Answer:
Positively charged: Lysine, Histidine
Negatively charged: Asparagine, Phenylalanine, Glutamatic acid, Alanine, Glycine, Leucine, Aspartic acid
Explanation:
The charge of an amino acid in solution is determined by its isoelectric point, pI, which is the characteristic pH in which the net electric charge of the amino acid is zero. In solutions of pH below the isoelectric point, the amino acid has a net positive charge whereas in solutions with pH above isoelectric point, the net charge on the amino acid is negative.
In a buffer solution of pH 6.5, the following charges are present in the amino acids given:
Positively charged: Lysine (pI = 9.74), Histidine (pI = 7.59)
Negatively charged: Asparagine (pI = 5.07), Phenylalanine (pI = 5.48), Glutamatic acid (pI = 3.22), Alanine (pI = 6.01), Glycine (pI = 5.97), Leucine (pI = 5.98), Aspartic acid (pI = 2.77)
Phosphorus-32 has a half-life of 14.0 days Starting with 4.00 g of 2P how many grams will remain after 112 days?
Answer:
You'll be left with 0.25 g of phosphorus-32. The nuclear half-life of a radioactive isotope expresses the time needed for a sample of that isotope to reach half of its initial value. In your case, regardless with how much phosphorus-32 you start with, you'll be left with half of that initial mass after 14.0 days.
Explanation:
The public is not yet able to ourchase cars powered by hydrogen fuel cells because engineers have to determine how the cars perform based on which scenario
Answer:
in real-world conditions
Explanation:
Which of the following is not a technique that could be used to separate a mixture into its components?
a) stirring.
b) decanting.
c) filtration.
d) distillation.
e) none of the above.
Answer:
Mixtures can be physically separated by using methods that use differences in physical properties to separate the components of the mixture, such as evaporation, distillation, filtration and chromatography.
Explanation:
You are very much welcom
Answer:
stirring. because it will mixup together
Hydrogen can be prepared on a small scale by the hydrolysis of metal hydrides:
CaH2 + 2H20 — Ca(OH)2 + 2H2
Assign an oxidation number to each atom and verify that the total number of electrons lost is equal to the total number gained.
Answer:
Ca²⁺ + 2H⁻ + 2(2H⁺ + O²⁻) ----> Ca²⁺ + 2O²⁻ + 2H⁺ + 4H⁰
(2 electrons lost) ----> (2 electrons gained)
Explanation:
The equation of the reaction is as follows: CaH₂ + 2H₂0 —> Ca(OH)₂ + 2H₂
The oxidation numbers of each of the atoms in the molecules are as follows:
In CaH₂, calcium has an oxidation number of +2, while hydrogen has an oxidation number of -1 ; Ca²⁺, 2H⁻
In 2H₂0, hydrogen has an oxidation number of +1 while oxygen has an oxidation number of -2 ; H⁺, O²⁻
In Ca(OH)₂, calcium has an oxidation number of +2 while oxygen has an oxidation number of -2 and hydrogen has an oxidation number of +1 ; Ca²⁺, O²⁻, 2H⁺
In 2H₂, each hydrogen atom has an oxidation number of 0 ; 4 H⁰
Ca²⁺ + 2H⁻ + 2(2H⁺ + O²⁻) ----> Ca²⁺ + 2O²⁻ + 2H⁺ + 4H⁰
On the left hand side, the hydride ion gives up two electrons to become neutral hydrogen atoms.
On the right hand, two hydrogen atoms accept two electrons to form neutral atoms.
These neutral hydrogen atoms pair up to form two hydrogen gas molecules.
2. Who was the first Avenger to crumble to dust following Thanos' snap?
A. Captain America
B. Black Panther
C. Bucky Barnes
D. The Hulk
Answer:
C. bucky barnes
Explanation:
i dont know how this relates to chemistry
What is the atom inventory for the following equation after it is properly balanced? ____K2S + ____CoCl2 Imported Asset ____KCl + ____CoS
Reactants: K = 2, S = 1, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2 Reactants: K = 2, S = 2, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 1 Reactants: K = 2, S = 2, Co = 1, Cl = 2; Products: K = 2, S = 2, Co = 1, Cl = 1 Reactants: K = 2, S = 1, Co = 2, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2
Answer:
Reactants: K = 2, S = 1, Co = 1, Cl = 2; Products: K = 2, S = 1, Co = 1, Cl = 2
Explanation:
The reaction is a double replacement reaction so the anions (Cl⁻ and S²⁻) switch places.
1 K₂S + 1 CoCl₂ ⇒ 2 KCl + 1 CoS (balanced chemical equation)
On the reactants and products side, K = 2, S = 1, Co = 1, and Cl = 2.
Hope that helps.
Select the conjugate acid-base pair(s). a) HI, I b) HCHO2, SO4^2- c) CO3^2-, HCI d) PO4^3-, HPO4^2-
Answer:
PO4^3-, HPO4^2-
Explanation:
If an acid gives out a proton, the acid then changes to its corresponding base. Similarly, if a base takes in a proton, it changes to its corresponding acid. If a pair of acid and base differ only by the presence or absence of a proton, then they are referred to as a conjugate acid-base pair.
Let us look at this;
HPO4^2-(aq) ----> H^+(aq) + PO4^3-(aq)
HPO4^2- and PO4^3- differ only in the presence or absence of a proton (H^+) hence they constitute a conjugate acid-base pair.
At a fixed volume, a four-fold increase in the temperature of a gas will lead to _______ in pressure.
Answer:
Increase in pressure
Explanation:
The rise in temperature will increase the pressure of the gas.
Answer:
increase is ur answer
hope it helps u
plz mark as brainlist
The numbers of nucleons required to generate complete shells in the nucleus are called:
A. nuclear numbers
B. shell numbers
C. special numbers
D. magic numbers
Answer:
The correct answer is option D, that is, magic numbers.
Explanation:
The magic number in nuclear physics refers to the number of nucleons, that is, either neutrons or protons, distinctly, such that their alignment results in the formation of complete shells within the nucleus of the atom. As a consequence, atomic nuclei comprising a magic number of neutrons or protons are much more stable in comparison to other nuclei.
The seven most broadly known magic numbers are 2,8,20,28,50,85 and 126.
2. (2 points) Calculate the Effective Nuclear Charge for each atom. Show all of your work for full credit. Se: Br: (1 point) Which atom is larger? (This is your claim.)
Answer:
Bromine.
Explanation:
There is more nuclear charge on bromine because in bromine, there are 35 number of protons and 46 number of neutrons while in selenium, there are 34 number of protons and 45 number of neutrons. The atomic size of selenium is larger because they have lower nuclear charge as compared to bromine and we know that when we go to the left of periodic table atomic size increases which attract the electrons towards itself so the shell comes close to the nucleus and decrease occurs in atomic radius.
Atomic radius generally increases as we move
A) down a group and from right to left across a period
B) up a group and from left to right across a period
C) down a group and from left to right across a period
D) up a group and from right to left across a period
E) down a group; the period position has no effect
Answer:
C
Explanation:
Atomic radius generally increases as we move down a group and from left to right across a period
Students set up a controlled experiment. They put five
crickets in each of three identical containers. They set one
container to 15°C, one to 20°C, and one to 25°C. Then they
count the number of cricket chirps in each container
during 1 hour
What are two constants in this experiment?
A. The number of crickets in each container
B. The number of cricket chirps
O C. The kind of containers used
D. The temperature of each container
The experimental design includes the controlled, independent, and dependent variables. The number of crickets and kinds of containers is two constant. Thus, options A and C are correct.
What are control variables?Control variables are the experimental element that remains fixed and unchanged in an experimental setup. They are constant and not are directly related to the interest of the investigation topic but are known to influence the results and observations.
The control variables can influence the dependent variable of the experiment as the number of crickets in each container and the type of container can indirectly alter the outcome and the conclusion of the experiment. The number of cricket will influence the effect of the temperature and the type of container can alter the survival rate.
Therefore, in options A and C. the number of cricket and container are two constants.
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Of the following, which is the dominant (strongest) type of intermolecular force present in RbCl(s)?
A. lon-dipole
B. lonic
C. Dispersion
D. Dipole-dipole
E. Hydrogen bonding
Answer:
B. Ionic
Explanation:
RbCl is ionic compound formed from the combination of rubidium (a strongly electropositive element) and chlorine (a strongly electronegative element).
The transfer of an electron from rubidium to chlorine leads to the formation of two oppositely charged ions Rb⁺ and Cl⁻.
In a solid crystal of RbCl, the major intermolecular forces of attraction are electrostatic forces of attraction between oppositely charged ions in the molecules of the crystalline solid.
Ion-dipole attraction only occur when the solid is dissolved in a polar molecule like water. Dispersion forces as well as dipole-dipole forces, though present are weak forces and contribute very little to intermolecular attraction. Hydrogen bonding is not present as there are no hydrogen atoms in solid RbCl.
The dominant (strongest) type of intermolecular force present in RbCl(s) is ionic force (Option B).
An ion-dipole attraction refers to a type of attraction between ions and neutral dipole molecules. Ionic forces are commonly observed in different types of chemical solutions. An ion-dipole force consists of a positive/negative ion that exerts an attractive force to the negative/positive end present in a polar molecule.In conclusion, the dominant (strongest) type of intermolecular force present in RbCl(s) is ionic force (Option B).
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Which process is an example of a chemical change?
Answer:
burning of paper
melting of lead
Answer:
d- activating a glow stick
Explanation:
Glow sticks produce light through a chemical reaction.
Identify the following salts as neutral, acidic, or basic. Drag each item to the appropriate bin.
1. LiF
2. SrBr2
3. NH4CN
4. NH4Br
5. KCN
6. NH4ClO4
7. LiNO3
A. Neutral salts.
B. Acidic salts.
C. Basic salts.
Answer:
A. Neutral salts. (7, 2)
B. Acidic salts. (4, 6)
C. Basic salts. (1, 3, 5)
Explanation:
We must know where, do the ions come from. If they come from a weak acid or base, they can make hydrolysis in water, so OH⁻ and H⁺ are given to medium.
1. LiF → Li⁺ + F⁻
F⁻ + H₂O ⇄ HF + OH⁻
F⁻ can make the hydrolysis, and it gives OH⁻. Salt is basic.
2. SrBr₂ → Sr²⁺ + 2Br⁻
Both are weak and they can not hydrolyse. This salt is neutral.
3. NH₄CN → NH₄⁺ + CN⁻
Both ions are strong, so they can make the hydrolysis. The thing is, while the ammonium gives protons, the cyanide give hydroxides. To determine how's the salt, we need to compare the Ka and Kb.
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka = 5.7×10⁻¹⁰
CN⁻ + H₂O ⇄ HCN + OH⁻ Kb = 1.61×10⁻⁵
As Kb > Ka, pH is basic.
If Ka > Kb, pH would be acidic.
4. NH₄Br → NH₄ + Br⁻
Br⁻ does not hydrolize. The ammonium cation, reacts in water to give protons to medium that's why the salt will be acidic.
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka
5. KCN → K⁺ + CN⁻
K⁺ does not hydrolize. The cyanide anion, reacts in water to give hydroxides to medium that's why the salt will be basic.
CN⁻ + H₂O ⇄ HCN + OH⁻ Kb
6. NH₄ClO₄ → NH₄⁺ + ClO₄⁻
ClO₄⁻ comes from the perchlroric acid (a strong acid). It does not hydrolyze
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺ Ka
Ammonium gives H⁺ to medium so the salt is acidic.
7. LiNO₃ → Li⁺ + NO₃⁻
Both ions does not make hydrolysis. They come from a strong base and a strong acid, so they are the conjugate weak acid and base, respectively.
The salt in this case, will be neutral.
Plzzz fastttt answerrr
Which answer choices correctly describe why the number of known elements more then doubled by 1861
Answer:
Communication between scientists increased.
Technological advancements were made.
Explanation:
The options:
Metalworkers began using new metals.
Communication between scientists increased.
The American Civil War started.
Technological advancements were made.
The reasons the number of known elements more than double by 1861 would be because technological advancements have been made and communication between scientists increased.
With the advancement in technology, more equipment become available and research became more sophisticated leading to new discoveries. The new discoveries would not have made much difference if they are not adequately communicated to other scientists.
Solid sodium reacts with liquid water to form hydrogen gas according to the equation 2 Na(s) + 2 H₂O(l) → 2 NaOH(aq) + H₂(g) What is the pressure of hydrogen gas in the 20.0 L headspace of a reactor vessel when 3.34 kg sodium is reacted with excess water at 50.0°C?
Answer:
96.2 atm
Explanation:
Step 1: Write the balanced equation
2 Na(s) + 2 H₂O(l) → 2 NaOH(aq) + H₂(g)
Step 2: Calculate the moles corresponding to 3.34 kg of sodium
The molar mass of Na is 22.99 g/mol.
[tex]3.34 \times 10^{3} g \times \frac{1mol}{22.99g} =145mol[/tex]
Step 3: Calculate the moles of hydrogen formed from 145 moles of sodium
The molar ratio of Na to H₂ is 2:1. The moles of H₂ formed are 1/2 × 145 mol = 72.5 mol
Step 4: Convert the temperature to the Kelvin scale
K = °C + 273.15 = 50.0°C + 273.15 = 323.2 K
Step 5: Calculate the pressure exerted by the hydrogen gas
We will use the ideal gas equation.
[tex]P \times V = n \times R \times T\\P = \frac{n \times R \times T}{V} = \frac{72.5mol \times 0.0821atm.L/mol.K \times 323.2K}{20.0L} = 96.2 atm[/tex]
Ethyl bromide reacts with sodium methoxide to form ?
Answer:
The reactants should be ethyl bromide and sodium methoxide.
The products of the reactions are diethylether and sodium bromide.
Explanation:
When ethyl bromide, it reacts with any sodium ethoxide, it gives diethylether and also sodium bromide.
As in the sodium ethoxide, the negatively charged oxygen atom is very much reactive and it attacks on the bromine containing a carbon of the ethyl bromide and it replaces it forming methyl ethoxide. This type of reaction is sometimes known as SN2.
The compound on the right contains two functional groups. It is:________
A) an aldehyde and an ether
B) an aldehyde and an alcohol
C) a ketone and an ether
D) a ketone and an ester
E) a carboxylic acid and an ether
Answer : Option C is correct -- a ketone and an ether
Explanation:
It should be noted that Ketone and ether are the compound on the right that contain two functional groups. an aldehyde and an ether, an aldehyde and an alcohol, a ketone and an ester, and also a carboxylic acid and an ether don't contain two functional groups on the right.
Energy from radiation can cause chemical bonds to break. To break a nitrogen-nitrogen bond in N2 gas, 941kJ/mole is required.
a. Calculate the wavelength of radiation that could break the bond.
b. In what spectral range does this radiation occur?
Answer:
a) 1.269 × 10^-7 m
b) This wavelength occurs in the ultraviolet region of the electromagnetic spectrum
Explanation:
The energy required to break the bond= energy of the incident photon
E= 941 × 10^3/6.02 × 10^23 = 1.56 ×10^ -18 J
From
E= hc/λ
h= Plank's constant
c= speed of light
λ= wavelength of incident photon
λ= hc/E
λ= 6.6 ×10^-34 × 3 ×10^8/1.56 ×10^ -18 J
λ= 1.269 × 10^-7 m
b) This wavelength occurs in the ultraviolet region of the electromagnetic spectrum
Vitamin C ascorbic acid (C6F1806), is a reducing agent. One way to determine the ascorbic acid content of a sample is to mix the acid with an excess of iodine
C6H8O6 + I2 + H2O------- C6H6O6 + 2H3O + 2I-
and then titrate the iodine that did not react with the ascorbic acid with sodium thiosulfate. The balanced, net ionic equation for the reaction occurring in this titration is
I2+ 2 S2O32-(a9) —) 2 I-(a9) + S4O62-(a9)
Suppose 50.00 mL of 0.0520 M 12 was added to the sample containing ascorbic acid. After the ascorbic acid/I2 reaction was complete, the 12 not used in this reaction required 20.30 mL of 0.196 M Na2S2O3 for titration to the equivalence point. Calculate the mass of ascorbic acid in the unknown sample.
Answer:
The mass of ascorbic acid in the sample is 0.1076g
Explanation:
In other words to determine ascorbic acid in a sample:
You are adding an amount of I₂. One part is reacting with ascorbic acid and the other with sodium thiosulphate. First, we need to calculate how much thiosulphate reacts to know the iodine that reacts with thiosulphate.
I₂ that reacts with S₂O₃²⁻:
Moles S₂O₃⁻: 0.02030L × (0.196mol / L) = 3.979x10⁻³ moles S₂O₃²⁻.
As 2 moles of S₂O₃²⁻ reacts per moles of I₂, moles of I₂ are:
3.979x10⁻³ moles S₂O₃²⁻ ₓ (1 mole I₂ / 2 moles S₂O₃²⁻) = 1.989x10⁻³ moles I₂
Now, initial amount of I₂ added to the sample is:
0.0500L ₓ (0.0520mol I₂ / L) = 2.600x10⁻³ moles I₂
That means moles of I₂ that react with ascorbic acid = Moles of ascorbic acid are:
2.600x10⁻³ moles I₂ - 1.989x10⁻³ moles I₂ =
6.11x10⁻⁴ moles I₂ = Moles C₆H₈O₆.
To convert moles of substance to mass we need to use molar mass of the substance (176.12g/mol for ascorbic acid):
6.11x10⁻⁴ moles C₆H₈O₆ ₓ (176.12g / mol) =
The mass of ascorbic acid in the sample is 0.1076gOrganic molecules are defined as chemical compounds that contain ______ in distinct ratios and structures.
Answer:
The answer is: carbon
Explanation:
Organic molecules contain the chemical element carbon (C) in its structure. In this type of molecules, carbon is usually bonded to hydrogen (H), oxygen (O) and, with less frecuency, nitrogen (N). Therefore, in these molecules, carbon forms simple, double and triple bonds with itself. Examples of organic molecules that are very important in biology are carbohydrates, lipids, proteins and nucleic acids.
Cell notation will list each half-reaction:
A.) starting with the reaction at the cathode
B.) with coefficients to balance the species
C.) on each side of the salt bridge, which is represented by a double vertical line
D.) none of the above
Answer:
on each side of the salt bridge, which is represented by a double vertical line
Explanation:
While writing a cell notation, the general convention is; anode || cathode. The anode and the cathode are separated by a double line. The anode is written on the lefthand side while the cathode is written on the righthand side.
The cell notation is a shorthand representation of a cell, hence any electrochemical cell can easily be produced based on its cell diagram.
Relative to the energy stored in chemical bonds, nuclear binding energies are:_________.
a. much greater
b. much smaller
c. approximately equal
d. depends on the substance
Answer:
much greater
Explanation:
Binding energy of a nucleus is the energy evolved in the formation of a nucleus from free protons and neutrons. It is also defined as the energy that binds nucleons together in the nucleus of an atom.
The nuclear binding energy is far greater than the chemical energy stored in chemical bonds. Nuclear energy is the greatest source of energy which could be exploited to achieve various ends.
Convert
propene n to propane
⬇️
Explanation:
First convert propane to chloropropane by halogenation reaction in presence of sunlight
CH3-CH2-CH3 + Cl2 → CH3-CH2-CH2Cl + HCl
Chloropropane can be converted into propene by using alcoholic KOH
CH3-CH2-CH2Cl + alc. KOH → CH3-CH=CH2
To convert from Propene to Propan-2-ol, the addition of H2SO4 takes place in accordance with Markovnikov ‘s rule i.e.
Arrange these reactions according to increasing ΔS.
a. H 2O(g) → H 2O(l)
b. 2NO(g) → N 2(g) + O 2(g)
C. MgCO 3(s) → MgO(s) + CO2(g)
Explanation:
ΔS denotes change in entropy. Entropy is the degree of disorderliness of a system. An increasing ΔS would mean that the entropy of the products is greater than the entropy of the reactants.
Generally the trend of entropy with state of matter is given as;
Gas > Liquid > Solid (Increasing Entropy)
a. H 2O(g) → H 2O(l)
In this reaction, there is a decreasing ΔS, since we are moving from gas to liquid. This would be the last.
b. 2NO(g) → N 2(g) + O 2(g)
There is an increase in gaseous products. This is definitely an increasing ΔS reaction. This would be the first on the list.
C. MgCO 3(s) → MgO(s) + CO2(g)
The products formed are in solid and gaseous state. There is increasing ΔS but not up to reaction 2.
The order is given as;
b. 2NO(g) → N 2(g) + O 2(g)
C. MgCO 3(s) → MgO(s) + CO2(g)
a. H 2O(g) → H 2O(l)
How much heat, in kJ, will be absorbed by a 25.0 g piece of aluminum (specific heat = 0.930 J/g･°C) as it changes temperature from 25.0°C to 76.0°C?
Answer:
quantity of heat=mc*theta
=25*0.930(76-25)
=25*0.930*51
=1185.75J
=11.9kJ
Answer:
1.19kJ
Explanation:
The heat can be calculated using the specific heat capacity, mass, and the change in temperature.
q=mxcxΔT=(25.0g)×(0.930Jg⋅∘C)×(76.0−25.0∘C)=1186J
Finally, the heat can be converted from J into kJ using the metric conversion factor.
1186J×1kJ1000J=1.19kJ
Determine the standard enthalpy of formation in kJ/mol for NO given the following information about the formation of NO2 under standard conditions, and (NO2) = + 33.2 kJ/mol. Keep one decimal point. 2 NO(g) + O2(g) → 2 NO2(g) ∆Hrxn = –114.2 kJ
Answer:
90.3 kJ/mol
Explanation:
Let's consider the following thermochemical equation.
2 NO(g) + O₂(g) → 2 NO₂(g) ∆H°rxn = –114.2 kJ
We can find the standard enthalpy of formation for NO using the following expression.
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g)) - 1 mol × ΔH°f(O₂(g))
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g)) - 1 mol × 0 kJ/mol
∆H°rxn = 2 mol × ΔH°f(NO₂(g)) - 2 mol × ΔH°f(NO(g))
ΔH°f(NO(g)) = (2 mol × ΔH°f(NO₂(g)) - ∆H°rxn) / 2 mol
ΔH°f(NO(g)) = (2 mol × 33.2 kJ/mol + 114.2 kJ) / 2 mol
ΔH°f(NO(g)) = 90.3 kJ/mol
A force of 26.4lb is applied to an area of 1.71 in2. What is the pressure?
A) 15.4 lb/in2
B) 0.0648 lb/in2
C) 45.1 lb/in2
D) 22.8 lb/in2
Answer:
Pressure, P = 15.4 lb/in²
Explanation:
Given that,
Force applied, F = 26.4 lb
Area of cross section, A = 1.71 in²
To find,
Pressure.
Solution,
Pressure is equal to force per unit area of cross section.
[tex]P=\dfrac{F}{A}\\\\P=\dfrac{26.4\ lb}{1.71\ in^2}\\\\P=15.43\ lb/in^2\\\\P=15.43\ Pa[/tex]
Hence, the correct option is (a) "15.4 lb/in²".
In order to derive a simplified version of the Nernst equation by assuming standard temperature we can substitute which of the following into the general equation?
a. Faraday's constant
b. Standard pressure (1 atm)
c. 298 K
d. 25 °C
Answer:
c. 298 K
Explanation:
Nernst equation is an equation used in electrochemistry that relates the reduction potential of a reaction with the standard potential, temperature and concentrations of the reactants in that are been reducted and oxidized. The formula is:
E = E° - RT / nF ln [Red] / [Ox]
Where R is gas constant (8.314J/molK), T is absolute temperature (In Kelvin), n are moles of electrons and F is faraday constant (K/Volt*mol)
In electrochemistry, standard temperature is taken as 298K. That means by assuming standard temperature we can substitute T as:
c. 298 K