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 10
A chemical reaction has ΔH = -250 kJ/mol. What does the negative sign indicate?
A reaction has an enthalpy change of +80 kJ/mol. Will the temperature of the surroundings increase or decrease?
A reaction has ΔH = +150 kJ/mol. Is this reaction endothermic or exothermic?
A student dissolves ammonium nitrate in water and observes the temperature drops. What type of enthalpy change is this?
A student mixes hydrochloric acid and sodium hydroxide in a beaker and notices the temperature increases. What can be said about the enthalpy change of this reaction?
Calculate the enthalpy change for the reaction: 2H2(g) + O2(g) → 2H2O(l), given ΔHfo [H2O(l)] = -286 kJ/mol.
Calculate the enthalpy change for the reaction: C(s) + O2(g) → CO2(g), given ΔHfo [CO2(g)] = -394 kJ/mol.
Calculate the enthalpy change when 2 moles of a substance are burned, given that the enthalpy of combustion is -350 kJ/mol.
Define the term 'standard enthalpy change of combustion'.
Describe the difference between enthalpy of fusion and enthalpy of vaporization.
Describe the difference between exothermic and endothermic reactions in terms of enthalpy change and energy flow.
Describe what is meant by the term 'enthalpy profile diagram'.
Explain why bond breaking is an endothermic process.
Explain why enthalpy changes are measured under standard conditions.
Explain why the enthalpy change of a reaction is different if the physical states of reactants or products are different.
Explain why the enthalpy change of combustion is always negative.
If the enthalpy of the products is lower than that of the reactants, what type of reaction is it?
State Hess's Law.
What is enthalpy change (ΔH)?
