Classifying materials compounds mixtures metals and non metals Flashcards
What is this?
An element - all the atoms are the same but it is made from molecules
eg oxygen, chlorine
What is this
An element made of atoms they are not joined together
What is this
A compound two or more different atoms joined together
What is this
A mixture mad from an element and a compound they are not joined together
Compounds are formed from…..
Chemical reactions
What is a chemical reaction?
chemical combine together or split apart to form new substances
State the name of the substances you start with in a chemical reaction
Reactants
State the name of the substances you end up with in a chemical reaction
Products
Can a chemical reaction be reversed?
Compounds can be split back into their original elements but energy is needed to make this happen
eg iron sulphide ——> iron + Sulfur
If two elements react together then the product is a….
Compound
eg Iron + sulfur = iron sulphide
What two ways can you write equations for chemical reaction?
- Word equation eg Iron + sulfur = iron sulphide
- Symbol equation eg Fe + S = FeS
What do the numbers in a chemical formula tell you?
The number of each atom in the compound
eg H2O
Formulae endings- when only two elements combine the ending is usually ?
~ide eg chloride, flouride, sulphide, bromide
Formulae endings- when three or more elements combine and one of them is oxygen the ending is usually ?
~ate eg sulphate, carbonate, nitrate
What is this substance, CO2?
Carbon dioxide
What is this substance, CH4?
Methane
What is this substance, NaOH
Sodium hydroxide
What is this substance, HCl
Hydrochloric acid
What is a pure substance?
It is made from only one element or only one compound. The compound cannot be made simpler without a chemical reaction
eg pure water is H2O it cannot be made into H and O without a chemical reaction
What is a mixture?
Two or more different substances which are not joined together and can be separated.
Eg salt and sand
Is air an element, compound or mixture?
It is a mixture of different gases such as nitrogen, oxygen and carbon dioxide
One way of making a mixture is dissolving, the name of the solid being dissolved is?
Solute
One way of making a mixture is dissolving, the name of the liquid being dissolved into is?
Solvent
One way of making a mixture is dissolving, the name of the final mixture is?
A solution?
If a solid will dissolve it is called?
Soluble
If a solid will NOT dissolve it is called?
Insoluble
When you cannot dissolve any more solute into the solvent the solution is called?
Saturated
What is solubility?
It is a measure of the amount of solute which can be dissolved
What is a solvent?
When dissolving, it is the name of the liquid being dissolved into
What is a solute?
When dissolving, it is the name of the name of the solid being dissolved
Is dissolving a chemical reaction or a physical change?
Physical change
What happens to the mass in a physical change?
The mass is conserved - it stays the same
You may not be able to see the sugar as you dissolve it in water but it is still there
What is a saturated solution?
A solution where no more solute will dissolve
How does solubility vary with temperature?
The higher the temperature the higher the solubility and more solute will dissolve into the solvent
Why does solubility increase with an increase in temperature?
- The higher the temperature of the solvent the more energy it’s particles have and the faster they move
- The faster moving particles bump into more solute molecules breaking the bonds which hold them together.
If 20g of sugar is dissolved into 100g of water what will be the mass of sugar solution?
120g
How does solubility vary between solvents?
Different solutes are more soluble in some solvents than they are in others.
Eg nail varnish will not dissolve in water but will in acetone
Why is water an important solvent
- Lots of solutes dissolve easily into water
- It is vital in living organisms because dissolved minerals and nutrients are carried around the body and waste products can be taken away.
State some common solvents
Water
Alcohols such as ethanol
Acetone (propanone)
What advantage does ethanol have over water as a solvent
It can dissolve some fats and oils which water can’t.
Give some uses of acetone as a solvent
Nail varnish
Paint thinners
Dissolves superglue
State the four ways you can separate a mixture
1 Evaporation
2 Filtration
3 Chromotography
4 Distillation
What is rock salt?
Salt that has been dug from underground it contains pieces of rock and sand in it which need to be got rid of.
What are the four steps used to separate solid salt from rock salt?
- Grinding - to make the pieces smaller and easier to use
- Dissolving - the salt will dissolve but the sand and rock don’t
- Filtering - the sand and rock cant pass through the tiny holes in the filter paper.
- Evaporate - by boiling off half the water then leaving the rest to evaporate slowly it will make crystals of pure salt
What is a filtrate?
It is solution which passes through filter paper
What is chromatography?
It is a method of separating mixtures of inks and dyes into their different parts
What is this called?
Chromatogram
Describe a method for separating ink using chromatography
- Draw a line in pencil on a piece of filter paper.
- Put dots of the ink you want to separate on to the line
- Put the paper into a beaker with a small amount of solvent at the bottom.
- Each dye will leave a spot
How can you tell which is the same ink from a chromatogram?
The coloured dots will be in the same place for the same ink - different ink will have dots in different places
What sort of mixture can be separated using simple distillation?
A solvent from a solution eg water from an ink solution
What is a Liebig condenser?
A glass tube with a separate outer layer through which water passes.
Vapour which passes into the tube is cooled by the water and condenses into a liquid
What is happening here?
Simple distillation, pure water can be distilled from sea water using this method
What is fractional distillation used for?
Separating mixtures of liquids
Separating crude oil into petrol, diesel and other fuels
A liquid consists of a mixture of 3 liquids.
A boils at 100 degrees C
B boils at 120 degrees C
C boils at 150 degrees C
Describe a method for separating the liquids
1.Set up a beaker containing the mixture with a fractioning column ,a thermometer at the top and a Leibig condenser.
2. Heat the beaker until the thermometer reads 100 degrees and collect the liquid from the condenser in a test tube.
3. Wait until the thermometer reads 120 degrees and collect the second liquid
4. The third liquid is collected when the thermometer reads 150 degrees
Describe how a fractioning column works
The column ensures that only the liquid which boils at the temperature on the thermometer at the top can escape, the other liquids condense and run back down into the flask.
Describe how you could check if water is pure.
Pure water boils at 100 degrees, if it is higher then it contains impurities
How could boiling an unknown liquid help you to identify it?
Pure substances have fixed boiling and freezing points
If it boils at 100 degrees it is likely to be pure water
If it boils at 78 degrees it is likely to be ethanol
What is this a diagram of?
Fractional distillation