States of Matter, Moles and Elements

Question 1

Solid, Liquid. Gas, Aqueous

Answer 1

(s), (l), (g), (aq)

Question 2

Calculating Mr

Answer 2

Sum of all atoms present: E.g. H2O
2 x 1 + 16 = 18

Question 3

Mole:

Answer 3

The unit for amount of a substance

Question 4

Formula for Moles:

Answer 4

Moles = Mass/Mr

Question 5

%yield

Answer 5

actual amount of product/theoretical amount of product

Question 6

Empirical Formula:

Answer 6

The simplest whole number ratio between atoms/ions in a compound
E.g. Pentene C5H10 -> CH2

Question 7

Molecular Formula:

Answer 7

The actual number of atoms of each type of element in a molecule

Question 8

Calculating Empirical Formula

Answer 8

1. Put symbols for each element at top of page
2. Underneath, write masses of each element combining.
3. Divide by their relative atomic mass
4. Divide all the numbers by the smallest of these numbers to give a whole number ratio
5. Use this to give the empirical formula
   (If ratio is 1:1.5 multiply by 2, 1:1.33 x 3, 1:1.25 x 4)

Question 9

Calculating Molecular Formula

Answer 9

1. Calculate mass of empirical formula
2. Find out the number of times the relative mass of the empirical formula goes into the Mr of the compound
3. Multiply the empirical formula by this number

Question 10

Formula for Moles (in solution):

Answer 10

Moles (mol) = concentration (mol/dm^3) x volume (dm^3)

Question 11

cm^3 to dm^3

Answer 11

divide by 1000

Question 12

1 Faraday

Answer 12

96500 C

Question 13

Volume of 1 mole of gas at rtp

Answer 13

24dm^3

Question 14

Solute definition

Answer 14

The substance being dissolved

Question 15

Solvent definition

Answer 15

The liquid in which the substance is being dissolved

Question 16

Solution definition

Answer 16

The liquid formed (solute + solvent)

Question 17

Saturated solution definition

Answer 17

A solution into which no more solute can be dissolved

Question 18

Solubility definition

Answer 18

The maximum mass of a solute that dissolves in 100g of solvent
solubility = mass of solute/mass of solvent x 100

Question 19

Element

Answer 19

A substance made up of only one type of atom

Question 20

Compound

Answer 20

A substance that contains two or more elements chemically joined together in fixed proportions

Question 21

Mixture

Answer 21

Different substances in the same space, but not chemically combined

Question 22

Simple distillation

Answer 22

Used to separate a liquid from a solution
E.g. separating water from salt water
The salt water is boiled; the water vapour condenses back into a liquid when passed through the condenser. The salt is left behind in the flask

Question 23

Fractional distillation

Answer 23

Used to separate a mixture of different liquids with different boiling points
Using a thermometer to monitor the temperature of the fractionating column, by keeping it at a specific temperature, only one liquid boils and its vapour travels up the column, through the condenser and condenses back into a liquid

Question 24

Filtration

Answer 24

Used to separate an insoluble solid from a liquid
E.g. separating sand from a mixture of sand and water
The mixture is poured into the filter paper; the sand does not pass through and is left behind as residue, but the water passes through and is collected in the conical flask (filtrate)

Question 25

Crystallisation

Answer 25

Gently heat solution in an evaporating basin to evaporate some of the water; Until crystals form on a glass rod (shows that a hot saturated solution has formed); Leave to cool and crystallise; Filter to remove the crystals; Dry by leaving in a warm place

Question 26

Paper chromatography

Answer 26

Used to separate parts of a mixture into their components E.g. different dyes in ink can be separated A base line is drawn in pencil (so it doesn't run/smudge like ink) A sample/spot of ink is placed on the base line The paper is lowered into the solvent !! base line must sit above solvent level (or the ink would dissolve in the solvent) The solvent is absorbed into the paper and rises up, carrying the dyes with it Each dye moves up the paper at different rates depending on their solubility Higher solubility = travel further

Question 27

Rf value

Answer 27

Rf = Distance of dye from baseline / Distance of solvent front from baseline Always between 0 and 1