Answers

The Wittig reagent is an organophosphorus compound that is used to produce alkenes from carbonyl compounds. It contains a phosphorus ylide, which reacts with the carbonyl compound to form a new carbon-carbon double bond. In order to determine which Wittig reagent would produce the desired product, we need to consider the structure of the carbonyl compound and the desired product.

In this case, we are looking for the Wittig reagent that would produce a product with the following structure: TER IL. This indicates that the product is a terpene with an isopropyl group. We can eliminate the Wittig reagent Ph3P=C(CH3)2, as this would produce a product with a tert-butyl group rather than an isopropyl group.

The other three Wittig reagents all have the potential to produce the desired product. Ph₃P=CH₂ is the simplest and most commonly used Wittig reagent, but it may not be the best choice in this case. HI is a strong acid, and could potentially cause unwanted side reactions. PhzP=CHCH2CH2CH3 and Ph₃P =CHCH₃ both contain longer alkyl chains, which could potentially affect the reactivity of the Wittig reagent.

Ultimately, the best Wittig reagent to use would depend on the specific carbonyl compound and reaction conditions. However, based solely on the desired product structure, PhzP=CHCH2CH2CH3 or Ph₃P =CHCH₃ would be the most likely candidates to produce the desired TER IL product with an isopropyl group.

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What reaction conditions favor the conversion of the initially-formed salt to the amide when an amine and a carboxylic acid are reacted with each other

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To favor the conversion of the initially-formed salt to the amide when an amine and a carboxylic acid are reacted with each other, you should use the following reaction conditions:

1. Apply heat: Heating the reaction mixture helps promote the formation of the amide by driving off the water formed in the reaction.

2. Use a coupling agent: Adding a coupling agent like DCC (dicyclohexylcarbodiimide) or EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) can facilitate the formation of the amide by activating the carboxylic acid group and making it more reactive.

3. Opt for a non-aqueous solvent: Using a non-aqueous solvent, such as an aprotic solvent like DMF (dimethylformamide) or DCM (dichloromethane), helps prevent the reverse reaction (hydrolysis of the amide) and promotes the formation of the desired product.

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Alcohol and alcohol-based prep solutions are volatile and flammable. When alcohol solution or volatile fumes come in contact with heat sources, they can easily cause:

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When alcohol solution or volatile fumes come in contact with heat sources, they can easily cause combustion, ignition, or fire.

How to handle alcohol safetly?

Alcohol and alcohol-based prep solutions are highly flammable and volatile. When exposed to heat sources, they can easily ignite and cause fires, explosions, and serious injury.  This is due to their low flash points,  which means it can easily ignite at room temperature. Alcohols have low flash points because they have low boiling points and high vapor pressures at room temperature.

It is crucial to handle and store these solutions properly, away from any potential sources of ignition, and to follow all safety precautions when using them. It is also important to ensure adequate ventilation in areas where alcohol fumes may be present, to prevent inhalation and health hazards.

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Classify each of the following as ionic or molecular. Drag the appropriate items to their respective bins. Reset Help Cl2O7 Cu(NO2)2 Co(C2H302) 2Al(ClO2)3 Baz (PO4)2 AsCl3 MgCO3 lonic Molecular

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Here's the classification for ionic or molecular: Ionic: Cu(NO2)2, Co(C2H3O2), 2Al(ClO2)3, Ba3(PO4)2, MgCO3 and Molecular: Cl2O7, AsCl3 in the bins.

Chemical compounds known as ionic compounds are made up of ions that are held together by electrostatic attraction. Positively charged cations and negatively charged anions are commonly produced when a metal atom donates one or more electrons to a nonmetal atom. Then, as a result of the attraction between these ions with opposing charges, a crystal lattice is created. High melting and boiling temperatures, as well as a propensity to dissolve in polar solvents like water, are characteristics of ionic compounds. They are generally bad conductors when solid, but they exhibit significant electrical conductivity when melted or dissolved in water. Ionic substances include things like magnesium oxide and sodium chloride (table salt).


1. Cl2O7 - Molecular (covalent bonding between nonmetals)
2. Cu(NO2)2 - Ionic (metal and nonmetal bonding)
3. Co(C2H3O2) - Ionic (metal and nonmetal bonding)
4. 2Al(ClO2)3 - Ionic (metal and nonmetal bonding)
5. Ba3(PO4)2 - Ionic (metal and nonmetal bonding)
6. AsCl3 - Molecular (covalent bonding between nonmetals)
7. MgCO3 - Ionic (metal and nonmetal bonding)

So, the respective bins would be:

Ionic:
- Cu(NO2)2
- Co(C2H3O2)
- 2Al(ClO2)3
- Ba3(PO4)2
- MgCO3

Molecular:
- Cl2O7
- AsCl3

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Synergistic effects of toxicants ________.Group of answer choiceshave effects of individual toxicants that tend to cancel one another outare not numerous in the natural environmentare greater than the sum of the effects of the componentsalways involve synthetic toxicants

Answers

Synergistic effects of toxicants occur when the combined effect of two or more toxicants is greater than the sum of their individual effects.

In other words, the toxicants work together in a way that amplifies their impact beyond what would be expected from their individual effects. This phenomenon is observed in both natural and synthetic toxicants and can have significant effects on human and environmental health. For example, exposure to two toxicants that individually cause mild harm might result in severe harm when combined.

It is important to consider the potential for synergistic effects when evaluating the risks associated with exposure to toxicants, as the effects of combined exposures can be difficult to predict based on the effects of individual toxicants alone.

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Synergistic effects of toxicants ________.

A) have effects of individual toxicants that tend to cancel one another out

B) typically exhibit additive effects of the individual toxicants

C) are not numerous in the natural environment

D) are greater than the sum of the effects of the components

E) always involve synthetic toxicants

When supercooled droplets freeze directly to very cold surfaces and create fine, needle-like ice crystals, the result is:

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When supercooled droplets freeze directly to very cold surfaces and create fine, needle-like ice crystals, the result is called diamond dust.

Supercooled droplets are liquid droplets that are at a temperature below their normal freezing point, but have not yet frozen due to the absence of a nucleation site or trigger for freezing. When these droplets come into contact with a very cold surface, such as a car windshield or tree branch, they can freeze instantly and form tiny ice crystals.

These ice crystals are typically very small, with diameters of less than 0.5 millimeters, and take on a needle-like or columnar shape. They can accumulate on surfaces to form a thin layer of ice, creating a beautiful and sparkling effect that resembles diamond dust.

Freezing fog and diamond dust are most commonly observed in cold, dry climates, such as polar regions or high-altitude mountain ranges. They can create hazardous conditions for travel, as they can make surfaces slippery and reduce visibility, but they can also be a beautiful and awe-inspiring natural phenomenon to witness.

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My reaction calls for 20 mol% of catalyst. If I use 15 mmol of limiting reagent, how many mmol of catalyst should I be using

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If your reaction calls for 20 mol% of catalyst and you are using 15 mmol of limiting reagent, you would need to use 3 mmol of catalyst.

To calculate this, first you need to convert the 20 mol% into a decimal fraction by dividing it by 100, which gives you 0.2.

Then, you can calculate the total amount of moles needed for the reaction by multiplying the limiting reagent (15 mmol) by the stoichiometric coefficient of the catalyst in the balanced chemical equation.

For example, if the catalyst has a coefficient of 2, then you would need a total of 30 mmol of catalyst for the reaction. Finally, you can multiply the total amount of catalyst needed by the percentage required (0.2) to find out how much you should use for your specific reaction. In this case, 30 mmol x 0.2 = 6 mmol, which is the total amount of catalyst required.

Since you only need 20 mol% of this amount, you would use 3 mmol of catalyst for the reaction.

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Now the engineering students have placed a 50 kg lump of copper at 140 C into an insulated tank containing 90 L of water. The initial temperature of the tank was 10 C. What is the entropy change of the copper for this process in kJ/K

Answers

The mass of the copper is 50 kg and the change in temperature (ΔT) is 130 C (140 C - 10 C). Therefore, the entropy change of the copper is 6.5 kJ/K (50 kg × 130 C × 0.05 kJ/K).

What is copper ?

Copper is a soft, malleable, and ductile metal that is naturally found in the Earth's crust. It is an essential element for all forms of life, and it is used in a variety of ways in the modern world. Copper is one of the oldest metals used by humans and has been used for thousands of years in the production of jewelry, coins, and statues. It is also used in the production of electrical wiring, plumbing pipes, and other components used in the construction of buildings. Copper is also used in many industrial applications, such as in the production of semiconductors, motors, and other electronic components.

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An atom has radius of 265 pm and crystallizes in a body-centered cubic unit cell. What is the volume of the unit cell

Answers

The volume of the unit cell is approximately 7.52 x 10^7 cubic picometers.

In a body-centered cubic unit cell, there are atoms located at each corner of the cube, as well as one atom located at the center of the cube.

Therefore, the total number of atoms in a body-centered cubic unit cell is 2.

To find the volume of the unit cell, we first need to determine the length of the edge of the cube. Let's assume that the radius of the atom is equal to half the length of the diagonal of the cube.

Using the Pythagorean theorem, we can find the length of the diagonal:

diagonal^2 = (2 x radius)^2 + (2 x radius)^2 + (2 x radius)^2

diagonal^2 = 12 x radius^2

diagonal = √(12) x radius

diagonal = √(12) x 265 pm = 729.77 pm

The length of the edge of the cube is equal to the diagonal divided by the square root of 3:

edge length = diagonal / √3 = 729.77 pm / √3 = 422.46 pm

The volume of the unit cell is then calculated as:

volume = edge length^3 = (422.46 pm)^3 = 75,223,562 pm^3

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