Energy Changes Flashcards
Exothermic reaction.
They are accompanied by a temperature rise.
They transfer heat energy from the chemicals to the surroundings. ie give out heat energy.
Endothermic reaction.
They are accompanied by a fall in temperature.
-Heat energy us transferred from the surroundings to the chemicals.
ie take in heat energy.
Investigate the variables that affect temperature changes in reacting solutions. (RP)
1) Set up the equipment as shown.
2) Take the temperature of the acid.
3) Add the metal powder and stir.
4) Record the highest temperature the reaction mixture reaches.
5) Calculate the temperature change for the reaction.
6)Repeat the experiment using different metals.
variables for: Investigate the variables that affect temperature changes in reacting solutions. (RP)
IV=Metal used.
DV=The temperature change.
CV=Concentration and volume of acid.
What is the activation energy?
The minimum amount of energy that the particles must have for a reaction to take place.
What happens in an exothermic reaction?
-Energy is given out to the surroundings.
-The products have less energy than the reactants.
What happens in an endothermic reaction?
-Energy is being taken in from the surroundings.
-The products have more energy than the reactants.
What do catalysts do?
They reduce the activation energy needed for a reaction. This makes the reaction go faster.
Name and endothermic and exothermic reaction.
Breaking a chemical bond requires energy-Its endothermic process.
When a new chemical bond is formed, energy is given out.-Its an exothermic reaction.
How can you measure the amount of energy produced in a chemical reaction in a solution?
By mixing reactants in an insulated container. This enables the temp change to be measured before heat is lost to the surroundings.
Energy change equation.
Energy used to break bonds - energy given out by making bonds.
What happens in a hydrogen fuel cell?
-Hydrogen and oxygen are supplied to the fuel cell.
-The fuel cell is oxidised to produce a potential difference (voltage).
-Overall, the hydrogen is oxidised to form water.
Advantages of fuel cells.
-They produce water, which is non-polluting.
-They are lightweight and small.
-They have no moving parts so are very unlikely to break down.
