Keq

Chapter 18 Review
“Reaction Rates and Equilibrium”

Name: __________________________________

  1. Energy that is available to do work is called free energy.

  2. Reaction Rate  is defined as the number of atoms, ions, or molecules that react in a given time to form products.

  3. What is the name of the minimum energy that colliding particles must have in order to react?Activation energy

  4. What is the arrangement of atoms at the peak of an energy barrier? Activated complex

  5. At equilibrium, what is the rate of production of reactants compared with the rate of production of products? The rates would be equal.

  6. What is the equilibrium constant (Keq) expression for the following reaction: C(s) + O2(g) ↔ CO2(g)

Keq=CO2/O2

  1. Which of the following is true about the combustion of carbon:  a) the reaction is spontaneous, or  b) entropy decreases?

  2. Why does a higher concentration make a reaction faster?Increase the number of collisions

  3. The amount of disorder in a system is measured by its Entropy.

  4. Entropy measures the amount of disorder

  5. What happens to a reaction at equilibrium when more reactant is added to the system? More product would be produced.

  6. Which reaction results in the greatest increase in entropy:   a) A → B, or b) A → 2B

  7. If a reaction has an equilibrium constant (Keq) just greater than 1, how do we interpret that information?Product is favored

  8. A catalyst works by Lowering of activation energy.

  9. If sulfur dioxide and oxygen can be made into sulfur trioxide, what is the reverse reaction?2SO3→2SO2 +O2,

  10. Which variable is NOT required to calculate the Gibbs free-energy change for a chemical reaction:  a) change in enthalpy, or b) temperature in oC?

  11. What is the effect of adding more water to the following equilibrium reaction: 

 CO2 + H2O ↔ H2CO3

More H2CO3 is made

  1. In an endothermic reaction at equilibrium, what is the effect of raising the temperature?

Reaction shifts toward the product-to the right

  1. What is the numerical value  (+ or -) of Gibbs free-energy change for a spontaneous reaction?

negative

  1. At what stage of a reaction do atoms have the highest energy?

Activated complex

  1. Which of the following systems has the highest entropy:                         

a) 10 mL of water at 50 oC, or          b) 10 mL of water at 100 oC? 

  1. What happens to a catalyst in a reaction?

Nothing

  1. Write the rate law for the following reaction:  A + 2B → C + D (not doing)

  2. Activation energy is the minimum energy needed for a chemical reaction that will take place.

  3. Is the melting of ice at a temperature above 0 oC:  a) endothermic, or b) exothermic?

  4. Consider the reaction:  N2(g) + 3H2(g) ↔ 2NH3(g)     What is the effect of decreasing the volume on the contained gases? Product Favored

  5. Spontaneous reactions always give off free energy.

  6. Why does a higher temperature cause a reaction to go faster? Increase the number and rate of collisions

  7. What 2 factors determine whether or not a reaction is spontaneous? High entropy and low of collisions

  8. What physical state of nitrogen has the highest entropy? Gas if you compare solid, liquid, and gas

  9. What is another name for the catalysts in your body?Enzymes

  10. Why does a catalyst cause a reaction to proceed faster? Lowers activation energy

  11. In an equilibrium reaction with a Keq of  1 x 108, the Products are favored.

  12. Which of the following explains why melting of ice is spontaneous at room temperature and pressure: a) it is accompanied by an increase in entropy, or b) it is accompanied by an increase in energy?

  13. The Keq of a reaction is 4 x 10-7.  At equilibrium, the Reactants are favored.

  14. Which change would shift the following reaction to the right:  4HCl(g) + O2(g) ↔ 2Cl2(g) + 2H2O(g)  a) decrease of pressure, or            b) increase of pressure?

  15. In which of these systems is the entropy decreasing: 

a) salt dissolving in water, or          b) a liquid cooling?

  1. Given: 2NClO(g) ↔ 2NO(g) + Cl2(g)   An analysis of the equilibrium mixture in a 1 L flask is: NClO = 1.6 M; NO = 6.4 M; Cl2 = 0.49 M.  Calculate the value of Keq.

Keq=6.42(0.49)/1.62=7.84

  1. A mixture of hydrogen and iodine are in equilibrium with hydrogen iodide, as shown in the equation:   H2 + I2 ↔ 2HI Calculate the concentration of HI when the Keq is 1 x 105, the equilibrium concentration of H2 is 0.04 M, and the equilibrium concentration of I2 is 0.009 M.

Keq= HI2/H2I2= root 1X105(0.04)(0.009)=root 36 HI=6