Compounds and mixtures
Names and Formulae
- salt=sodium chloride=sodium, chlorine
- chalk=calicium carbonate=calcium,carbon,oxygen
- limestone=calcium carbonate=calcium,carbon,oxygen
- natural gas=methane=carbon,hydrogen
Reactant=substances at the start of the readtion
Product=substance that the reaction produces
Reactions and compounds
chemical reaction could be happening if a gas is produced, the colour changes, heat is produced, there is a change is mass, there is a change in appearance.
Compounds and mixtures 2
Different types of reactions
- combustion= reactions with oxygen including burning
- neutralisation= when an acid reacts with an alkali they are cancelled out and become neutral
- precipitaion= in a reaction with two solutions one of the products is insoluble and settles as a solid called a precipitate.
- thermal decoposition= when you heat some compounds they vreak down or decompose
A mixture is not pure, a mixture contains more than one substance, it contains more than one particle, the particles are not joined toghether they are just mixed, seawater,tes and air are all types of mixtures.
- oxygen=21% water=between 01% and 6.0%
- argon(and other noble gases)=1%
Compounds and mixtures 3
separtion of the air
The air is separated by using fractional distillation. This is where you cool the air until all the particles end up turning into a solid or liquid, then you heat it back up and as they all have different melting points you can collect the gas given off at different times and then you have separated the air.
Melting point= going from solid to liquid
Boiling point= going from liquid to gas
An element has a fixed melting and boiling point as it only conatins on set of particles but a mixture doesnt have a set melting point as it is made up of different particles which all have different melting points it will range from one temp to another.
4000 million years ago the air was different it contained mainly CO2, very little oxygen, small amount of gases like methane and ammonia and some water vapour.
Compounds and mixtures 4
The air is still changing because over the last 200 years humans have started using fossil fuels which cause CO2 into the air which for a while was ok as the plants were taking it in and breathing out oxygen but they cant do that for ever.
Sustainable deveolopement is where people need to stop using materials that can't be replaced and start recycling which from that we can create for sustainable materials for energy etc. We also need to build more houses as the growing demand of living space is overwhelming. But we need to do all of this without affecting the enviroment.
In a lab we just do metal ore+carbon=CO2+Metal which is fine on a small scale, but when you start doing it on a large scale you need a lot of ore which costs money and creates a lot f pollution.