Question

If the density of nitrogen gas at a certain pressure and temperature is 1.20 g/L, how many moles of nitrogen gas are in 15.0 L.

Answer 1

Answer:

0.643 moles

Explanation:

We are given;

Density of nitrogen gas as 1.20 g/L

Volume nitrogen as 15.0 L

We are required to calculate the number moles of nitrogen gas;

Step 1: Determine the mass of nitrogen gas

We know the density is given by dividing mass by volume.

• Density = Mass ÷ volume

Therefore, to get the mass;

• Mass = Density × volume
• Mass = 1.20 g/L × 15.0 L

        = 18 g

Step 2: Determine the mass of nitrogen gas

We know that to get the number of moles, we divide mass by molar mass;

That is, moles = Mass ÷ Molar mass

But, molar mass of nitrogen gas is 28 g/mol

Therefore;

Moles of nitrogen gas = 18 g ÷ 28 g/mol

                                     = 0.643 moles

Therefore, the number of moles of nitrogen gas 0.643 moles