Chem Exam

Exam 1. What is the catalyst? Sketch a potential energy diagram and use it to explain how addition of the catalyst affects a hypothetical chemical reaction A + B --> C + D.

2. The equilibrium constant Kp for a particular reaction 2A + B --> 4C + 7D is 0.75. Calculate Kc for this reaction.

3. The equilibrium constant for a particular reaction is 1250. Calculate the standard molar Gibbs energy change for this reaction.

4. Two chemical reactions have standard molar Gibbs energies that are -106 kJ/mol and 27 kJ/mol, respectively. Sketch a potential energy diagram to explain which of these chemical reactions will have more product than reactant at equilibrium. Which of these chemical reactions will have the largest equilibrium constant? Write the equation relating DGo and the equilibrium constant in your explanation.

5. A certain reaction happens in two steps. In the first step, A forms B and is slightly endothermic with a high activation energy barrier. In the second step, B forms C + D, which is highly exothermic with a very low activation energy barrier. Sketch the potential energy diagram for this two-step reaction.

6. Write the integrated rate laws for first-order and second-order chemical reactions. Explain how these equations can be used to analyze data from a kinetics experiment to determine if the reaction being studied is first-order or second-order.

7. A certain first-order reaction has a half-life of 137 seconds. What is the rate constant for this reaction?

8. Explain the difference between studying the kinetics of a chemical reaction and studying the equilibrium of that same chemical reaction.

9. There are three simple theories of acid-base reactions. State each of these theories in terms of how acids and bases are defined.

10. Identify the trend in the strength of the following acids in terms of periodic properties: H2O,H2S, H2Se, H2Te.

11. Sulfuric acid and bicarbonate react to produce carbonic acid and bisulfate. Write the balanced chemical equation for this acid-base reaction and state whether you expect to find a higher concentration of reactants or products at equilibrium.