Chapter 6, Problem 21A

(a)

Interpretation Introduction

Interpretation: The formula of potassium phosphate and its molar mass needs to be determined.

Concept Introduction: The molar mass is the mass of a given chemical element or chemical compound in 1 mol. The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Answer to Problem 21A

Chemical formula of a compound represents atoms of elements present in a compound.

Potassium phosphate- K₃PO₄

  $Molarmassof{K}_{{}_3}P{O}_4=212.2$

Explanation of Solution

  ${\text{Molar mass of K}}_{\text{3}}{\text{PO}}_{\text{4}}\text{=Atomic mass of K+Atomic mass of P+4×Atomic mass of O}$

  $\begin{array}{l}=3\times 39.10\times 30.9+4\times 16\\ =212.\text{2 g/mol}\end{array}$

(b)

Interpretation Introduction

Interpretation: The formula of dinitrogen pentaoxide and its molar mass needs to be determined.

Concept Introduction: The molar mass is the mass of a given chemical element or chemical compound in 1 mol. The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Answer to Problem 21A

Chemical formula of a compound represents atoms of elements present in a compound.

Dinitrogen pentaoxide-N₂O₅

  $Molarmassof{N}_{{}_2}{O}_5=108.01$

Explanation of Solution

  ${\text{Molar mass of N}}_{\text{2}}{\text{O}}_{\text{5}}\text{=2×Atomic mass of N+5×Atomic mass of O}$

  $\begin{array}{l}=2\times 14.01+5\times 16\\ =108.01\text{ g/mol}\end{array}$

(c)

Interpretation Introduction

Interpretation: The formula of lead (II) nitrate and its molar mass needs to be determined.

Concept Introduction: The molar mass is the mass of a given chemical element or chemical compound in 1 mol. The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Answer to Problem 21A

Chemical formula of a compound represents atoms of elements present in a compound.

Lead (II) nitrate − Pb(NO₃)₂

  $MolarmassofPb{\left(N{O}_3\right)}_2=331.22$

Explanation of Solution

  $\text{Molar mass of Pb}{\left({\text{NO}}_{\text{3}}\right)}_{\text{2}}\text{=Atomic mass of Pb+2(Atomic mass of N+3×Atomic mass of O atom)}$

  $\begin{array}{l}=207.2+2\times (14.01+3\times 16)\\ =331.22\text{ g/mol}\end{array}$

(d)

Interpretation Introduction

Interpretation: The formula of acetic acid and its molar mass needs to be determined.

Concept Introduction: The molar mass is the mass of a given chemical element or chemical compound in 1 mol. The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Answer to Problem 21A

Chemical formula of a compound represents atoms of elements present in a compound.

Acetic acid − CH₃COOH

  $MolarmassofC{H}_{3}COOH=60.05$

Explanation of Solution

  $\begin{array}{l}{\text{Molar mass of CH}}_{\text{3}}\text{COOH=Atomic mass of C+3×Atomic mass of H+Atomic mass of C+}\\ \text{2×Atomic mass of O atom+Atomic mass of H)}\end{array}$

  $\begin{array}{l}=12.01+3\times 1.008+12.01+2\times 16+1.008\\ =60.05\text{ g/mol}\end{array}$

(e)

Interpretation Introduction

Interpretation: The formula of calcium phosphide and its molar mass needs to be determined.

Concept Introduction: The molar mass is the mass of a given chemical element or chemical compound in 1 mol. The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.

Answer to Problem 21A

Chemical formula of a compound represents atoms of elements present in a compound.

Calcium phosphide -Ca₃P₂

  $MolarmassofC{a}_3{P}_2=182.04$

Explanation of Solution

  ${\text{Molar mass of Ca}}_{\text{3}}{\text{P}}_{\text{2}}\text{=3×Atomic mass of C+2×Atomic mass of P}$

  $\begin{array}{l}=3\times 40.08+2\times 30.9\\ =182.04\text{ g/mol}\end{array}$