Question

The catalytic decomposition of hydrogen peroxide yields oxygen gas and water. In an experiment, decomposition of hydrogen peroxide yielded 75.3 mL of gas collected over water at 25°C and 742 torr. What mass of oxygen gas was collected?

Answer 1

Answer:

The mass of oxygen collected is 0.0928 grams

Explanation:

Step 1: Data given

Yield of oxygen gas = 75.3 mL

Temperature = 25°C

Pressure = 742 torr = 0.976 atm

vapor pressure of water at 25 °C = 23.7695 torr = 0.0313 atm

Molecular weight of O2 = 32 g/mol

universal gas constant = 0.08206 L* atm / K* mol

Step 2: Calculate the vapor pressure (= pO2)

Ptotal + pO2 + pH2O

pO2 = ptotal -pH2O

pO2 = 0.976 atm - 0.0313 atm =  0.9447 atm

Step 3: Calculate moles O2:

p*V = n*R*T

⇒ p = the pressure of O2 = 0.9447 atm

⇒ V = the volume = 0.0753 L

⇒ n = the number of moles = TO BE DETERMINED

⇒ R= the gas constant = 0.08206 L*atm/K*mol ( 24 torr)

⇒ T = the temperature = 25°C = 298.15 Kelvin

n = (p*V)/(R*T)

n = (0.9447 atm * 0.0753 L) /(0.08206 l*atm/K*mol * 298.15 K)

number of moles = 0.0029 moles O2

Step 4: Calculate mass of O2

Mass O2 = moles O2 * Molar mass O2

Mass O2 = 0.0029 * 32 g/mol

Mass O2 =0.0928 grams

The mass of oxygen collected is 0.0928 grams