C2.5 Flashcards
What happens regarding energy in chemical reactions?
Energy is transferred to or from the surroundings
Many chemical reactions are accompanied by what?
A temperature change
What do exothermic reactions do?
Transfer heat energy to the surroundings
What is some examples of exothermic reactions?
~ Combustion
~ Self-heating coffee cans
~ Hand warmers
~ Neutralising alkalis with acids
What happens to the temperature in exothermic reactions?
It increases
What happens to the temperature in endothermic reactions?
It decreases
What is the word equation for combustion?
Methane + oxygen -> carbon dioxide + water + heat energy
What is the symbol equation for combustion?
CH4 + 2O2 -> CO2 + 2H2O
What do endothermic reactions do?
Take in heat energy from the surroundings
What are some examples of endothermic reactions?
~ Dissolving ammonium nitrate crystals in water
~ Cooling sprains in sport injuries
~ Thermal decomposition
What is the word equation for dissolving ammonium nitrate crystals in water?
Ammonium nitrate + water -> ammonium nitrate solution
What does it mean if a reaction is reversible?
It will be exothermic one way and endothermic the other way, with the same amount of energy transferred each way
What is a test for water?
If water is added to white anhydrous copper sulphate it will turn blue and release heat
What does anhydrous mean?
Contains no water
Hydrated copper sulphate ->/
Anhydrous copper sulphate + water
