# The Mole

1.0 / 5

HideShow resource information

- Created by: bio1423
- Created on: 05-11-13 19:26

Mole formula

Mole = mass over Ar

1 of 46

A mole is

one mole of an element contains 6x10to the 23 atoms and has a mass in grams equal to the relative atomic mass

2 of 46

Empirical formula is

The simplist/ smallest whole number ratio of the atoms of each element in a compound

3 of 46

Molecular formula is

the actual number of atoms of each element in a compound

4 of 46

To work out Empirical formula

Element I mass/g I Ar I mol=mass/Ar I divide by smallest mole

5 of 46

Working out Molecular formula

Mr molecule over emprical formula, or Mr/EF

6 of 46

Water of crystallisation

mass of water = mass of hydrated compound - mass anhydrous coompound

7 of 46

Working out number of waters in hydrous compounds

Substance (compound, H2O mass) I mass/g I Mr I mol=mass/Mr I divide by smallest mol

8 of 46

Working out reacting masses

1. Mole = mass/Mr 2. Deduce mole from Equation 3. Mass = molxMr

9 of 46

Maths V Science

Only use no. sig figs qouted in question or 3s.f.

10 of 46

Standard solution

A solution you know the exact concentration of, used for predicting strength of unknown concentrations

11 of 46

mol =

mol = mass/ Mr

12 of 46

Unit of concentration

mol dm-3

13 of 46

Working out concentration

conc = mol/ vol

14 of 46

Unit of Volume

Always in dm3, turn cm3 into dm3 by dividing by 1000

15 of 46

Mol =

mole = conc x vol

16 of 46

Workingout solution concentrations

1. mol = conc x vol 2. deduce no. moles using equation 3. conc = mol/ vol

17 of 46

Monoprotic acid

Acid that produces 1 H+ ion per molecule. they react 1 to 1 with NaOH. HCL, HNO3

18 of 46

Diprotic acid

Produces 2 H+ per molecule. react 1 to 2 with NaOH. H2SO4, H2C2O4 (ethanedioic acid)

19 of 46

Triprotic acid

produces 3 H+ per molecule. React 1 to 3 with NaOH. H3PO4 (phosphoric acid)

20 of 46

An equation

Na2CO3 + 2HCl --> NaCl + CO2 + H2O

21 of 46

When original solution is 250cm3

Work out mol in the titration, usually 25cm3 (normal method) then x 10.

22 of 46

When an excess of acid was used

Find out mol of unreacted acid; mol NaOH, mol to mol ratio, mol HCl then original mol - leftover = mol reacted

23 of 46

Reasons for low % yield

1. impure substance at start. 2. unexpected side reactions 3. not fully reacted 4. some lost during experiment. 5. reversible/ equilibrium reaction so never 100%

24 of 46

% yield equation

% yield = actual mass over max theoretical mass x100

25 of 46

Theoretical mass

mass predicted by a mole calculation; mole, ratio, mass

26 of 46

Atom economy

measures the overall use of all the atoms you purchase and use

27 of 46

Why is atom economy important

1. want to be using as many atoms as possible from those purchased. 2. waste disposal expensive, so less waste is better.

28 of 46

% atom economy equation

% atom economy = Mr of useful product / Mr total reactants x100

29 of 46

Why all gases have the same volume

Because the volume is determined by the distance between molecules, not the size of molecules.

30 of 46

Ideal gas equation

pV = nRT

31 of 46

Converting degrees C into Kelvin

degrees C + 273 = degrees K, degrees K - 273 = degrees C

32 of 46

T =

T = pV/nR

33 of 46

n=

n = pV/ RT

34 of 46

P =

nRT / V

35 of 46

Unit of pressure

Pascals. x1000 = kPa. x1000000 = MPa

36 of 46

Units of volume

m3 cm3 x 1000000 = m3. dm3 x 1000 = m3

37 of 46

Calculating avogadro's constant

Avogadros number = mass of 1 mol over mass of 1 atom

38 of 46

Percentage error for equipment

% error = + or - actual error / amount used x 100

39 of 46

Burette error

= + or - 0.15cm3 / mean concordant value x 100

40 of 46

Pippette error (10 cm3)

= + or - 0.04 / 10.0 x 100 = + or - 0.40%

41 of 46

Pippette error (25 cm3)

= + or - 0.06 / 25.0 x100 = + or - 0.24%

42 of 46

Balance error

= 0.02/ sample mass x 100

43 of 46

Total apparatus error

= pippette error + burette error + balance error

44 of 46

to reduce % error

1. use a balance of higher resolution 2. increase the mass.

45 of 46

% error of the difference of two values

% error = dfference of values / actual value x 100

46 of 46

## Other cards in this set

### Card 2

#### Front

A mole is

#### Back

one mole of an element contains 6x10to the 23 atoms and has a mass in grams equal to the relative atomic mass

### Card 3

#### Front

Empirical formula is

#### Back

### Card 4

#### Front

Molecular formula is

#### Back

### Card 5

#### Front

To work out Empirical formula

#### Back

## Similar Chemistry resources:

0.0 / 5

1.0 / 5

1.0 / 5

1.0 / 5

0.0 / 5

3.5 / 5

3.0 / 5

1.0 / 5

## Comments

No comments have yet been made