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Topic 9 – Kinetics and Equilibrium
7. Heat Energy of reactions ( ∆H): Determining energy change and ∆H value of a reaction
1. Given the reaction
X2 + 2Y2 --------------- > 2XY2 + 10 KJ
The formation of 2 moles of XY2
1) Releases 10 KJ of heat because the reaction is exothermic
2) Releases 10 KJ of heat because the reaction is endothermic
3) Absorbs 10 KJ of heat because the reaction is exothermic
4) Absorbs 10 KJ of heat, because the reaction is endothermic
2. Given the chemical change
2H2O(l) + 572 KJ < ========= > 2 H2(g) + O2(g)
Teacher Preview Copy
Teacher Preview Copy
This reaction
1) Is endothermic and releases 572 KJ of heat energy
2) Is endothermic and absorbs 572 KJ of heat energy
3) Is exothermic and releases 572 KJ of heat energy
4) Is exothermic and absorbs 572 KJ of heat energy
3. The reaction
A + B ----------------- > C + D + 30 KJ
Has ∆H of
1) +30 KJ because the reaction is endothermic
2) +30 KJ because the reaction is exothermic
3) -30 KJ because the reaction is endothermic
4) -30 KJ because the reaction is exothermic
4. Given the reaction
2C(s) + 2H2(g) + 227 KJ ----------- > C2H2(g)
The heat of reaction, ∆H, is
1) +227 KJ because products have more energy than reactants
2) +227 KJ because products have less energy that reactants
3) -227 KJ because products have more energy than reactants
4) -227 KJ because products have less energy than reactants
5. Given the reaction N2O4(g) + 58 KJ ------------- > 2NO2(g)
What is the approximate heat of formation of 1 moles of NO2(g)
1) -58 KJ 3) -29 KJ
2) +58 KJ 4) +29 KJ
6. Given the reaction N2(g) + 3H2(g) -------------- > 2NH3(g) + 91.8 KJ
What is the heat of reaction, ∆H , for the formation of 4 moles of NH3(g)
1) -91.8 KJ 3) -183.6 KJ
2) +91.8 KJ 4) +183.6 KJ
7. In the reaction 2CO(g) + O2(g) -------------- > 2CO2(g) + 566 KJ
Which is true of the heat of formation of CO2(g)
1) ∆H = + 283 KJ/mole 3) ∆H = + 566 KJ/mole
2) ∆H = - 283 KJ/mole 4) ∆H = - 566 KJ/mole
272 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
Topic 9 – Kinetics and Equilibrium
7. Heat Energy of reactions ( ∆H): Determining energy change and ∆H value of a reaction
1. Given the reaction
X2 + 2Y2 --------------- > 2XY2 + 10 KJ
The formation of 2 moles of XY2
1) Releases 10 KJ of heat because the reaction is exothermic
2) Releases 10 KJ of heat because the reaction is endothermic
3) Absorbs 10 KJ of heat because the reaction is exothermic
4) Absorbs 10 KJ of heat, because the reaction is endothermic
2. Given the chemical change
2H2O(l) + 572 KJ < ========= > 2 H2(g) + O2(g)
Teacher Preview Copy
Teacher Preview Copy
This reaction
1) Is endothermic and releases 572 KJ of heat energy
2) Is endothermic and absorbs 572 KJ of heat energy
3) Is exothermic and releases 572 KJ of heat energy
4) Is exothermic and absorbs 572 KJ of heat energy
3. The reaction
A + B ----------------- > C + D + 30 KJ
Has ∆H of
1) +30 KJ because the reaction is endothermic
2) +30 KJ because the reaction is exothermic
3) -30 KJ because the reaction is endothermic
4) -30 KJ because the reaction is exothermic
4. Given the reaction
2C(s) + 2H2(g) + 227 KJ ----------- > C2H2(g)
The heat of reaction, ∆H, is
1) +227 KJ because products have more energy than reactants
2) +227 KJ because products have less energy that reactants
3) -227 KJ because products have more energy than reactants
4) -227 KJ because products have less energy than reactants
5. Given the reaction N2O4(g) + 58 KJ ------------- > 2NO2(g)
What is the approximate heat of formation of 1 moles of NO2(g)
1) -58 KJ 3) -29 KJ
2) +58 KJ 4) +29 KJ
6. Given the reaction N2(g) + 3H2(g) -------------- > 2NH3(g) + 91.8 KJ
What is the heat of reaction, ∆H , for the formation of 4 moles of NH3(g)
1) -91.8 KJ 3) -183.6 KJ
2) +91.8 KJ 4) +183.6 KJ
7. In the reaction 2CO(g) + O2(g) -------------- > 2CO2(g) + 566 KJ
Which is true of the heat of formation of CO2(g)
1) ∆H = + 283 KJ/mole 3) ∆H = + 566 KJ/mole
2) ∆H = - 283 KJ/mole 4) ∆H = - 566 KJ/mole
272 Copyright © 2010 E3 Scholastic Publishing. All Rights Reserved. Survivingchem.com
