particles and mixtures / peiodic table and bonding

What is solubility measured in?

Grams of solute per 100 grams of solvent

Set by step on investigation for how temperature affect solubility?

1. Make saturated solution by adding excess amount of solid to 10cm3 of water in boiling tube

2. Stir solution and place tube in 25 degrees Celsius water bath.

3. After 5 min check all excess solid has sunk to bottom and check if solution has reached 25 degrees Celsius.

4. Weigh empty evaporating basin, then pour some solution into basin(no undissolved bits)

5. Re-weigh basin and contents, then gently heat with buns on burner to remove water.

6. Once water is evaporated your left with pure solid, weigh basin and contents.

7. Repeat these steps with different water bath temperatures

Equation for solubility?

Mass of solid / mass of water removed x100

Define electric current?

Flow of electrons or ions

What are ionic compounds made up of?

A lattice of positive and negative ions

When can ionic compounds conduct/not conduct electricity?

Conduct: melts, dissolved

Not conduct: solid

Describe structure of metals?

Giant structure of positive ions surrounded by sea of delocalised electrons.

Held together by electrostatic attraction between nuclei of positive ions and electrons.

Layers of ions can slide over each other, making metals malleable.

How come metals are good conductors of electricity and heat?

Electricity: delocalised electrons are able to move throughout structure. Meaning metals conduct electricity.

Heat: movement of electrons means energy can be transferred quickly throughout material.

Equation and units for concentration?

Concentration = number of moles / volume of solution

(Mol/dm3) = (mol) / (dm3)

How to work out concentration in g/dm3?

Mass/volume

How to work out mass?

Number of moles x Mr(relative formula mass)

Wha is the molar volume at RTP?

24dm3

How to work out volume?

Moles of gas x 24

Define electrolysis?

Breaking down of a substance using electricity.

An electric current is passed through an electrolyte causing it to decompose.

Describe what happens in electrolysis?

Positive ions(cations) move towards cathode(negative electrode) and are reduced.

Negative ions(anions) move towards anode(positive electrode) and are oxidised.

What is a electrochemical cell?

A circuit made up of anode, cathode, electrolyte, a power source and the wires that connect the two electrodes.

How to set up and electrochemical cell for an aqueous solution?

1. Get 2 inert electrodes

2. Clean surface of electrodes using emery/ sand paper.

3. Don’t touch surface as you can transfer grease.

4. Place both electrodes into a beaker filed with electrolyte.

5. Connect electrodes to a power supply using crocodile clips and wires, when power supply turned on a current will flow though cell.

What happens with reactivity as you go down group 1?

Metals are more reactive.

Since outermost electron is in a shell further away from nucleus.

Meaning attraction becomes less.

What happens with reactivity as you go down group 7?

Halogens become less reactive.

Gets harder to attract extra electron to fill outer shell when it’s further away from nucleus.

Atomic radius is larger.

Properties of iron, aluminium and copper?

Dense

Shiny

High tensile strength

Malleable

Uses of iron?

Malleable so used for gates and railings

Uses of aluminium?

Dense so used for aeroplanes

Uses of copper?

Good conductor of heat and electricity so used for heating systems like underfloor heating.

What are titration used for?

Allows you to find out exactly how much acid is needed to neutralise a quantity of alkali.

How to do titration?

1. Use pipettes and pipettes filler, add some alkali To a conical flask with drops of indicator.

2. Fill burette with acid

3. Using burette add acid bit by bit and swirl conical flask.

4. When indicator changes colour all alkali has been neutralised.

5. Record volume of acid used to neutralise alkali.

6. Repeat few times.

How to work out number of moles?

Concentration x volume

How to make lead sulfate?

1. Add 1 spatula of lead nitrate to test tube and add water to dissolve it then shake.

2. In a separate tube do the same with magnesium sulfate.

3. Pour two solutions in beaker and stir, lead sulfate should precipitate out.

4. Get filter paper and filter tunnel and pour solution in conical flask.

5. Swill out beaker with deionised water

6. Rinse contents in filter paper with deionised water so all soluble magnesium nitrate has been washed away.

7. Scrape lead sulfate onto fresh filter paper and leave it to dry in an oven.

How to use titration to make soluble salts from acids/alaklis?

1. Measure set amount of acid into conical flask using pipette and add few drops of indicator.

2. Slowly add alkali to acid using burette until you reach end point, this is when acid’s been neutralised and indicator changes colour.

3. Carry out same reaction with no indicator so salt isn’t contaminated.

4. Solution that remains will only contain salt and water.

5. Slowly evaporate some water and leave solution to crystallise.

6. Filter off solid and dry it where you’ll be left with a pure, dry salt.