Chapter 11, Problem 53A

(a)

Interpretation Introduction

Interpretation:

The tube needs to be determined which contains the sodium metal when pieces of sodium and magnesium are dropped into separate water-filled test tubes (A and B) and there is vigorous bubbling in Tube A but not in Tube B.

Concept Introduction:

A chemical reaction in which two or more products are produced by one reactant is called a decomposition reaction and the general form of such reaction is $\text{AB}\to \text{A}+\text{B}$ .

Answer to Problem 53A

The sodium metal is in tube A.

Explanation of Solution

There is a reaction of sodium with water in tube A as $\text{Na}\left(\text{s}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to \text{NaOH}\left(\text{aq}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$ where the products are sodium hydroxide and hydrogen gas.

There is a reaction of magnesium with water in tube B as $\text{Mg}\left(\text{s}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to \text{Mg}{\left(\text{OH}\right)}_2\left(\text{aq}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$ where the products are magnesium hydroxide and hydrogen gas.

The vigorous bubbling is a result of a reaction between sodium and water, thus, tube A contains sodium metal.

(b)

Interpretation Introduction

Interpretation:

The equation needs to be determined for the tube which contains the sodium metal and determine the type of reaction that occurs in this tube.

Concept Introduction:

A chemical reaction in which two or more products are produced by one reactant is called a decomposition reaction and the general form of such reaction is $\text{AB}\to \text{A}+\text{B}$ .

Answer to Problem 53A

The reaction from tube A is $\text{2Na}\left(\text{s}\right){\text{+2H}}_{\text{2}}\text{O}\left(\text{l}\right)\to 2\text{Na}\left(\text{OH}\right)\left(\text{aq}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$ and the type of reaction is single displacement reaction.

Explanation of Solution

There is a reaction of sodium with water in tube A as $\text{Na}\left(\text{s}\right){\text{+H}}_{\text{2}}\text{O}\left(\text{l}\right)\to \text{NaOH}\left(\text{aq}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$ where the products are sodium hydroxide and hydrogen gas.

So, the equation is $\text{2Na}\left(\text{s}\right){\text{+2H}}_{\text{2}}\text{O}\left(\text{l}\right)\to 2\text{Na}\left(\text{OH}\right)\left(\text{aq}\right){\text{+H}}_{\text{2}}\left(\text{g}\right)$ .

The above reaction is an example of a single displacement reaction.