Chapter 4, Problem 1MCP

(a)

Interpretation Introduction

Interpretation:

Whether the given reaction, ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$ is a decomposition (D), combination (C), single-replacement (SR) or double-replacement (DR) reaction has to classified.

Concept Introduction:

Combination reaction (C) is a reaction in which two or more elements or compounds join together producing a product of different composition.  The general form of a combination reaction is $\text{A + B }\stackrel{}{\to }\text{ AB}$.

Decomposition reaction (D) is a reaction in which a single reactant undergoes decomposition and gives two or more products.  The general form of a decomposition reaction is $\text{AB }\stackrel{}{\to }\text{ A + B}$.

Single-replacement reaction (SR) is a reaction in which one atom replaces another in the compound and produces a new compound.  The general form of a single-replacement reaction is $\text{A + BC }\stackrel{}{\to }\text{ AC + B}$.

Double-replacement reaction (DR) is a reaction in which two compounds undergoes “change of partners”.  That is, two compounds react by exchanging atoms to produce two new compounds.  The general form of a double-replacement reaction is $\text{AB + CD }\stackrel{}{\to }\text{ AD + CB}$.

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

In the above reaction, both the reactants exchange their partners with each other.  ${\text{CH}}_{\text{3}}\text{COOH}$ gives ${\text{H}}^{+}$ and accepts ${\text{Ba}}^{2+}$ from ${\text{Ba(OH)}}_{\text{2}}$.  Similarly, ${\text{Ba(OH)}}_{\text{2}}$ gives ${\text{OH}}^{-}$ and accepts ${\text{H}}^{+}$ from ${\text{CH}}_{\text{3}}\text{COOH}$.

Hence, this reaction is a Double-replacement reaction (DR).

(b)

Interpretation Introduction

Interpretation:

For the given equation ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$, the balanced molecular equation has to be written.

Concept Introduction:

Balancing the equation:

• There is a Law for conversion of mass in a chemical reaction i.e., the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the skeletal reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Place suitable coefficients in front of reactants as well as products until the number of atoms on each side (reactants and products) becomes equal.

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Balancing the chemical Equation:

Count the number of atoms on each side of the reaction.

Atom	Reactant side	Product side
$\text{C}$	2	4
$\text{H}$	6	8
$\text{O}$	4	5
$\text{Ba}$	1	1

Place suitable coefficient before reactants and products and then check for the number of atoms again.

  ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Atom	Reactant side	Product side
$\text{C}$	4	4
$\text{H}$	10	10
$\text{O}$	6	6
$\text{Ba}$	1	1

The number of atoms of present on each side of the reaction is same.  Hence, the balanced equation for the given reaction is ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

(c)

Interpretation Introduction

Interpretation:

The net ionic equation for the reaction of ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$ has to be written.

Concept Introduction:

Net ionic Equation:

The net ionic equation shows only those chemical species that actually undergo chemical change.  The ions that do not change during the chemical reaction are called spectator ions.  These spectator ions are not shown in net ionic equation.

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Net Ionic Equation:

Write the balanced molecular equation.

  ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

Write the ionic equation of the above reaction as follows,

  ${\text{2CH}}_{\text{3}}{\text{COO}}^{-}{}_{\text{(aq)}}{\text{ + 2H}}^{+}{}_{(aq)}+{\text{Ba}}^{2+}{}_{(aq)}+2{\text{OH}}^{\text{-}}{}_{(aq)}\stackrel{}{\to }{\text{Ba}}^{2+}{}_{\text{(aq)}}{\text{ + 2CH}}_{\text{3}}{\text{COO}}^{-}{}_{(aq)}+{\text{2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

${\text{Ba}}^{2+}$ and ${\text{CH}}_{\text{3}}{\text{COO}}^{-}$ appear on both sides of the equation and are spectator ions.  Hence, cancel the spectrator ion since they remain unchanged during the course of the reaction.

  $\cancel{{\text{2CH}}_{\text{3}}{\text{COO}}^{-}{}_{\text{(aq)}}}{\text{ + 2H}}^{+}{}_{(aq)}+\cancel{{\text{Ba}}^{2+}{}_{(aq)}}+2{\text{OH}}^{\text{-}}{}_{(aq)}\stackrel{}{\to }\cancel{{\text{Ba}}^{2+}{}_{\text{(aq)}}}\text{ + }\cancel{{\text{2CH}}_{\text{3}}{\text{COO}}^{-}{}_{(aq)}}+{\text{2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The positive charge on hydride ion and negative charge on hydroxide ion cancel each other.  Thus, the net charge on both sides of the reaction are zero.  The number of atoms on both sides of the reaction are same.

Hence, the net ionic equation of the given reaction is,

  ${\text{2H}}^{+}{}_{(aq)}+2{\text{OH}}^{\text{-}}{}_{(aq)}\stackrel{}{\to }{\text{2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

(d)

Interpretation Introduction

Interpretation:

The number of moles of acetic acid that is represented by $\text{6}\text{.00 g}$ of acetic acid has to be calculated.

Concept Introduction:

Moles:

Mole of the substance is found by dividing the mass of the substance by its molar mass.

  $\text{No}\text{. of moles (n) = }\frac{\text{mass}}{\text{Molar mass}}$

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The mass of acetic acid is $\text{6}\text{.00 g}$

Calculation of number of atoms:

The molar mass of acetic acid is $\text{60}\text{.052 g/mol}$

Determine the moles of methionine present in given amount of methionine as follows,

  $\begin{array}{l}\text{moles}\text{= }\frac{\text{mass}}{\text{Molar mass}}\\ =\frac{\text{6}\text{.00 g}}{\text{60}\text{.052 g/mol}}\\ =0.0999\text{ moles}\end{array}$

The number of moles of acetic acid present is $0.0999\text{moles}$

(e)

Interpretation Introduction

Interpretation:

The number of moles of Barium hydroxide that must be present for the complete reaction to occur has to be given.

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The balanced equation for this given reaction can be written as,

  ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

From the stiochiometry of the reaction equation, it is known that two moles of acetic acid reacts with one mole of Barium hydroxide.

Hence, the number of moles of Barium hydroxide that is required for the complete reaction to occur is ${\text{1 mol Ba(OH)}}_{\text{2}}$.

(f)

Interpretation Introduction

Interpretation:

The number of moles of water produced in the given reaction has to be given.

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The balanced equation for this given reaction can be written as,

  ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

From the stiochiometry of the reaction equation, it is known that two moles of acetic acid reacts with one mole of Barium hydroxide and produces one mole of barium acetate and two moles of water as product.

Hence, the number of moles of water produced in the given reaction is $2{\text{ mol H}}_{\text{2}}\text{O}$.

(g)

Interpretation Introduction

Interpretation:

The amount (in $\text{g}$) of water produced in the given reaction has to be calculated.

Concept Introduction:

Mass:

Mass of the compound is calculated by mole of the compound multiplied with molar mass of the compound.

  $\text{Mass}\text{=}\text{Molar}\text{mass}\text{×}\text{mole}$

Explanation of Solution

Given:

Acetic acid reacts with Barium hydroxide and produces barium acetate and water.  The skeletal equation of the reaction is,

  ${\text{CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

The balanced equation for this given reaction can be written as,

  ${\text{2CH}}_{\text{3}}{\text{COOH}}_{\text{(aq)}}{\text{ + Ba(OH)}}_{\text{2(aq)}}\stackrel{}{\to }{\text{ Ba(CH}}_{\text{3}}{\text{COO)}}_{\text{2(aq)}}{\text{ + 2H}}_{\text{2}}{\text{O}}_{\text{(l)}}$

From the stiochiometry of the reaction equation, it is known that two moles of acetic acid reacts with one mole of Barium hydroxide and produces one mole of barium acetate and two moles of water as product.

Hence, the number of moles of water produced in the given reaction is $2{\text{ mol H}}_{\text{2}}\text{O}$.

The molar mass of water is $\text{18}\text{.015 g/mol}$.

Determine the mass of water formed as follows,

  $\begin{array}{l}\text{Mass}\text{=}\text{ Molar}\text{mass}\text{×}\text{mole}\\ \text{= 18}\text{.015 g/mol}\times 2{\text{ mol H}}_{\text{2}}\text{O}\\ =36.03\text{ g}\\ \approx \text{ 36}{\text{.0 g H}}_{\text{2}}\text{O}\end{array}$

Therefore, the mass of water produced is $\text{36}\text{.0 g}$