The gas inside a balloon is characterized by the following measurements: pressure = 725.5 mmHg; volume = 400.0 mL; temperature = 16.5 C

The number of moles of gas in the ballon is 0.01606mol

Explanation:

The question is "What is the number of moles of gas in the balloon?"

Solution

1. Data

a) p = 725.5 mmHg

b) V = 400.0mL

c) T = 16.5ºC

d) n = ?

2. Formula

Ideal gas equation:

pV = nRT

3. Solution

a) Conversion of units:

p = 725.5 mmHg * 1 atm / 760.0 mmHg = 0.954605 atm

V = 400.0mL * 1L / 1,000mL = 0.4000L

T = 16.5 + 273.15 K = 289.65K

b) Clear n from the formula:

n = (pV) / (RT)

c) Substitute and compute:

n = (0.954605atm * 0.4000L) / (0.08206atm·L/K·mol * 289.65) n = 0.01606mol