FINAL 05 - Computations

Question 1

If Co=500 mg/L and k=0.05 mg/L/hour, calculate t1/2. (Zero order reaction)

Answer 1

500 hours

Question 1

A drug degrades at a rate constant k=0.02 mg/L/hour, and its initial concentration is 10 mg/L. Find the half-life (Zero order reaction)

Answer 1

250 hours

Question 2

The initial drug concentration is Co=25 mg/L and the rate constant is 0.02 mg/L/hour. Determine how long it takes for the drug to degrade to 6.25 mg/L. (Zero order reaction)

Answer 2

937.5 hours

Question 3

For a drug with Co=100 mg/L and t1/2=200 hours, calculate k. (Zero order reaction)

Answer 3

0.25 mg/L/hour

Question 4

A drug with k=0.01 mg/L/hour degrades to 50 mg/L in 1,000 hours, find the initial concentration (Co) (Zero order reaction)

Answer 4

60 mg/L

Question 5

A drug has a rate constant of k=0.01 hour^-1. Find its half-life. (First order reaction)

Answer 5

69.3 hours

Question 6

For k=0.05 hour^-1, calculate the half-life. (First order reaction)

Answer 6

13.86 hours

Question 7

A drug degrades from Co=100 mg/L to C=50 mg/L in 20 hours. Find k. (First order reaction)

Answer 7

0.03477 hour^-1

Question 8

Determine the time required for a drug with Co=120 mg/L and k=0.02 hour^-1 to degrade to 30 mg/L. (First order reaction)

Answer 8

69.3 hours

Question 9

A drug has a half-life of 30 hours. Calculate k. (First order reaction)

Answer 9

0.0231 hour^-1

Question 10

For k=0.02 L/mol/hour and Co=1.0 mol/L, calculate the half-life. (Second order reaction)

Answer 10

50 hours

Question 11

If Co= 2.0 mol/L and k=0.04 L/mol/hour, find the half-life. (Second order reaction)

Answer 11

12.5 hours

Question 12

For t1/2=10 hours and Co=0.5 mol/L, find k. (Second order reaction)

Answer 12

0.2 L/mol/hour

Question 13

A liquid has a refractive index n=1.50, density d=0.8 g/mL, and molecular weight MW=120 g/mol. Find the molar refraction.

Answer 13

44.12 cm^3/mol

Question 14

Given n=1.40, d=1.2 g/mL, and MW = 180 g/mol, find the molar refraction

Answer 14

36.36 cm^3/mol

Question 15

A compound with MW=100 g/mol has a refractive index n=1.55 and density d=0.85 g/mL. Calculate the molar refraction.

Answer 15

37.46 cm^3/mol

Question 16

Determine the molar refraction of ethanol (CH3CH2OH)

Answer 16

12.96 cm^3/mol

Question 17

Calculate the molar refraction of acetic acid (CH3COOH)

Answer 17

12.86 cm^3/mol

Question 18

Find the molar refraction of benzene (C6H6)

Answer 18

21.12 cm^3/mol

Question 19

Determine the molar refraction of glucose (C6H12O6)

Answer 19

40.32 cm^3/mol

Question 20

Determine the specific rotation of a compound if the optical rotation of a 1% w/v solution in a 1 dm tube is +52.31°

Answer 20

+5231°

Question 21

Calculate the molar rotation of a compound with molecular weight MW=180 g/mol and a specific rotation of +5231°

Answer 21

+9415.8

Question 22

You need to prepare 1 L of a 0.9% NaCl isotonic solution. NaCl has a freezing point depression constant of 1.86°C and dissociated completely (i=1.8). What is the freezing point depression of the solution?

Answer 22

0.516°C

Question 23

Determine the isotonic concentration of KCl required to achieve ΔTf=0.52°C (Kf=1.86, i=1.85).

Answer 23

0.15 mol/kg

Question 24

You have a solution with a freezing point depression of 0.48°C. Is it isotonic if NaCl dissociated completely with Kf=1.86 and i=1.8?

Answer 24

No, the solution is not isotonic. (0.144 mol/kg x 58.44 = 8.41 g/L; which is slightly less than 0.9%)