Question

There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. In the first step, calcium carbide and water react to form acetylene and calcium hydroxide: (s) (g) (g) (s) In the second step, acetylene, carbon dioxide and water react to form acrylic acid: (g) (g) (g) (g) Calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. Round your answer to the nearest .

Answer 1

Answer:

The net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide is -470.4 kJ/mol.

Explanation:

Step 1 : Calcium carbide and water react to form acetylene and calcium hydroxide

$CaC_2(s)+2H_2O(g)\rightarrow$

             $C_2H_2(g)+Ca(OH)_2(s),\Delta H_1=-414 kJ$..[1]

Step 2 : Acetylene, carbon dioxide and water react to form acrylic acid

$6C_2H_2(g)+3CO_2(g)+4H_2O(g)\rightarrow 5CH_2CHCOOH(g),\Delta H_2=132 kJ$..[2]

Using Hess's law:

[1] × 6 + [2]

$6CaC_2(s)+16H_2O(g)+3CO_2\rightarrow 5CH_2CHCOOH(g)+6Ca(OH)_2(s),\Delta H_3=?$

$\Delta H_3=6\times \Delta H_1+\Delta H_2$

$\Delta H_3=6\times (-414 kJ)+132 kJ=-2352 kJ$

The energy released on formation of 5 moles of acrylic acid = -2352 kJ

The energy released on formation of 1 moles of acrylic acid :

$=\frac{-2352 kJ}{5 mol}=-470.4 kJ/mol$

Hence, the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide is -470.4 kJ/mol.