Why is a polystyrene cup a preferred container over a metal beaker for measuring the temperature change of an aqueous reaction in a school laboratory?

Polystyrene reacts with the solution to provide more heat

Metal beakers have a specific heat capacity of zero

Polystyrene prevents the activation energy from changing

Polystyrene is a good insulator, minimizing heat loss to the surroundings

Question

True or False: Adding a catalyst to a reaction will change the value of $\Delta H$ (the enthalpy change) for that reaction.

Why does a highly exothermic reaction, such as the combustion of methane, usually require a spark to begin?

What happens to the chemical potential energy of the system during an exothermic reaction?

In a specific chemical reaction, the energy required to break the reactant bonds is $2500 \text{ kJ mol}^{-1}$ and the energy released when new bonds form is $1800 \text{ kJ mol}^{-1}$ . What is the overall enthalpy change () for this reaction?

MYP MYP Chemistry Topic Energy Changes in a Reaction Questionbank

Practice MYP MYP Chemistry Topic Energy Changes in a Reaction with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for Energy Changes in a Reaction and mirrors Paper 1, 2 style where relevant.

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\Delta H

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True

False

To increase the mass of the oxygen particles

To provide the initial activation energy to break reactant bonds

To ensure the products have more energy than the reactants

To make the reaction endothermic

It increases as energy is absorbed from the surroundings

It increases to overcome the activation energy barrier

It decreases as energy is released to the surroundings

It remains constant while kinetic energy increases

$-700 \text{ kJ mol}^{-1}$

$+4300 \text{ kJ mol}^{-1}$

$-4300 \text{ kJ mol}^{-1}$

$+700 \text{ kJ mol}^{-1}$