Chapter 6, Problem 62A

Interpretation Introduction

Interpretation:

The mass of sodium hydroxide which has the same number of oxygen atoms as 100.0 g of ammonium carbonate needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 62A

The mass of sodium hydroxide is 125.03 g

Explanation of Solution

Given information:

The formula of ammonium carbonate is (NH₄)₂CO₃

Molar mass of ammonium carbonate is 96 gmol-1

Mass of ammonium carbonate is 100.0 g

Calculation:

The calculation of moles is shown below:

  $\begin{array}{c}\text{moles}\text{of}{\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{CO}}_{\text{3}}\text{=}\frac{\text{mass}\text{of}{\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{CO}}_{\text{3}}}{\text{molar}\text{mass}\text{of}{\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{CO}}_{\text{3}}}\\ \text{=}\frac{\text{100}\text{.0}\text{g}}{\text{96}{\text{gmol}}^{\text{-1}}}\\ \text{=}\text{1}\text{.042}\text{mol}\end{array}$

The calculation of number of atoms of oxygen is shown below:

Number of atoms of oxygen = 3×1.042

= 3.126 moles of atoms of oxygen

Moles of NaOH = 3.126 moles

The calculation of mass of NaOH is shown below:

Mass of NaOH = moles ×molar mass

= 3.126 mol × 39.997 gmol-1

= 125.03 g

Conclusion

The mass of sodium hydroxide is 125.03 g