Purity and Seperating Mixture
- Created by: catherinelovesxmen
- Created on: 03-10-19 10:16
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- Purity and Separating Mixtures
- Relative Formula Mass
- RAM= Relative Atomic Mass.
- RAM is the mean mass of an atom of an element compared to 1/12 mass of a carbon-12 atom.
- Chemical formula states how many atoms of each element there are in a unit.
- Relative Formula Mass= Mean mass of a substance compared to 1/12 of a carbon-12 atom.
- RFM isn't found on the periodic table, so this is something you have to work out yourself.
- Empirical Formula
- Simplest whole-number ratio of the atoms of each element in a compound.
- Numbers can be simplified by using the HCF.
- The total number of atoms on the left hand side of an equation must be equal to the right.
- Pure and Impure Substances
- Pure- Something that has not been processed or changed.
- Just one element or compound.
- Impure- A mixture containing one or more element.
- It is difficult to obtain pure It is difficult to substances. Many mixtures are useful materials.
- Impure- Melting point is less than of pure substance.
- Melts over a range of temperatures.
- To determine melting point- Melt substance slowly and stir it as it melts.
- Pure- Something that has not been processed or changed.
- Filtration and Crystallisation
- Solution- One substance dissolves into another.
- Solute- Substance that dissolves.
- Solvent- Substance it dissolves in.
- Soluble- Can dissolve in particular solvent.
- Insoluble- Can't dissolve in particular solvent.
- Filtration separates insoluble substance in the solid state from substances in the liquid state.
- Filtration works as filter paper has tiny holes.
- Larger grains don't pass through.
- Smaller molecules pass through.
- Crystallisation- heat the solution until it becomes saturated.
- When the solution cools, the solubility decreases.
- This forms crystals.
- When the solution cools, the solubility decreases.
- Distillation
- SIMPLE distillation separates a solvent from a solution.
- Relies on solvent having a lower boiling point than solute.
- The solution is heated: solvent boils but solute doesn't.
- Solvent escapes through gas state.
- Solvent is then cooled down back to a liquid state in a condenser.
- Used in labs.
- FRACTIONAL Distillation- Separates TWO OR MORE substances from a mixture.
- This is done through a fractioning column.
- E.g: FD of ethanol-water mixture, ethanol vapour and water vapour both leave liquid mixture.
- In the FC: vapours condense on the inside, heating it up.
- When temp reaches boiling point of ethanol, ethanol vapour can't condense any more. Water can.
- Water droplets fall back into flask, ethanol vapour is cooled down back to liquid state.
- Ethanol the drips into collecting container.
- Water droplets fall back into flask, ethanol vapour is cooled down back to liquid state.
- When temp reaches boiling point of ethanol, ethanol vapour can't condense any more. Water can.
- In the FC: vapours condense on the inside, heating it up.
- SIMPLE distillation separates a solvent from a solution.
- Relative Formula Mass
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