ARC 2024 REVIEW DAY 1

Question 1

Aspirin is made by the reaction of salicylic acid with acetic anhydride with a yield of 75%. How many grams of aspirin will be produced?

Question 2

Classify each of the following as homogenous or heterogenous
I. a door
II. the air you breathe
III. a cup of coffee (black)
IV. the water you drink
V. salsa
VI. your lab partner

Answer 2

hetero, homo, homo, homo, hetero, hetero

Question 3

How many beta particles are emitted in the decomposition of 238U92 to 206Pb82?

Answer 3

6

Question 4

Give the mass of the empirical formula of the following compound if a sample contains 57.8%C, 3.6%H, and 38.6%O by mass.

Answer 4

C4H3O2

Question 5

The decomposition of iodoethane in the gas phase proceeds according to the following reactions:

C2H5I (g) —> C2H4 (g) + HI (g)

At 660K, k=7.2x10^-4 /s and at 720K, k=1.70x10^-2/s. If the initial pressure of iodoethane is 894 torr at 245 degC, what is the pressure of iodoethane after three half-lives?

Question 6

Where in the body does fatty acid synthesis occur?

Answer 6

Cytoplasm

Question 7

A solution of an unknown base was titrated with 0.150M HCl and 22.0ml of acid was needed to reach the end point of the titration. How many moles of the unknown base were in the solution?

Question 8

Suppose you have a phosphate buffer of pH 7.21. If you add more solid NaH2PO4 to this buffer, would you expect the pH of the buffer to increase, decrease, or remain unchanged?

Question 9

A solution is basic if:

a. [OH-I > 0
b. [OH-] = 1x10^-7 M
c. [OH-] > [H+]
d. [OH-] > 1xi10^-7M

Answer 9

c. [OH-] > [H+]

Question 10

Water at room temperature usually has a slightly acidic pH. This is largely attributed to what compound(s)?

a. Sulfuric acid
b. Dissolved metals
c. Carbonic acid
d. Nitric acid

Answer 10

c. Carbonic acid

Question 11

When benzoic acid dissolves in water, it partially reacts with water and ionizes to form benzoate and hydronium ions. In this reaction, what is the conjugate acid?

a. Benzoate ions
b. Hydronium ions
c. Water
d. Benzoic acid

Answer 11

b. Hydronium ions

Question 12

BHClO4 is a salt formed from the weak base B (Kb=1x10^-4) and perchloric acid, a strong acid. Find the pH of 0.1M BHClO4.

a 5.5
b 2.15
c 8.93
d 10.1

Answer 12

a 5.5

Question 13

What is the pH Of a 0.035M KOH Solution?

a. 12.54
b. 1.46
c. 3.5
d. 9.97

Answer 13

a. 12.54

Question 14

A 0.045M solution of benzoic acid has a pH of 2.78. Calculate its pKa.

a. 6.75
b. 2.15
c. 5.77
d. 4.2

Answer 14

d. 4.2

Question 15

A 0.1M solution of a base has pH=9.28. Find Kb.

a. 5.2X10^-8
b. 3.6X10^-9
c. 4.4X10^-6
d. 1.7X10^5

Answer 15

b. 3.6X10^-9

Question 16

A 0.1M solution of a base is 2% hydrolyzed. Find Kb.

a. 2.4x10^-8
b. 5.5x10^-9
c. 3.1x10^-7
d. 4.1x10^-5

Answer 16

d. 4.1x10^-5

Question 17

A 10.231g sample of window cleaner containing ammonia was diluted with 39.466g of water. Then 4.373g of solution were titrated with 14.22mL of 0.1063M HCI to reach a bromocresol green endpoint. Find the weight % of NH3 (17.031) in the cleaner.

a. 10.9%
b. 16.3%
c. 5.33%
d. 2.86%

Answer 17

d. 2.86%