Question

Oxides of nitrogen such as nitrogen monoxide, NO, are atmospheric pollutants.

the exhaust from the car engine contains 0.00200% volume of nitrogen monoxide.

calculate the number of molecules of nitrogen monoxide in 960dm³ of exhaust gas at room temp and pressure.
one mole of any gas contains 6.02x10²³.

Answer 1

The number of molecules of nitrogen monoxide in 960 dm³ of exhaust gas at room temperature and pressure is 5.16×10²⁰ molecules

How to calculate the number of molecules of nitrogen monoxide?

First, we shall calculate the volume of the nitrogen monoxide in the exhaust. Details below:

• Percentage of nitrogen monoxide = 0.00200%
• Volume of exhaust = 960 dm³
• Volume of nitrogen monoxide = ?

Volume of nitrogen monoxide = volume of exhaust × percentage

= 960 × 0.002%

= 0.0192 dm³

Next, we shall obtain the mole of nitrogen monoxide. Details below:

• Molar volume = 22.4 dm³
• Volume of nitrogen monoxide = 0.0192 dm³
• Mole of nitrogen monoxide =?

Mole of nitrogen monoxide = Molar volume / Volume

= 0.0192 / 22.4

= 0.000857 mole

Finally, we shall obtain the number of molecules of nitrogen monoxide. This is shown below:

• Mole of nitrogen monoxide = 0.000857 mole
• Avogadro's Number = 6.02×10²³
• Number of molecules of nitrogen monoxide =?

Number of molecules = Mole × Avogadro's number

= 0.000857 × 6.02×10²³

= 5.16×10²⁰ molecules