Chemistry Paper 1: Energy Changes Flashcards
What are exothermic reactions?
Energy is given out to the surrounding so the temperature of the surroundings increases
What are some examples of exothermic reactions?
.neutralisation
.oxidation
What do energy profile diagrams do?
Represent the energy changes that take place in reactions
What does the difference between the energy of reactants and the energy of the products tell us?
The energy that has been released to the surroundings
How can exothermic reactions be useful?
.they are found in hand warmers and self heating cans
What are endothermic reactions?
Energy is taken in from surroundings so the temperature of the surroundings decreases
What do endothermic and exothermic reactions have In common?
Both energy rises to a peak
What is activation energy?
minimum amount of energy that particles must have in order to react
Why are exothermic reactions negative?
Because energy has been transferred from the chemicals
Why are endothermic reactions positive?
Because energy has been gained
What type of reactions is it when a chemical bond is broken and why?
Endothermic because it requires energy
What type of reaction is it when we make bonds and why?
Exothermic because it releases energy
What is the independent variable (changed) in the temperature changes required practical?
Volume of sodium hydroxide
What is the dependant variable (measured) in the temperature changed practical?
Maximum temperature reached?
What are the three control variables (stays the same) in the temperature changes practical?
Volume of hydrochloric acid, concentration of hydrochloric acid, concentration of hydroxide solution
