1- Principles Of Chemistry

Question 1

Define solvent

Answer 1

Liquid the solute is dissolved into

Question 2

Define Solute

Answer 2

The substance being dissolved

Question 3

Crystallisation

Answer 3

Pour solution in evaporating dish, heat gently

Evaporate the water, solution +concentrated

When crystals appear remove from heat

Filter and dry

Question 4

Equation for solubility

Answer 4

= (mass of solid/ Mass of water removed) x100

Question 5

Simple distillation

Answer 5

Liquid from solution

Heat until substance with lowest boiling point evaporates

Cooled condensed collected

Boiling points must be very different

Question 6

Fractional distillation

Answer 6

Use a flask and fractionating column

Heat, as they evaporate at diff temperatures

They rise as they evaporate to top

Use cold water as a condenser

Continue for all stages

Question 7

Chromatography

Answer 7

Draw baseline in pencil

Add spots and place in solvent (eg water) (makes sure solvent is below base line)

Question 8

Equation for Rf value (ratio of distances travelled)

Answer 8

Distance traveled by solute/ distance travelled by solvent

Question 9

Define isotope

Answer 9

Form of the same element with a different number of NEUTRONS

Question 10

Find Ar from isotopes

Answer 10

Turn each percentage into decimal

Multiply by mass number (changed number)

Add together

Question 11

Groups are…. (V/h)

Answer 11

Vertical

Question 12

What do elements of the same group have in common?

Answer 12

Same number of electrons on outershell

Question 13

Moles, mass, Mr equation

Answer 13

Moles= mass/Mr

Question 14

Calculate reacting masses ( Pg 23 CGP)

Answer 14

Write balanced equation

Work out Mr (of what ur interested in)

Calculate number of moles

Look at the ratio of moles

Calculate the mass (of the moles of the substance)

Question 15

Empirical formula

Answer 15

Elements
Mass
Moles
Ratio

Question 16

Ionic -electrostatic static attractions

Answer 16

Oppositely charged ions are strongly attracted to each other

Question 17

Giant Ionic Lattice

Answer 17

Strong electrostatic attractions, strongly packed

Need large amount of energy to overcome (/break) these attractions

Don’t conduct as solids, only melted or dissolved (in water)

Question 18

Covalent- electrostatic attractions

Answer 18

Strong attraction between the shared electron and the positive nuclei

Question 19

Why are simple molecular structures liquids or gases, or solids with low boiling points?

Answer 19

They have weak intermolecular forces, which need little energy to overcome (/break) them

Question 20

Giant covalent structures

Answer 20

No charged ions

Lots of strong bonds

More energy needed to overcome (/break) the bonds

Don’t conduct (-graphite)

Usually insoluble

Question 21

Diamond

Answer 21

Each C has four bonds

Strong bonds

Rigid lattice structure (hard)

Doesn’t conduct (no free electrons or ions)

Question 22

Graphite

Answer 22

Each C has 3 bonds

Creates layers held weakly by intermolecular forces

High melting point (covalent bonds in layers)

Conducts (one delocalised electron)

Question 23

C60 Fullerene

Answer 23

Held weakly by intermolecular forces (can slide, is soft)

One delocalised electron but cannot move between molecules and so is A POOR CONDUCTOR

Question 24

Is group 1 acid or alkali?

Answer 24

Alkali

Question 25

Reaction- lithium and water

Answer 25

Fizzes steadily, becomes smaller until all reacted Least reactive

Question 26

Reactions- sodium and water

Answer 26

Forms a ball, fizzes more rapidly, quickly becomes smaller until disappears 2nd most/ least reactive

Question 27

Potassium

Answer 27

Forms a ball (melts) quickly, fizzes, possibly burns (with a lilac flame), (and sometimes reacts with an explosion)

Question 28

Chlorine at room temperature

Answer 28

Atomic number,17 Colour- green State- gas Boiling point- -34

Question 29

Bromine at room temp

Answer 29

Atomic number-36 Colour- red brown State- liquid Boiling point - 59C

Question 30

Iodine at room temp

Answer 30

Atomic number- 53 Colour- dark grey State- solid Boiling point- 185C

Question 31

What's a displacement reaction?

Answer 31

A more reactive element displaces ( or pushes out) a less reactive element (Can be used to find out what is more/ less reactive) Eg chlorine water + potassium iodide forms potassium chloride (chlorine is more reactive)

Question 32

What are the four main gases, and their percentages, in air?

Answer 32

78% nitrogen 21% oxygen >1% argon 0.04% carbon dioxide

Question 33

Combustion of magnesium

Answer 33

Burns with a bright white flame Forms white powder / magnesium oxide Slightly alkaline when dissolved in water

Question 34

Combustion of hydrogen

Answer 34

Orange/ yellow flame Water vapour as only product

Question 35

Combustion of sulphur

Answer 35

Pale blue flame Produces sulphur dioxide Acidic when dissolved in water

Question 36

Thermal decomposition of metal carbonates

Answer 36

Produces CO2 and a metal oxide Substance broken down when heated Use copper (II) carbonate and a delivery tube

Question 37

Acid + metal goes to...

Answer 37

Salt + hydrogen

Question 38

Metal + water goes to...

Answer 38

Metal hydroxide + hydrogen

Question 39

A sacrificial method of preventing rust

Answer 39

Coat with Zinc ( which is more reactive) Called galvanising

Question 40

Define oxidising agent

Answer 40

The substance that is reduced (oxidises other substance)

Question 41

Define reducing agent

Answer 41

The substance that is oxidised (reduces the other substance)

Question 42

Indicators- litmus paper

Answer 42

Red in acid Blue in alkaline Purple in neutral

Question 43

Indicators- phenolphthalein

Answer 43

Colourless in acid Pink in alkaline

Question 44

Indicators- Methyl orange

Answer 44

Red in acid Yellow in alkaline

Question 45

Acids in solutions are a source of...

Answer 45

Hydrogen ions

Question 46

Alkalis in solutions are a source of...

Answer 46

Hydroxide ions