0973 05 Chemical Energetics SUPPLEMENT

Front

Give a brief method for investigating how the volume of an alkali affects the temperature changes of a neutralisation reaction.

Back

1. Pour 30 ml of an acid into a polystyrene cup that's sat in a beaker for stability 2. Pour 5 ml of an alkali into the cup, then put the lid on the cup 3. Stir the reaction mixture with a thermometer through the lid 4. Record the highest temp. reached 5. Repeat steps 2-4 until 40 ml of alkali have been added.

Front

Why is a polystyrene cup with a lid used when investigating the temperature changes of a reaction?

Back

To reduce heat escaping from the reaction mixture, a polystyrene cup with a lid is a good insulator of heat.

Front

What is a reaction profile?

Back

A diagram which shows whether the reactants have more or less energy than the products.

Front

What is the activation energy of a reaction?

Back

The minimum amount of energy that colliding particles must have in order for them to react.

Front

Which part of a reaction profile shows the activation energy of a reaction?

Back

from the energy of the reactants to the highest point of the curve

Front

Which part of a reaction profile shows the overall energy change of a reaction?

Back

The difference in energy between the reactants and products.

Front

Define enthalpy change, ∆H, of a reaction.

Back

The transfer of thermal energy during a reaction

Front

What is an exothermic reaction?

Back

A reaction that transfers energy to the surroundings

Front

What does it mean if the overall energy change of a reaction is negative?

Back

the reaction is exothermic

Front

What happens to the temperature of the surroundings during an exothermic reaction?

Back

They increase. The thermometer is included in "the surroundings" so shows the temperature increasing.