What is meant by bond energy?

The enthalpy change of a reaction is calculated as: ΔH = energy .......... (bonds broken) − energy .......... (bonds formed).

Explain, in terms of bond energies, what determines whether a reaction is exothermic or endothermic overall.

True or False? If the enthalpy change (ΔH) of a reaction is positive, more energy was absorbed breaking bonds than was released forming bonds.

Describe the method for calculating the enthalpy change of a reaction using bond energies.

Bond .......... is always exothermic. Bond .......... is always endothermic.

True or False? Energy is needed to form new chemical bonds during a reaction.

Define an exothermic reaction.

True or False? In an exothermic reaction, the temperature of the surroundings increases.

In an exothermic reaction, thermal energy is transferred .......... the surroundings. In an endothermic reaction, it is taken .......... the surroundings.

Define an endothermic reaction.

True or False? In an endothermic reaction, the temperature of the reaction mixture increases because energy is absorbed.

Why does the temperature of the surroundings decrease during an endothermic reaction?

A sporting injury cold pack uses an .......... reaction, causing the temperature of the pack to ...........

True or False? Combustion and neutralisation are both examples of exothermic reactions.

Define activation energy (Ea).

True or False? The enthalpy change (ΔH) is positive for an exothermic reaction.

For an endothermic reaction, ΔH is ........... For an exothermic reaction, ΔH is ...........

True or False? On a reaction pathway diagram, the initial rise in energy from the reactants represents the activation energy (Ea).

Why do some reactions require more energy to start than others?

On a reaction pathway diagram, four features must be labelled: reactants, products, the .......... energy (Ea) and the .......... change (ΔH).

In a reaction pathway diagram for an exothermic reaction, where are the products positioned relative to the reactants?

True or False? Activation energy (Ea) is the maximum energy that colliding particles must have in order to react.