Chapter 12, Problem 64A

Interpretation Introduction

Interpretation: To calculate the number of molecules of hydrogen gas.

Concept Introduction: A mole is $6.02\times {10}^{23}$ atoms/molecules. The SI unit for the amount of substance is a mole and it is represented by “mol”.

The coefficients are the numbers that are written in front of the chemical formula/symbol in order to balance a chemical reaction.

Answer to Problem 64A

The number of molecules of hydrogen gas are $1.78\times {10}^{23}\text{molecules}$ .

Explanation of Solution

The given chemical reaction is depicted as follows:

  ${\text{CH}}_{\text{4}}\left(g\right)+{\text{H}}_2\text{O}\left(g\right)\to \text{CO}\left(g\right)+3{\text{H}}_2\left(g\right)$

When methane reacts with water(steam) it yields carbon monoxide and three moles of hydrogen gas.

The amount of methane is $158\text{ g}$ .

Calculation for the molecules of hydrogen can be calculated as follows:

  $158\cancel{{\text{g CH}}_4}\times \frac{1\cancel{{\text{mol CH}}_4}}{16.0\cancel{{\text{g CH}}_4}}\times \frac{3\cancel{{\text{mol H}}_2}}{1\cancel{{\text{mol CH}}_4}}\times \frac{6.022\times {10}^{23}{\text{ H}}_2\text{molecules}}{1\cancel{{\text{mol H}}_2}}=1.78\times {10}^{23}{\text{molecules H}}_2$

Conclusion

Thus, the number of molecules of hydrogen gas are $1.78\times {10}^{23}\text{molecules}$ .