The following reaction is second order in [A] and the rate constant is 0.025 M-1s-1: The concentration of A was 0.65 M at 33 s. The initial concentration of A was ________ M.

Select one:

a. 0.24

b. 1.2 � 10-2

c. 0.27

d. 2.4

e. 1.4

Answer:

The standard cell potential for this galvanic cell is 0.27 V.

Explanation:

The standard redox potentials, E° of the Pb and Cd are:

Pb²⁺(aq) + 2e⁻ → Pb   E° = -0.13 V

Cd²⁺(aq) + 2e⁻ → Cd   E° = -0.40 V    

The standard cell potential for this galvanic cell can be calculated as follows:

[tex] E_{cell}^{0} = E^{0}_{c} - E^{0}_{a} [/tex]     (1)

Where:

c: is for cathode    

a: is for anode  

As we can see in the standard redox potentials of Pb and Cd, the Pb is going to be reduced (cathode) and the Cd is going to be oxidated (anode).

By replacing the standard redox potentials of Pb and Cd into equation (1) we have:

[tex] E_{cell}^{0} = E^{0}_{c} - E^{0}_{a} = -0.13 V - (-0.40 V) = 0.27 V [/tex]

Therefore, the standard cell potential for this galvanic cell is 0.27 V.

I hope it helps you!                

Answer:

Exothermic

Explanation:

A reaction is said to be exothermic when heat is evolved in the process. The evolution of heat implies that the energy of reactants is greater than that of the products, hence energy is given off when the products are formed.

If you dissolve sodium hydroxide in water, the vessel feels hot when touched. This signifies that energy is given off during the process. Hence the formation of an aqueous solution of sodium hydroxide is exothermic.

Answer:

[tex]\rho =1g/mL[/tex]

Explanation:

Hello,

In this case, since the density is defined as the ratio between the mass and the volume as shown below:

[tex]\rho =\frac{m}{V}[/tex]

We can compute the density of water for the given 43 g that occupy the volume of 43 mL:

[tex]\rho =\frac{43g}{43mL}=1g/mL[/tex]

Regards.

Answer:

[tex]Q=1.04kJ[/tex]

Explanation:

Hello,

In this case, for latent heat (phase change) we need to consider the enthalpy associated with the involved process, here, melting or fusion; thus, the enthalpy of fusion of copper is 13.2 kJ/mol, therefore, the heat is computed as:

[tex]Q=m\Delta H_{fus}[/tex]

Nevertheless, since the given enthalpy is per mole of copper, we need to use its atomic mass to perform the correct calculation as follows:

[tex]Q=5.0g*\frac{1mol}{63.54}* 13.2\frac{kJ}{mol}\\ \\Q=1.04kJ[/tex]

Which is positive as it needs to be supplied to the system.

Best regards.

Answer:

B. Ni

D. Sn

Explanation:

Electrode Potential is the potential difference set up between an element and a solution of its ion. It is a measure of the tendency of an element to form ions.

The electrode potentials vary from one metal ion or metal system to another and the value depends on:

concentration of ions in the solution

the temperature at which the measurement is made , and

the overall energy change.

When two half-cells are joined together through a salt bridge, the e.m.f (electromotive force) of the cell formed is the algebraic difference between the two electrode potentials.

However, the set up in which chemical energy is converted to electrical energy is known as an Electrochemical cell. It consists of two half cells ;

an oxidation half-cell reaction  

a reduction  half cell reaction.

From the information given:

the standard reduction potential for each metal under standard conditions in the electrochemical series is as follows :

[tex]E^0 _{Pb} = -0.126 \ V[/tex]

[tex]E^0 _{Cr} = - 0.74 \ V[/tex]

[tex]E^0 _{Ni} =- 0.23 \ V[/tex]

[tex]E^0 _{Zn} =- 0.76 \ V[/tex]

[tex]E^0 _{Sn} = -0.13 \ V[/tex]

[tex]E^0 _{Cd} = - 0.40 \ V[/tex]

We will realize that  Ni and Sn have reduction values in between Pb and Cd.

Thus , Ni can be oxidized by Pb2+  solution  but not with a Cd2+ solution

The metal(s) that can be oxidized with a [tex]Pb^{2+}[/tex] solution

B. Ni

D. Sn

It is the potential contrast set up between a component and an answer of its particle. It is a proportion of the inclination of a component to shape particles. The cathode possibilities shift from one metal particle or metal framework to another and the worth relies upon:

Centralization of particles in the arrangement, the temperature at which the estimation is made , and the general energy change.

Whenever two half-cells are combined through a salt scaffold, the e.m.f (electromotive power) of the cell shaped is the mathematical contrast between the two terminal possibilities.

However, the set up in which chemical energy is converted to electrical energy is known as an Electrochemical cell. It consists of two half cells ;

an oxidation half-cell reaction  and a reduction  half cell reaction.

On seeing the values of electrode potential from electrochemical series we observe that  Ni and Sn have reduction values in between Pb and Cd.

Thus , Ni and Sn can be oxidized by  [tex]Pb^{2+}[/tex] solution but not with a [tex]Cd^{2+}[/tex]solution.

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Answer:

pKa bromocresol green is ≅4.5

Explanation:

The bromocresol green is a chemical indicator used in titrations with equivalence point at pH's between 3 and 5.

Is an indicator that, in acidic region is yellow, and in basicic region is blue. The intermediate color is green (at pH≅ 4.5).

As at the intermediate color of the indicator pKa = pH,

Answer:

Option a: positron emission.

Explanation:

In the transformation we have:

⁶⁷Ga  →  ⁶⁷Zn  

The reaction is:

[tex]^{67}_{Z}X \rightarrow ^{67}_{Z -1}Y[/tex]

For Ga to become Zn, the atom nucleus has to lose a proton, so in the given options, the reaction that involves the transformation of a proton is the option a, positron emission.

In a positron emission, a proton becomes into a neutron and a positron:

[tex]^{A}_{Z}X \rightarrow ^{A}_{Z-1}Y + ^{0}_{+1}e[/tex]

Therefore, the correct answer is option a: positron emission.

I hope it helps you!

Answer:

The correct answer is  1.977 % m/v ≅ 2% m/v

Explanation:

We have:

0.617 M = 0.617 moles methanol/ 1 L solution

We need:

%m/v= grams of methanol/100 mL solution

So, first we convert the moles of methanol to grams by using the MM (32.04 g/mol). Then, we multiply by 0,1 to convert the volume in liters to 100 mL by using the ratio: 100 mL= 0.1 L:

0.617 mol / 1 L x 32.04 g/mol 0.1 L/100 mL= 1.977 g/100 mL= %m/v

The concentration in [tex]\%_{m/v}[/tex] of a 0.617 M aqueous solution of methanol is 1.98%.

To find the [tex]%_{m/v}[/tex] concentration of methanol we need to use the following equation:

[tex] \%_{m/v} = \frac{m_{s}}{V_{sol}} \times 100 [/tex]   (1)

Where:

[tex] m_{s}[/tex]: is the mass of methanol in grams

[tex] V_{sol} [/tex]: is the volume of the solution in milliliters

The molar concentration of methanol is:

[tex] C = 0.617 M = 0.617 \:\frac{mol}{L} [/tex]

From this concentration, we can find the mass of methanol

[tex] m = n*MM [/tex]   (2)

Where:

n: is the number of moles = C*V

MM: is the molar mass = 32.04 g/mol

Then, the mass of methanol is (eq 2):

[tex] m = n*MM = C*V*MM = 0.617 mol/L*1 L*32.04 g/mol = 19.77 g [/tex]

Knowing that 1 L = 1000 mL, the [tex]%_{m/v}[/tex] concentration is (eq 1):

[tex] \%_{m/v} = \frac{m_{s}}{V_{sol}} \times 100 = \frac{19.77 g}{1000 mL} \times 100 = 1.98 \% [/tex]

Therefore, the concentration in [tex]\%_{m/v}[/tex] is 1.98%.

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I hope it helps you!                

Answer:

Chlorine

Explanation:

Hello.

In this case, for the given elements, we are able to know that oxygen has 6 valence electrons, chlorine 7, nitrogen 5 and neon 8, therefore neon is not able to react as it already has 8 valence electrons. Besides, the element having the most valence electrons is chlorine and its reaction with hydrogen forms hydrogen chloride as shown below:

[tex]H_2(g)+Cl_2(g)\rightarrow 2HCl(g)[/tex]

Therefore, the required element is chlorine.

Regards.

Chlorine element would have the most valence electrons and also be able to react with hydrogen

The atomic number of hydrogen is 1 and its electronic configuration is [tex]1s^{1}[/tex] .

The atomic number of oxygen is 8 and its electronic configuration is [tex]1s^{2} 2s^{2} 2p^{4}[/tex]. The valence electron in oxgen is 6.

The atomic number of chlorine is 17 and its electronic configuration is [tex]1s^{2} 2s^{2} 2p^{6}3s^{2} 3p^{5}[/tex]. The valence electron in chlorine is 7.

The atomic number of neon is 10 and its electronic configuration is [tex]1s^{2} 2s^{2} 2p^{6}[/tex]. The valence electron in neon is 8.

The atomic number of nitrogen is 7 and its electronic configuration is [tex]1s^{2} 2s^{2} 2p^{3}[/tex]. The valence electron in nitrogen is 5.

Except Neon, all three atoms will react with hydrogen as the configuration of neon is a stable electronic configuration.

Chlorine has the greatest number of valence electrons after neon that is 7. So, chlorine would have the most valence electrons and also be able to react with hydrogen as follows:-

[tex]H_2+Cl_2\rightarrow2HCl[/tex]

Hence, the correct answer is chlorine.

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Answer:

The reaction is exothermic

Explanation:

If we look at this reaction system closely, we will discover that the energy of reactants is greater than that of the product. The excess energy possessed by the reactants must be given off at the end of the reaction.

Since ∆Hrxn = ∆Hproducts - ∆Hreactants and ∆Hreactants > ∆Hproducts hence ∆Hrxn is negative and the reaction is exothermic, hence the answer.

Answer:

E) C₂H₄(g) + H₂(g) ⇒ C₂H₆(g)

Explanation:

Which ONE of the following is an oxidation–reduction reaction?

A) PbCO₃(s) + 2 HNO₃(aq) ⇒ Pb(NO₃)₂(aq) + CO₂(g) + H₂O(l). NO. All the elements keep the same oxidation numbers.

B) Na₂O(s) + H₂O(l) ⇒ 2 NaOH(aq). NO. All the elements keep the same oxidation numbers.

C) SO₃(g) + H₂O(l) ⇒ H₂SO₄(aq). NO. All the elements keep the same oxidation numbers.

D) CO₂(g) + H₂O(l) ⇒ H₂CO₃(aq). NO. All the elements keep the same oxidation numbers.

E) C₂H₄(g) + H₂(g) ⇒ C₂H₆(g). YES. C is reduced and H is oxidized.

Answer:

a. H⁺(aq)+ OH⁻(aq) →  H₂O(l)

Explanation:

First, we will write the molecular equation for the reaction between H₂SO₄ and KOH.

H₂SO₄(aq) + 2 KOH(aq) →  K₂SO₄(aq) + 2 H₂O(l)

The complete ionic equation includes all the ions and the molecular species.

2 H⁺(aq) + SO₄²⁻(aq) + 2 K⁺(aq) + 2 OH⁻(aq) →  2 K⁺(aq) + SO₄²⁻(aq) + 2 H₂O(l)

The net ionic equation includes only the ions that participate in the reaction and the molecular species.

H⁺(aq)+ OH⁻(aq) →  H₂O(l)

Answer:

0.0338 moles of sodium bicarbonate are required to react with 0.9 mL 100% sulphuric acid solution

Explanation:

Equation of the reaction:

Na₂CO₃(aq) + H₂SO₄(aq) ---> Na₂SO₄(aq) + H₂O(l) + CO₂(g)

Since the concentration of the sulphuric acid is not given in the question, the assumption is made that the sulphuric acid solution is 100% sulphuric acid solution.

The density of 100% concentrated sulfuric acid is 1.839 g/mL.

Amount of acid in 0.9 mL solution = 0.9 mL * 1.839 g/mL = 1.655 g

Number of moles of acid in 1.655 g = mass/molar mass

Molar mass of  H₂SO₄ = 98 g/mol

Number of moles of acid in 1.471 g = 1.655 g / 98 g/mol = 0.0169 moles

From the equation of reaction,  1 mole of H₂SO₄  reacts with 2 moles of Na₂CO₃

0.0169 moles of H₂SO₄  will react with 0.0169 * 2 moles of Na₂CO₃ = 0.0338 moles

Therefore, 0.0338 moles of sodium bicarbonate are required to react with 0.9 mL 100% sulphuric acid solution

Answer:

This question is incomplete but the completed question is below

a) Identify the chemical equation that represents what would occur if naphthalene (C₁₀H₈) is burned in the presence of O₂

b) Identify how many moles of carbon dioxide would be released from the equation in (a) if 25.0 g of naphthalene were burned in the presence of excess oxygen.

c) Explain what would happen if only 1 mole of oxygen gas were available to interact with naphthalene in this reaction.

The answers to the questions are below

Explanation:

a) The chemical reaction here will be a combustion reaction. A combustion reaction involves the burning of a substance (in this case an organic compound) in excess oxygen to produce carbon dioxide and water.

The balanced equation below shows what will happen when naphthalene (C₁₀H₈) is burned in the presence of O₂

C₁₀H₈ + 10O₂  ⇒  10CO₂ + 4H₂O

b) The mass of naphthalene (C₁₀H₈) from the equation above is

when C= 12 and H = 1; C₁₀H₈ = (10 × 12) + (1 × 8) = 128 g

Mass of C₁₀H₈ from the equation in (a) above is 128 g

If 128g of C₁₀H₈ ⇒ 10 moles of CO₂

25g of C₁₀H₈ ⇒ X moles of CO₂

where X is the unknown

X = 25 × 10/128

X = 1.95 moles of CO₂

1.95 moles of CO₂ would be released from the equation in (a) if 25.0 g of naphthalene were burned in the presence of excess oxygen

(c) If just 1 mole of oxygen gas was available for the reaction in (a) above, the reaction would have been an incomplete combustion. An incomplete combustion is the process in which a substance burns in insufficient oxygen to produce carbon monoxide (CO) and water.

Answer:

Carbons 1 and 3

Explanation:

We must remember that by definition alpha carbons are the carbon (or carbons) next to the carbon that contains the main group. In this case, the main group is the carbonyl group (C = O) in the middle of the molecule. In the acetone molecule, we have three carbons, the carbons neighboring the carbon of the carbonyl group (carbon two) will be the alpha carbons. (Red and blue carbons or carbons one and three)

See figure 1 for further explanations.

I hope it helps!

Answer:

[tex](C_2H_5)_3N~+~H_2O~->~(C_2H_5)_3NH^+~+~OH^-[/tex]

Explanation:

For this question, we have to remember that definition of acid and base in the Bronsted-Lowry theory:

Acid

A substance with the ability to produce a hydronium ion ([tex]H^+[/tex]).

[tex]HA~->~H^+~+~A^-[/tex]

Base

A substance with the ability to accepts a hydronium ion ([tex]H^+[/tex]).

[tex]B~+~H^+->BH^+[/tex]

If we check the reaction mechanism (figure 1). We can see that the lone pair of electrons in the "N" atom will remove an "H" from the water molecule producing a positive charge in the nitrogen and a hydroxyl group ([tex]OH^-[/tex]).

With all this in mind, the net ionic equation would be:

[tex](C_2H_5)_3N~+~H_2O~->~(C_2H_5)_3NH^+~+~OH^-[/tex]

I hope it helps!

Answer:

[tex]\%m/m=0.15\%[/tex]

Explanation:

Hello,

In this case, we are asked to compute the by mass percent representing the toxicity of ethylene glycol in the body mass. In such a way, since the by mass percent is computed as follows:

[tex]\%m/m=\frac{m_{solute}}{m_{solute}+m_{solvent}} *100\%[/tex]

Whereas the solute is the ethylene glycol in the body mass, we obtain:

[tex]\%m/m=\frac{1.5g}{1.5g+1000g} *100\%\\\\\%m/m=0.15\%[/tex]

Best regards.

The percentage of ethylene glycol that is fatal would be 0.15%.

The toxic quantity is 1.5 g of ethylene glycol for 1000 g of body mass.

The percentage toxic quantity in relation to the body mass can be calculated as:

Percentage = mass of toxic quantity/body mass x 100%

                    = 1.5/1000 x 100%

                       = 0.15 %

Thus, the fatal level of ethylene glycol is 0.15% of body mass.

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Answer:

B. cocamide DEA

C. folic acid

D. iron

G. lauryl glucoside

Answer:

e. Lead

Explanation:

Hello,

In this case, since the equation to compute the heat in a heating or a cooling process is:

[tex]Q=mCp(T_2-T_1)[/tex]

We can see that the lower the specific heat of the substance, the higher the reached temperature as they are in an inversely proportional relationship. In such a way, we can say that e. Lead will reach the higher temperature if the same heat is added to same mass of the other metals.

Regards.

Answer:

a) The solubility of the ionic compound is reduced.

Explanation:

Let AB be the ionic compound . It will ionise as follows in solution .

         AB    ⇄    A⁺  +  B⁻

In solution AB , A⁺ and B⁻ maintain a state of equilibrium . Now if we add A⁺ ion as common ion to the solution , the equilibrium will be shifted to the left ie less of AB will ionise to maintain equilibrium . Hence the solubility of AB will be reduced .

The solubility of an ionic compound reduces when any common ion is being added to any solution.

Solubility:

Ionic compound :

When some common ion adds into a solution, the solubility of a slightly soluble ionic compound gets reduced due to :

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Answer:

Explanation:

Soak your wooden skewers in water for at least 30 minutes before using them to cook with. That way the skewers are water logged and won't catch on fire while you're cooking your soon-to-be delicious kebabs. Remember, only you can prevent kebab fires.

Answer:

Acetone.

Explanation:

Hello,

In this case, we can distinguish between polar solvent and nonpolar solvent by the nature of the bonds present in the compound. Thus, since the bonds C-Cl, C-C, C-H and C-O are nonpolar, which are contained in the toluene, carbon tetrachloride, diethyl ether and hexane, they are discarded as polar.

Nevertheless, since the carbonyl group contained in the acetone is a polar because of the formed positive and negative charges, it is actually the polar solvent, acting as an exception. This is substantiated by the fact the acetone is soluble in water whereas the other substances not,

Regards.

Answer:

b. Q

Explanation:

Equilibrium constant K is a measure of the ratio of the equilibrium concentration of the products of a reaction to the equilibrium concentration of the reactants with each concentration raised to the power corresponding to the coefficient in the balanced equation of the reaction.

On the other hand , the [tex]E^\theta_{cell}[/tex] is the standard electrode potential of the right-hand electrode minus the standard electrode potential of the left hand electrode, Thus, [tex]E^\theta_{cell}[/tex] will be zero if concentration cell in the two electrodes appears to be the same.

The Nernst equation correlates  the cell E.M.F to a standard value E and the activities of the species that takes places in the cell reaction. Thus in a concentration cell, the reaction is driven by Q

Answer:

142.36 kg

Explanation:

volume of water in the lake = surface area x depth

= 18.5 x ( 1760 x 3 )² x 39 ft³

= 2.011 x 10¹⁰ ft³

= 2.011 x 10¹⁰ x 28.3168 liter .

= 56.945 x 10¹⁰ liter .

concentration of mercury = .25 x 10⁻⁶ g / liter

= 25 x 10⁻⁸ g / liter

= 25 x 10⁻¹¹ kg / liter

mass of mercury in the water of lake

= 25 x 10⁻¹¹ x 56.945 x 10¹⁰ kg

= 142.36 kg .

Answer:

H2C=CH-CH2OH

Explanation:

Aldehydes are reduced to primary alcohols.

The first step in the reaction sequence is that the nucleophilic Hydrogen atom in the hydride reagent attacks the electrophilic Carbon in the polar carbonyl group of the aldehyde, there will now be a shift of electrons from the carbonyl to the Oxygen atom creating an intermediate metal alkoxide complex.

The reaction sequence is completed by a simple addition of a proton to the alkoxide oxygen which creates the primary alcohol product from the intermediate complex.

Answer:

See the answer below

Explanation:

The pH scale is important in science because it gives an indication of how acidic or basic a solution is. The scale ranges from 0 - 14 with 0 being the most acidic and 14 being the most basic while a pH of 7 is a neutral pH.

The pH scale is widely applicable in several scientific applications such as in medicine/health, agricultural processes, industrial processes, environmental monitoring, research and development, etc.

In medicine, the pH of the stomach is monitored in order to make some diagnosis. The normal pH of the human stomach ranges from 1.5 - 3.5 and a major deviation from this range can give an indication of wrong health.

In agriculture, the pH condition of the soil on which crops are grown is quite important. While some crops require slightly acidic soil, some will only do well in alkaline soil. Hence, the pH condition of the soil must be monitored to ensure the optimal yield of crops.

Several industrial processes require the monitoring of pH in order to ensure product's quality or monitor some important reactions. In food industries, for example, monitoring the pH of reactions is necessary in order to prevent contamination by pathogens or ensure a good organoleptic quality of the final product. It is also necessary to monitor the pH of industrial wastewaters in order to avoid polluting the environment.

Monitoring pH is also important for environmental monitoring, The pH of various water bodies or soil can give an indication of the level of pollution in the water or the soil.

The pH can be defined as the concentration of the hydrogen ions in the sample. The determination of pH helps in the designing of the study and investigating the reactions.

Some of the examples for the scientific application of pH has been:

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Answer; If a chemical has a pH of 3, how could you change its pH value to be more basic? Adding water to a chemical will dilute the acid, thus lowering the pH value to more basic.

If a chemical has a pH of 3, that means it is strong acid.To alter its pH value to be more basic, we have add strong base in excess.

First, neutralization reaction occur. After adding excess strong base, the solution becomes basic and pH become more basic.

The reaction between strong acid and base to form salt and water is called neutralization reaction.

Example: HCl + NaOH → NaCl + H2O

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Answer:

4 g/mL

Explanation:

The density of a object can be found using the following formula.

[tex]d=\frac{m}{v}[/tex]

where m is the mass and v is the volume.

We know that the mass of the object is 24.0 grams and the volume is 6.0 milliliters.  

[tex]m= 24 g\\v=6 mL[/tex]

Substitute the values into the formula.

[tex]d= \frac{24g}{6mL}[/tex]

Divide 24 g by 6 mL.

[tex]d= 4 g/mL[/tex]

The density of the object is 4 grams per milliliter.

Answer:

4 g/mL

Explanation:

density = mass/volume

therefore, density = 24/6

ρ = 4 g/mL

Answer:

number of electrons, n

Gibbs free energy change, ΔG

temperature, T

coefficients from balanced redox equation (various)

Explanation:

The standard electrode potential of a cell can be obtained from;

∆G°= -nFE°cell

Also;

E°cell= RTlnK/nF

Where;

∆G°= standard free energy of the cell

n= number of electrons transferred

F= Faraday constant

E°cell= standard cell potential

R= universal gas constant

T= temperature

K= equilibrium constant