Topic 7 - Energy changes

7.9 Recall that changes in heat energy accompany the following

changes:

a salts dissolving in water

b neutralisation reactions

c displacement reactions

d precipitation reactions

and that, when these reactions take place in solution,

temperature changes can be measured to reflect the heat

changes

● Salts dissolving in water is either exothermic or endothermic

● Neutralisation reaction is exothermic

● Displacement is an exothermic or endothermic reaction

● Precipitation is an exothermic reaction

● if these reactions take place in a solution, you can carry them out in a

polystyrene cup with a lid, and measure the temperature change using a

thermometer

what is an exothermic change or reaction

heat energy is given out

what is an endothermic change/ reaction

when heat energy is taken in

what type of reaction is breaking bonds

endothermic

what reaction is making bonds

exothermic

how do you know if the overall heat energy change for a recation is exothermic

if more heat energy is released in forming bonds

in the products than is required in breaking bonds in the

reactants

How do you know that the overall heat energy change for a reaction is endothermic

if less heat energy is released in forming bonds

in the products than is required in breaking bonds in the

reactants

Calculate the energy change in a reaction given the

energies of bonds (in kJ mol–1)

check book and cognito/lesson materials to practice

what is activation energy

the minimum amount of energy needed to start a reaction

what does a reaction profile for endothermic reactions look like

what does a reaction profile for exothermic reactions look like