Question

Consider the combustion of acetamide:

4C2H5NO(s)+11O2(g)→8CO2(g)+10H2O(l)+2N2(g)  ΔH=−4738kJ

A) How much heat is released when 200.0 g of carbon dioxide is produced?

B) Acetamide has a density of 1.159 g/mL. What volume of acetamide must be combusted to result in the release of 1250 kJ of heat?

Answer 1

Given, the balanced combustion reaction of acetamide,

4C₂H₅NO(s) + 11O₂(g) 8CO₂(g) + 10H₂O(l) + 2N₂(g) ---------H = -4738 kJ

Part A) Given,

Mass of CO₂ = 200.0 g

Calculating the number of moles of CO₂ from the given mass and molar mass of CO₂,

= 200.0 g CO₂ x ( 1 mol / 44.01 g)

= 4.544 mol CO₂

Now, from the given reaction, calculating the heat released per mole of CO₂

4738 kJ heat is released for 8 mol CO₂, thus,

= 4738 kJ / 8 mol

= 592.25 kJ / mol of CO₂

Now, Calculating the heat released for 4.544 mol CO₂,

= 4.544 mol CO₂ x ( 592.25 kJ / 1 mol)

= 2691.4 kJ

Thus, 2691.4 kJ heat is released when 200.0 g of carbon dioxide is produced.

Part B) Given,

The density of acetamide = 1.159 g/mL

Also given,

Heat released = 1250 kJ

Firstly calculating the heat released by 1 mol of acetamide from the given reaction,

4738 kJ heat is released for 4 mol acetamide, thus,

= 4738 kJ / 4 mol

= 1184.5 kJ /mol of acetamide

Now, using the given heat value and the calculated heat released per mole, calculating the number of moles of acetamide,

= 1250 kJ x ( 1 mol / 1184.5 kJ)

= 1.055 mol acetamide

Converting moles to grams,

= 1.055 mol acetamide x (59.07 g / 1 mol)

= 62.34 g acetamide

Now, using the mass of acetamide and the given density, calculating the volume of acetamide,

= 62.34 g acetamide x ( 1 mL / 1.159 g)

= 53.8 mL acetamide

Thus, 53.8 mL acetamide must be combusted to result in the release of 1250 kJ of heat.