Chemistry Unit 8 Enthalpy of reactions...
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Name: ___________ Total: ____/30 Chemistry Unit 8 Enthalpy of reactions worksheet 1. (1 mark each)Classify each of the following reactions as either exothermic or endothermic. a 2H 2 O(l) → 2H 2 (g) + O 2 (g); ΔH = +572 kJ mol 1- Exothermic/endothermic b NH 4 NO 3 (s) → NH 4 NO 3 (aq); ΔH = +25 kJ mol 1 Exothermic/endothermic c Mg(s) + Cl 2 (g) → MgCl 2 (s); ΔH = 644 kJ mol 1 Exothermic/endothermic d NaOH(aq) + HCl(aq) → NaCl(aq) + H 2 O(l); ΔH = 57 kJ mol 1 Exothermic/endothermic e 2C 2 H 5 OH(l) + 7O 2 (g) → 4CO 2 (g) + 6H 2 O(l); ΔH = 2734 kJ mol 1 Exothermic/endothermic f NaCl(s) → Na + (g) + Cl (g); ΔH = +230 kJ mol 1 Exothermic/endothermic 2. (1 mark each) When a spark is introduced to a vessel containing a mixture of hydrogen and oxygen gases, they react explosively to form water vapor. a State the role of the spark in this chemical reaction. b State which chemical bonds are broken when this reaction is initiated. c State which bonds are generated when the product is formed. d (2 marks) State whether this reaction is endothermic or exothermic. Explain your reasoning. 3. (1 mark each) When 10.0 g of ammonium nitrate is dissolved in 100 cm3 of water, the temperature of the solution decreases from 19.0°C to 10.5°C. a Compare the total enthalpy of the reactants with that of the products and state which is greater. b Classify this reaction as endothermic or exothermic. c State which chemical bonds were broken when the ammonium nitrate dissolved in the water.
Transcript of Chemistry Unit 8 Enthalpy of reactions...
Name: ___________ Total: ____/30
Chemistry Unit 8 Enthalpy of reactions worksheet
1. (1 mark each)Classify each of the following reactions as either exothermic or endothermic. a 2H2O(l) → 2H2(g) + O2(g); ΔH = +572 kJ mol 1- Exothermic/endothermic
b NH4NO3(s) → NH4NO3(aq); ΔH = +25 kJ mol 1 Exothermic/endothermic
c Mg(s) + Cl2(g) → MgCl2(s); ΔH = 644 kJ mol 1 Exothermic/endothermic
d NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l); ΔH = 57 kJ mol 1 Exothermic/endothermic
e 2C2H5OH(l) + 7O2(g) → 4CO2(g) + 6H2O(l); ΔH = 2734 kJ mol 1 Exothermic/endothermic
f NaCl(s) → Na+(g) + Cl (g); ΔH = +230 kJ mol 1 Exothermic/endothermic
2. (1 mark each) When a spark is introduced to a vessel containing a mixture of hydrogen and oxygen gases, they react explosively to form water vapor. a State the role of the spark in this chemical reaction. b State which chemical bonds are broken when this reaction is initiated. c State which bonds are generated when the product is formed. d (2 marks) State whether this reaction is endothermic or exothermic. Explain your reasoning. 3. (1 mark each) When 10.0 g of ammonium nitrate is dissolved in 100 cm3 of water, the temperature of the solution decreases from 19.0°C to 10.5°C. a Compare the total enthalpy of the reactants with that of the products and state which is greater. b Classify this reaction as endothermic or exothermic. c State which chemical bonds were broken when the ammonium nitrate dissolved in the water.
Name: ___________ Total: ____/30
4. (2 marks each) The enthalpy level diagram for the combustion of methane is shown below. Calculate the magnitude and sign of the: a activation energy (Ea) b change in enthalpy (ΔH).
5. Consider the reaction represented by the following equation: A + 2B → C
In this reaction, the total enthalpy of the reactants is 80 kJ mol 1, the total enthalpy of products is 90 kJ mol 1 and the activation energy for the forward reaction is 120 kJ mol 1. a (4 marks) Draw a diagram of the energy profile for this reaction. Label the diagram clearly to show ΔH and Ea. b (1 mark) State whether the forward reaction is endothermic or exothermic. c (1 mark) Calculate the change in enthalpy (ΔH). d (1 mark) Calculate the amount of energy released as the products of the reaction are formed.
e (1 mark) Calculate the activation energy of the reverse reaction: C → A + 2B.
6. With reference to the energy profile diagram shown below, state the magnitude and sign of the activation energy (Ea) and change in enthalpy (ΔH) for the reaction of nitrogen and hydrogen to produce ammonia. a (2 marks) Ea:
b (2 marks) change in enthalpy (ΔH) for the reaction:
