Question

Write reactions that correspond to the following enthalpy changes:

a. ΔH°_f for solid aluminum oxide

b. the standard enthalpy of combustion of liquid ethanol [C₂H₅OH(l)]

c. the standard enthalpy of neutralization of barium hydroxide solution by hydrochloric acid

d. ΔH°_f for gaseous vinyl chloride [C₂H₃Cl(g)]

e. the enthalpy of combustion of liquid benzene [C₆H₆(l)]

f. the enthalpy of solution of solid ammonium bromide

Short answer

a.$2Al\left(s\right)+\frac{3}{2}{O}_2\left(g\right)\to A{l}_2{O}_3\left(s\right)$

b.$C_2{H}_{5}OH\left(l\right)+3O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(l\right)a$

c.$HCl+\frac{1}{2}Ba{\left(OH\right)}_2\to \frac{1}{2}BaC{l}_2+H_{2}O$

d.$2C\left(s\right)+\frac{3}{2}{H}_2\left(g\right)+\frac{1}{2}C{l}_2\left(g\right)\to C_2{H}_{3}Cl\left(g\right)$

e.$C_6{H}_6\left(l\right)+\frac{15}{2}{O}_2\left(g\right)\to 6C{O}_2\left(g\right)+3H_{2}O\left(l\right)$

f.$N{H}_{4}Br\left(s\right)+H_{2}O\left(l\right)\to N{H}_{4}Br\left(aq\right)$

Step-by-step solution

Equation for ΔH°f for solid aluminum oxide

ΔH°_frepresents standard heat of formation and it is the amount of heat which is absorbed or evolved when one mole of a compound is formed from its constituent elements, each of substance should be in its normal physical state i.e., gas, liquid, or solid.

So, the reaction for ΔH°_ffor solid aluminum oxide is

$2Al\left(s\right)+\frac{3}{2}{O}_2\left(g\right)\to A{l}_2{O}_3\left(s\right)$

Equation for the standard enthalpy of combustion of liquid ethanol [C2H5OH(l)]

The standard enthalpy of combustion of a substance is the amount of heat energy that is given out when one mole of a substance burns completely to form carbon dioxide and water on reacting with oxygen.

.$C_2{H}_{5}OH\left(l\right)+3O_2\left(g\right)\to 2C{O}_2\left(g\right)+3H_{2}O\left(l\right)$

Equation for the standard enthalpy of neutralization of barium hydroxide solution by hydrochloric acid

It isthe enthalpy change when solutions of HCl and Ba(OH)₂ react together under standard conditions to produce 1 mole of water.

So equation for this is given as :

$HCl+\frac{1}{2}Ba{\left(OH\right)}_2\to \frac{1}{2}BaC{l}_2+H_{2}O$

Equation for ΔH°f for gaseous vinyl chloride

This can be written as

$2C\left(s\right)+\frac{3}{2}{H}_2\left(g\right)+\frac{1}{2}C{l}_2\left(g\right)\to C_2{H}_{3}Cl\left(g\right)$

Equation for the standard enthalpy of combustion of liquid benzene[C6H6(l)]

This can be written as

$C_6{H}_6\left(l\right)+\frac{15}{2}{O}_2\left(g\right)\to 6C{O}_2\left(g\right)+3H_{2}O\left(l\right)$

Equation for the enthalpy of solution of solid ammonium bromide

The enthalpy of solution is the change in enthalpy which takes place on the dissolution of a substance in a solvent at constant pressure resulting in infinitedilution.

$N{H}_{4}Br\left(s\right)+H_{2}O\left(l\right)\to N{H}_{4}Br\left(aq\right)$