Calculate number of molecules in given moles of a substance

Chief Editor

Oct 16, 2022

Methane (CH₄) is the major component of natural gas. How many molecules are present in 0.5 moles of a pure sample of methane?
At high temperature hydrogen sulphites (H₂S) gas given off by a volcano is oxidized by air to sulphur dioxide (SO₂). Sulphur dioxide reacts with water to form acid rain. How many molecules are there in 0.25 moles of SO₂?

Difficulty: Medium

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Problem solving strategy:

Remember that CH₄ is a molecular compound, thus 1 mole of methane will have 6.022 x 10²³ molecules. Similarly, SO₂, is a molecular compound its one mole will also have 6.022 x 10²³ molecules.

Solution:

(a) 1 mole of CH₄ contains = 6.022 x 10²³ molecules

So, 0.5 moles of CH₄ will contain = 6.022 x 10²³x 0.5 = 3.011 x 10²³ molecules

(b) 1 mole of SO₂ contains = 6.022 x 10²³molecules

So, 0.25 moles of SO₂ will contain = 6.022 x 10²³ x0.25 = 1.5055 x 10²³ molecules

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Chief Editor

Calculate number of molecules in given moles of a substance

Methane (CH4) is the major component of natural gas. How many molecules are present in 0.5 moles of a pure sample of methane?

At high temperature hydrogen sulphites (H2S) gas given off by a volcano is oxidized by air to sulphur dioxide (SO2). Sulphur dioxide reacts with water to form acid rain. How many molecules are there in 0.25 moles of SO2?

Methane (CH₄) is the major component of natural gas. How many molecules are present in 0.5 moles of a pure sample of methane?

At high temperature hydrogen sulphites (H₂S) gas given off by a volcano is oxidized by air to sulphur dioxide (SO₂). Sulphur dioxide reacts with water to form acid rain. How many molecules are there in 0.25 moles of SO₂?