Assignment

1. Solutions of hydrogen in palladium may be formed by exposing Pd metal to H₂ gas. The concentration of hydrogen in the palladium depends on the pressure of H₂ gas applied, but in a more complex fashion than can be described by Henry's law. Under certain conditions, 0.94 g of hydrogen gas is dissolved in 215 g of palladium metal.

(a) Determine the molarity of this solution (solution density = 1.8 g/cm³).

(b) Determine the molality of this solution (solution density = 1.8 g/cm³).

(c) Determine the percent by mass of hydrogen atoms in this solution (solution density = 1.8 g/cm³).

2.Compare the processes that occur when methanol (CH₃OH), hydrogen chloride (HCl), and sodium hydroxide (NaOH) dissolve in water. Write equations and prepare sketches showing the form in which each of these compounds is present in its respective solution.

3. The Henry's law constant for O₂ is 1.3 × 10^-3 M/atm at 25 ^oC. What mass of oxygen would be dissolved in a 40-L aquarium at 25 ^oC, assuming an atmospheric pressure of 1.00 atm, and that the partial pressure of O₂ is 0.21 atm?

4.What are the mole fractions of H₃PO₄ and water in a solution of 14.5 g of H₃PO₄ in 125 g of water? (a) Outline the steps necessary to answer the question. (b) Answer the question.

5. The concentration of glucose, C₆H₁₂O₆, in normal spinal fluid is 75 mg. What is the molality of the solution

6. A study of the rate of dimerization of C₄H₆ gave the data shown in the table: 2C₄H₆ → C₈H₁₂
Time (s)          0                      1600          3200              4800            6200
[C₄H₆] (M)   1.00 × 10^-2   5.04 × 10^-3   3.37 × 10^-3   2.53 × 10^-3   2.08 × 10^-3

(a) Determine the average rate of dimerization between 0 s and 1600 s, and between 1600 s and 3200 s.

(b) Estimate the instantaneous rate of dimerization at 3200 s from a graph of time versus [C₄H₆]. What are the units of this rate?
(c) Determine the average rate of formation of C₈H₁₂ at 1600 s and the instantaneous rate of formation at 3200 s from the rates found in parts (a) and (b)

7. Consider the following reaction in aqueous solution: 5Br-(aq) + BrO₃ -(aq) + 6H+(aq) → 3Br₂(aq) + 3H₂ O(l) If the rate of disappearance of Br-(aq) at a particular moment during the reaction is 3.5 × 10-4 M s-1, what is the rate of appearance of Br₂(aq) at that moment?

8. Tripling the concentration of a reactant increases the rate of a reaction nine times. With this knowledge, answer the following questions:

(a) What is the order of the reaction with respect to that reactant? (b) Increasing the concentration of a reactant by a factor of four increases the rate of a reaction four times. What is the order of the reaction with respect to that reactant?

9. Under certain conditions the decomposition of ammonia on a metal surface gives the following data:

NH3 (M)              1x10^-3       2x10^-3     3x10^-3
Rate (Mol/L/h)   1.5x10^-6   1.5x10^-6   1.5x10^-6

Determine the rate equation, the rate constant, and the overall order for this reaction.

10. What is the half-life for the first-order decay of carbon-14?6 C → 7 144 N + e-

The rate constant for the decay is 2.21× 10-4 year-1