Nitrate salts (NO3-), when heated, can produce nitrites (NO2-) plus oxygen (O2). A sample of potassium nitrate is heated, and the O2 gas produced is collected in a 730 mL flask. The pressure of the gas in the flask is 2.5 atm, and the temperature is recorded to be 329 K. The value of R= 0.0821 atm L/(mol K)

How many moles of O2 gas were produced?

0.0676 moles of oxygen gas is produced

Explanation:

Step 1: Data given

Volume of the flask = 730 mL = 0.730 L

The pressure of the gas in the flask is 2.5 atm

The temperature is recorded to be 329 K

Step 2: The balanced equation

2NO3- → 2NO2- + O2

Step 3: Calculate moles oxygen gas (O2)

p*V =n * R*T

⇒with p = the pressure of oxygen gas = 2.5 atm

⇒with V = the volume of the flask = 0.730 L

⇒with n = the number of moles O2 gas

⇒with R = the gas constant = 0.0821 L*atm/mol*K

⇒with T ⇒ the temperature = 329 K

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

n = (2.5 * 0.730 ) / (0.0821*329)

n = 0.0676 moles

0.0676 moles of oxygen gas is produced

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