Enthalpy Changes
Chemistry ⇒ Thermochemistry and Energetics
Enthalpy Changes starts at 10 and continues till grade 12.
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See sample questions for grade 11
A chemical reaction has an enthalpy change of +75 kJ mol-1. Will the temperature of the surroundings increase or decrease?
A reaction has ΔH = -200 kJ mol-1. If the reaction is reversed, what is the enthalpy change for the reverse reaction?
A student mixes 50.0 g of water at 25.0°C with 50.0 g of water at 75.0°C in an insulated container. Assuming no heat loss, what is the final temperature? (Specific heat capacity of water = 4.18 J g-1 K-1)
Calculate the enthalpy change for the reaction: C(s) + O2(g) → CO2(g), given the following data:
C(s) + 1/2 O2(g) → CO(g) ΔH = -110 kJ mol-1
CO(g) + 1/2 O2(g) → CO2(g) ΔH = -283 kJ mol-1
Calculate the enthalpy change when 0.5 mol of methane is burned, given that the standard enthalpy of combustion of methane is -890 kJ mol-1.
Calculate the heat evolved when 2.00 mol of H2O(l) is formed from H2(g) and O2(g). Given: 2H2(g) + O2(g) → 2H2O(l) ΔH = -572 kJ.
Define the term 'standard enthalpy change of combustion'.
Describe the difference between enthalpy of atomization and enthalpy of formation.
Explain why bond breaking is endothermic and bond making is exothermic.
Explain why the enthalpy change of neutralization for strong acids and bases is almost the same.
Explain why the enthalpy change of vaporization is always positive.
If the enthalpy change for a reaction is +150 kJ mol-1, is the reaction endothermic or exothermic?
State Hess's Law.
State the conditions for standard enthalpy changes.
