**CHEMISTRY 31**

**Summer, 2016 - Dixon**

**Homework Set 1 (for Exam 1)**

**Note: Text problems will not be collected but there will
be a 10 point quiz on the homework completion date unless otherwise specified**

**Chapter** **Problems** **Date
to finish **

**Set 1.1 June
2**

Ch. 1 1a, 5, 11, 15, 20, 23, 26, 32, 35,

**Turn in corrected diagnostic quiz by Feb. 4 (10 points).
No Homework to Turn in**

Ch. 1 37, 42, 46

Ch. 3 1, 2, 5a-d, 11, 14, 16a-f

Ch. 4 4a, b, 9, 11

**Additional Problem 1.1 (3 points)**

The following method is used to capture, oxidize and titrate
sulfur dioxide (SO_{2}) in air in order to measure its concentration.
Air is bubbled into 25.0 mL of an 0.0050 M NaOH solution at a rate of 1.00 L
(air)/min for 151 min. Excess hydrogen peroxide is present which converts the
sulfur dioxide into sulfuric acid through the following reaction:

SO_{2}(g) + H_{2}O_{2}(aq)
↔ H_{2}SO_{4}(aq) + H_{2}O(l)

The sulfuric acid is neutralized by the OH^{-}. The
excess NaOH (that not reacted with H_{2}SO_{4}), then is
titrated with HCl, and required 38.1 mL of 0.00233 M HCl. Determine the
concentration of SO_{2} in the air in nmol/L.

**Additional Problem 1.2 (4 points)**

A chemist wishes to weigh out iron for a reaction but her
balance is broken. She decides that she can determine the mass of iron by
measuring the length and diameter of an iron rod. The density of iron is 7.86 __+__
0.01 g cm^{-3}, the length of the rod is 32.4 __+__ 0.4 mm and the
diameter of the rod is 4.16 __+__ 0.05 mm.

a) Calculate the **mass of iron added. **The volume of a
rod equals πˇ*d*^{2}ˇ*l*/4, where *d* is the rod
diameter and *l* is the rod length.

b) Calculate the **uncertainty in the mass of iron added**.

c) Which measurement contributed most to the overall uncertainty?

** **

**Set 1.3 June
16**

Ch. 4 20, 21, 30

Ch. 6 4, 6, 8, 15-17

**Additional Problem 1.3 (3 points)**

3. A certain 100 point quantitative analysis exam has an average value of 64.2 and a standard deviation of 19.0. If the cut-off limit for an "A" is 87, determine what percentage of students should be getting an A. Assume the distribution of test scores is Gaussian, and use the Z-Table below - find the closest Z value; do not interpolate.