Chemistry
- Created by: AOconnor
- Created on: 14-05-18 18:25
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- Chemistry
- Equations
- Half equations
- Show what happens to a reactant in a reaction
- Electrons written as e-
- Fe ---> Fe(2+) + 2e(-)
- Ionic equations
- Used to simplify equations
- Only show species involved in reaction
- Spectator ions aren't included
- AgNO3 + NaCL ---> AgCl + NaNO3
- Ag(+) + Cl(-) ---> AgCl
- Species refers to different atoms/molecules/ions involved in reaction
- Half equations
- Conservation of mass
- Law states that total mass of products is equal to total mass of reactants
- No atoms created or destroyed
- There can be apparent changes of mass
- This occurs when a reaction happens in a non-closed system and a gas can enter/leave
- When magnesium burns in air to produce magnesium oxide the mass increases because it combines with the oxygen in the air
- This occurs when a reaction happens in a non-closed system and a gas can enter/leave
- Law states that total mass of products is equal to total mass of reactants
- Amount of substances
- Mole is a measure of the number of particles contained in a substance
- One mole contains the same number of particles (Avogadro's constant)
- 6.02 x 10(23)
- Mol = mass/Ar
- One mole contains the same number of particles (Avogadro's constant)
- Limiting Reactants
- When a chemical reaction stops it is because one reactant is completely used up
- This is the limiting reactant
- The other reactant is said to be in excess
- This is the limiting reactant
- When a chemical reaction stops it is because one reactant is completely used up
- Concentration of solutions
- Concentration = mol/volume
- Mole is a measure of the number of particles contained in a substance
- Energy Transfers
- Exothermic
- Heat energy transferred to surroundings
- Temperature rise
- Negative energy change
- Combustion, oxidation and neutralisation reactions
- Heat energy transferred to surroundings
- Endothermic
- Heat energy taken in from surroundings
- Temperature fall
- Positive energy change
- Thermal decomposition reactions
- Heat energy taken in from surroundings
- Energy changes in reactions
- In exothermic, the nergy required to break bonds is less than the energy released when new bonds are fromed
- Excess energy released to surroundings
- In endothermic, the energy required to break bonds is more than the energy released when new bonds are formed
- Requires energy so it takes it from the surroundings
- Catalysts reduce activation energy and make the reaction go faster
- In exothermic, the nergy required to break bonds is less than the energy released when new bonds are fromed
- Exothermic
- Equations
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