Chapter 16, Problem 35CI

Interpretation Introduction

(a)

Interpretation:

When magnesium of mass 0.121 g is dissolved in 50.0 mL of 1.00 M HCl, some amount of ${\text{MgCl}}_{\text{2}}$ is formed along with the release of hydrogen gas. The limiting reactant in the reaction needs to be determined.

Concept Introduction:

Limiting reagent is the reactant that limits the amount of product produced in a chemical reaction.

Interpretation Introduction

(b)

Interpretation:

The volume of HCl in mL needs to be calculated at given temperature and pressure.

Concept Introduction:

From the ideal gas law, the ideal gas equation is as follows:

  $\begin{array}{l}\text{PV = nRT}\\ \text{V = }\frac{\text{nRT}}{\text{P}}\end{array}$

Here, n is number of moles, R is Universal gas constant, T is temperature and P is pressure of the gas.

Interpretation Introduction

(c)

Interpretation:

The joules of energy released by the magnesium needs to be determined.

Concept Introduction:

Heat produced can be calculated as follows:

  $Q=ms\Delta t$

Where m is the mass, s is the specific heat capacity, delta T is the change in temperature.

The mass of the substance is related to number of moles and molar mass as follows:

  $n=\frac{m}{M}$

Interpretation Introduction

(d)

Interpretation:

The heat of reaction for magnesium needs to be calculated in joules/gram and in kilojoules/mol.

Concept Introduction:

Heat released in J/g = $\frac{\text{heat}\text{in}\text{J}}{\text{mass in g }}$

Heat released in kJ/mol = $\frac{\text{heat}\text{in}\text{kJ}}{\text{mole}}$

1kJ = 1000J

  $\text{Moles = }\frac{\text{mass}}{\text{molar mass}}$