Reaction Energy & Kinetics/Equilibrium Review

1) Given the following reaction for the synthesis of water:

2H2O(g) ? 2H2(g) + O2(g) (?H = +483.6 kJ)

Write the thermochemical equation for this reaction and tell whether it is exothermic or endothermic.

2) Increasing temperature increases the rate of a reaction. What are the other 4 factors affecting reaction rate? Why does a higher temperature increase reaction rate?

3) When a 10.25 g sample of solid NH4NO3 dissolves in 87.5 g of water in a calorimeter, the temperature drops from 21.1°C to 14.7°C. Determine the quantity of heat for this solution process. (the specific heat of water is 4.184 J/g·C°)

4) Briefly explain the relationship between the temperature, transfer of heat, and heat capacity of a liquid.

5) Nitric oxide, NO, decomposes into nitrogen and oxygen gas according to this reaction:

2NO(g) ? N2(g) + O2(g) ?H = –90.3 kJ

Calculate the heat evolved per gram of nitrogen monoxide.

6) When a 4.25 g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter, the temperature drops from 22.0°C to 16.9°C. Calculate ?H (in kJ/mol of NH4NO3) for the solution process

NH4NO3(s) ? NH4+(aq) + NO3-(aq)

Assume that the specific heat of the solution is the same as that of pure water.

7) Write the equilibrium constant equation (K) for the following reaction:

CaCO3(s) ? CaO(s) + CO2(g)

8) Write the equilibrium constant equation (K) for the following reaction:

2NH3(g) <--> N2(g) + 3H2(g)

9) If the value of K is small, which of the following is true? (circle one)

  1. the [products] is greater than the [reactants]
  2. the [reactants] is greater than the [products]
  3. the [reactants] and [products] is roughly equal

10) Write the acid ionization constant (Ka) for the following reaction:

H2CO3(aq) + H2O(l) <--> H3O+(aq) + HCO3-(aq)

11) Consider the following reaction:

2NH3(g) + 92kJ/mol <--> N2(g) + 3H2(g)

(for each of the following, write either “increase” or “decrease”)

What happens to the [H2] if:
a.
you increase [N2]?
b.
you increase [NH3]?
c.
you decrease the temperature?
d.
you decrease [N2]?

(for each of the following write either “forward” or “reverse”)

Which way does the equilibrium shift (forward or reverse) if:
a.
you increase [N2]?
b.
you decrease [H2]?
c.
you increase the temperature?
d.
you increase the pressure?


12) Based on the Potential Energy Diagram provided below, answer the following questions:

  1. What is the ?H for the forward reaction (?Hforward)?
  2. What is the ?H for the reverse reaction (?Hreverse)?
  3. What is the activation energy for the reverse reaction (EA’)?
  4. What is the activation energy for the forward reaction (EA)?
  5. Is this reaction endothermic or exothermic?




Forward Reaction

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