Which of the following best describes the values of the rate constant, k , and t

Question

Which of the following best describes the values of the rate constant, k, and the equilibrium constant, Kc, when the temperature of an exothermic reaction is increased?

The value of rate constant increases, and the value of the equilibrium constant increases.

The value of rate constant increases, and the value of the equilibrium constant decreases.

The value of rate constant decreases, and the value of the equilibrium constant decreases.

The value of rate constant decreases, and the value of the equilibrium constant increases.

The value of the rate constant increases, but the value of the equilibrium constant does not change.

2.

What is the equilibrium constant expression for KC for the following heterogeneous reaction?

2CO(g) ? C(s) + CO2(g)

[CO]2

3.

If the following system starts out at equilibrium, which of the following will cause Q > K until equilibrium is re-established?
      A(g) + 2B(g) ? C(g) + D(s)    ?H< 0

Lowering the temperature

Adding a small amount of B(g)

Adding a small amount of C(g)

Adding a small amount of D(s)

Either adding a small amount of C(g) or adding a small amount of D(s)

4.

How will the pH change when 90.0 mL of water is added to 10.0 mL of 0.10 M HNO3?

The pH will decrease by 10.00 pH units.

The pH will decrease by 1.00 pH unit.

The pH will increase by 10.00 pH units.

The pH will increase by 1.00 pH unit.

The pH will not change.

5.

In which of the following does hydrogen bonding occur when in the pure liquid state?

CH3-O-CH3

HCl

CH3CH2SH

CH3CH2OH

All of these

6.

Which of the following decreases the solubility of a gas in solution?

Increasing gas pressure and increasing temperature

Increasing gas pressure and decreasing temperature

Decreasing gas pressure and increasing temperature

Decreasing gas pressure and decreasing temperature

Adding more water

The value of rate constant increases, and the value of the equilibrium constant increases.

The value of rate constant increases, and the value of the equilibrium constant decreases.

The value of rate constant decreases, and the value of the equilibrium constant decreases.

The value of rate constant decreases, and the value of the equilibrium constant increases.

The value of the rate constant increases, but the value of the equilibrium constant does not change.

2.

What is the equilibrium constant expression for KC for the following heterogeneous reaction?

2CO(g) ? C(s) + CO2(g)

[CO]2

3.

If the following system starts out at equilibrium, which of the following will cause Q > K until equilibrium is re-established?
      A(g) + 2B(g) ? C(g) + D(s)    ?H< 0

Lowering the temperature

Adding a small amount of B(g)

Adding a small amount of C(g)

Adding a small amount of D(s)

Either adding a small amount of C(g) or adding a small amount of D(s)

4.

How will the pH change when 90.0 mL of water is added to 10.0 mL of 0.10 M HNO3?

The pH will decrease by 10.00 pH units.

The pH will decrease by 1.00 pH unit.

The pH will increase by 10.00 pH units.

The pH will increase by 1.00 pH unit.

The pH will not change.

5.

In which of the following does hydrogen bonding occur when in the pure liquid state?

CH3-O-CH3

HCl

CH3CH2SH

CH3CH2OH

All of these

6.

Which of the following decreases the solubility of a gas in solution?

Increasing gas pressure and increasing temperature

Increasing gas pressure and decreasing temperature

Decreasing gas pressure and increasing temperature

Decreasing gas pressure and decreasing temperature

Adding more water

Explanation / Answer

Answer –

1)

When the temperature of an exothermic reaction is increased then there is change in rate constant as well as equilibrium constant.

The rate constant also increase, since the rate constant is the directly proportional to temperature.

For exothermic reaction when we increase temp means reaction gets reversed and equilibrium constant also gets inversed, so it decrease. So second option is correct - The value of rate constant increases, and the value of the equilibrium constant decreases.

2)

We are given , reaction - 2CO(g) <-----> C(s) + CO2(g)

We know in the equilibrium constant expression there is only gases and aqueous phases included, so

equilibrium constant expression, Kc = [CO2(g)] / [CO(g)]2

3)

We know adding the reactant the equilibrium shifted towards product side and when we added product then it is shifted towards reactant side.

So if we need Q>K means initial concentration ratio is more than at equilibrium, if we added more product then it is more reactant formed, so we need to adding a small amount of C(g) that cause Q >K. D(s) is not included the reaction quotient, so it is has no any effect .

4 )

We are given, 10.0 mL of 0.10 M HNO3

So pH for 10.0 mL of 0.10 M HNO3 is

[HNO3] = [H+] = 0.10

pH = -log [H+]

      = - log 0.10

      = 1.0

When we added 90 ml water then new molarity of HNO3 is

M2 = M1V1/ V2

     = 0.10 M * 10.0 mL / 90 mL

    = 0.011 M

So, [HNO3] = [H+] = 0.011

pH = -log [H+]

      = - log 0.011

      = 1.95

So it is near by 2

So pH increase from 1 to 2 , means it increase by 1 unit.

So correct option is - The pH will increase by 1.00 pH unit.

5)

We know the h-bonding occurred between the , O or N or F and H atom.

We are given ether, HCl, thiol and alcohol , so only alcohol can formed H-bonding.

So correct option is - CH3CH2OH

6)

Solubility of a gas in solution is depend on the pressure and temp, as the pressure increase solubility increase of gases, so decreases the solubility of a gas in solution means decrease in pressure and temp.

So answer is - Decreasing gas pressure and decreasing temperature

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