Chapter 6.2, Problem 6RQ

Interpretation Introduction

Interpretation: The percent of nitrogen by mass in the given compounds with the help of below graph for NaCN, HNO₃, NH₃ and Ca(NO₃)₂ needs to be matched.

Concept Introduction: Mass percentage is the way to calculate the percentage of each element in the given molecular compounds. The mathematical expression of mass percentage can be shown as:

  $\text{Mass percentage = }\frac{\text{Number of element × mass of N}}{\text{molar mass of compound}}\times 100$

Answer to Problem 6RQ

A = NaCN

B = NH₃

C = Ca(NO₃)₂

D = HNO₃

Explanation of Solution

Given information:NaCN, HNO₃, NH₃ and Ca(NO₃)₂ have N element.

Molar mass of N = 14.00 g/mol

Molar mass of NaCN = 49.00 g/mol

Molar mass of HNO₃ = 63.01 g/mol

Molar mass of NH₃ = 17.0 g/mol

Molar mass of Ca(NO₃)₂ =164 g/mol

Calculate the mass percentage of N in each compound:

  $\begin{array}{l}\text{Mass percentage of N in NaCN = }\frac{\text{1 × 14}\text{.00 g/mol}}{\text{49}\text{.00 g/mol}}\times 100=28.6\%\\ {\text{Mass percentage of N in HNO}}_{\text{3}}\text{ = }\frac{\text{1 × 14}\text{.00 g/mol}}{\text{63}\text{.01 g/mol}}\times 100=22.2\%\\ {\text{Mass percentage of N in NH}}_{\text{3}}\text{ = }\frac{\text{1 × 14}\text{.00 g/mol}}{\text{17}\text{.0 g/mol}}\times 100=82.4\%\\ {\text{Mass percentage of N in Ca(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{ = }\frac{\text{2 × 14}\text{.00 g/mol}}{\text{164 g/mol}}\times 100=17.1\%\end{array}$

Thus the compound:

A = NaCN

B = NH₃

C = Ca(NO₃)₂

D = HNO₃

Conclusion