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Empirical Formula

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===About Empirical Formulae===

: The '''empirical formula''' of a [[compound]] may not be the same as the [[Chemical Formula|chemical formula]]:*[[Ethane ]] - [[Chemical Formula]]: C2H<~~sup~~sub>6 , '''Empirical Formula''': CH3*[[Ethene ]] - [[Chemical Formula]]: C2H4 , '''Empirical Formula''' CH2*[[Propene]] - [[Chemical Formula]] C3H6, '''Empirical Formula''' CH2*[[Glucose]] - [[Chemical Formula]] C6H12O6, '''Empirical Formula''' CH2O*[[Lactic Acid]] - [[Chemical Formula]] C3H6O3, '''Empirical Formula''': CH2O

: '''Empirical formulae''' are calculated from the amount of [[atom]]s in a [[Chemical Reaction|chemical reaction]].

: The number of [[atom]]s can be found if you know the [[mass]] of different [[element]]s and the [[Relative Atomic Mass|relative atomic mass]] of the [[element]]s in the [[Chemical Reaction|reaction]].

===Finding the Empirical Formula===

{| class="wikitable"

| style="height:20px; width:200px; text-align:center;" |'''Number of Atoms'''

| style="height:20px; width:200px; text-align:center;" |'''Skeletal Diagram'''

| style="height:20px; width:200px; text-align:center;" |'''Ball and Stick Model'''

|-

| style="height:20px; width:200px; text-align:center;" |100 [[atom]]s of [[Hydrogen]] [[Chemical Reaction|react]] completely with 50 [[atom]]s of [[Oxygen]].

|[[File:SkeletalFormulaButane.png|center|200px]]

|[[File:BallandStickButan12diol.png|center|200px]]

|-

| style="height:20px; width:200px; text-align:left;" |

The [[ratio]] of [[Hydrogen]] [[atom]]s to [[Oxygen]] [[atom]]s

H:O

100:50

2:1

So the '''empirical formula''' is H2O

| style="height:20px; width:200px; text-align:left;" |

In this [[diagram]] there are 4 [[Carbon]] [[atom]]s, 10 [[Hydrogen]] [[atom]]s.

The [[ratio]] of [[atom]]s is:

C:H

4:10

2:5

So the '''empirical formula''' is C2H5

| style="height:20px; width:200px; text-align:left;" |

In this [[diagram]] there are 4 [[Carbon]] [[atom]]s, 10 [[Hydrogen]] [[atom]]s and 2 [[Oxygen]] [[atom]]s.

The [[ratio]] of [[atom]]s is:

C:H:O

4:10:2

2:5:1

So the '''empirical formula''' is C2H5O

|}

{| class="wikitable"

|-

| style="height:20px; width:200px; text-align:center;" |64g of [[Oxygen]] is found to [[Chemical Reaction|react]] completely with 8g of [[Hydrogen]]. Find the '''empirical formula''' for the [[product]].

| style="height:20px; width:200px; text-align:center;" |60g of [[Carbon]] is found to [[Chemical Reaction|react]] completely with 160g of [[Oxygen]]. Find the '''empirical formula''' for the [[product]].

| style="height:20px; width:200px; text-align:center;" |416g of [[Sulphur]] is found to [[Chemical Reaction|react]] completely with [[Oxygen]] to produce 832g of [[product]]. Find the '''empirical formula''' for the [[product]].

|-

| style="height:20px; width:200px; text-align:left;" |State the [[mass]] of all [[reactant]]s.

[[Mass]] of [[Oxygen]] = 64g

[[Mass]] of [[Hydrogen]] = 8g

| style="height:20px; width:200px; text-align:left;" |State the [[mass]] of all [[reactant]]s.

[[Mass]] of [[Carbon]] = 60g

[[Mass]] of [[Oxygen]] = 416g

| style="height:20px; width:200px; text-align:left;" |State the [[mass]] of all [[reactant]]s.

[[Mass]] of [[Sulphur]] = 416g

[[Mass]] of [[Oxygen]] = 416g

|-

| style="height:20px; width:200px; text-align:left;" |Find the number of [[mole]]s of each [[element]].

Number of [[Mole]]s = ([[Mass]]/[[Relative Atomic Mass]])

[[Relative Atomic Mass]] of [[Oxygen]] = 16g

[[Mole]]s of [[Oxygen]] = 64/16

[[Mole]]s of [[Oxygen]] = 4 mole

[[Relative Atomic Mass]] of [[Hydrogen]] = 1g

[[Mole]]s of [[Hydrogen]] = 8/1

[[Mole]]s of [[Hydrogen]] = 8 mole

| style="height:20px; width:200px; text-align:left;" |Find the number of [[mole]]s of each [[element]].

Number of [[Mole]]s = ([[Mass]]/[[Relative Atomic Mass]])

[[Relative Atomic Mass]] of [[Carbon]] = 12g

[[Mole]]s of [[Carbon]] = 60/12

[[Mole]]s of [[Carbon]] = 5 mole

[[Mass]] of [[Oxygen]] = 160g

[[Relative Atomic Mass]] of [[Oxygen]] = 16g

[[Mole]]s of [[Oxygen]] = 160/16

[[Mole]]s of [[Oxygen]] = 10 mole

| style="height:20px; width:200px; text-align:left;" |Find the number of [[mole]]s of each [[element]].

Number of [[Mole]]s = ([[Mass]]/[[Relative Atomic Mass]])

[[Relative Atomic Mass]] of [[Sulphur]] = 32g

[[Mole]]s of [[Sulphur]] = 416/32

[[Mole]]s of [[Sulphur]] = 32 mole

[[Relative Atomic Mass]] of [[Oxygen]] = 16g

[[Mole]]s of [[Oxygen]] = 416/16

[[Mole]]s of [[Oxygen]] = 26 mole

|-

| style="height:20px; width:200px; text-align:left;" |Find the [[Ratio]]:

[[Hydrogen]]:[[Oxygen]]

8:4

2:1

| style="height:20px; width:200px; text-align:left;" |Find the [[Ratio]]:

[[Carbon]]:[[Oxygen]]

5:10

1:2

| style="height:20px; width:200px; text-align:left;" |Find the [[Ratio]]:

[[Sulphur]]:[[Oxygen]]

13:26

1:2

|-

| style="height:20px; width:200px; text-align:left;" |The '''empirical formula''' of the [[product]] is H2O

| style="height:20px; width:200px; text-align:left;" |The '''empirical formula''' of the [[product]] is CO2

| style="height:20px; width:200px; text-align:left;" |The '''empirical formula''' of the [[product]] is SO2

|}

===References===

====AQA====

:[https://www.amazon.co.uk/gp/product/0008158762/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158762&linkCode=as2&tag=nrjc-21&linkId=a0fffa35b3ea49a63404f6704e0df7cc ''Formula, formulae; empirical, pages 62-3, 90-1, 252, GCSE Chemistry; Student Book, Collins, AQA '']

====Edexcel====

:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Empirical formula, page 217, GCSE Combined Science, Pearson Edexcel '']

:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Empirical formulae, page 73, GCSE Chemistry, Pearson, Edexcel '']

:[https://www.amazon.co.uk/gp/product/1782948147/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948147&linkCode=as2&tag=nrjc-21&linkId=f63dcd8345f4e49c717b39a228a36c7c ''Empirical formulae, pages 71, 72, 77, 78, GCSE Chemistry, CGP, Edexcel '']

:[https://www.amazon.co.uk/gp/product/1782945725/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945725&linkCode=as2&tag=nrjc-21&linkId=694be7494de75af3349537d34e13f7f0 ''Empirical formulas, pages 27, 30, GCSE Chemistry; The Revision Guide, CGP, Edexcel '']

:[https://www.amazon.co.uk/gp/product/1782945741/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945741&linkCode=as2&tag=nrjc-21&linkId=30da4f2178da182547b62a7329d13b57 ''Empirical formulas, pages 90, 93, GCSE Combined Science; The Revision Guide, CGP, Edexcel '']

====OCR====

:[https://www.amazon.co.uk/gp/product/0198359829/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359829&linkCode=as2&tag=nrjc-21&linkId=90e8d7b4f039d53035238fa0320fe00b ''Empirical formulae, page 38, Gateway GCSE Chemistry, Oxford, OCR '']

:[https://www.amazon.co.uk/gp/product/1782945695/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945695&linkCode=as2&tag=nrjc-21&linkId=ceafcc80bcad6b6754ee97a0c7ceea53 ''Empirical formulas, page 105, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR '']

:[https://www.amazon.co.uk/gp/product/1782945679/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945679&linkCode=as2&tag=nrjc-21&linkId=a2db42f7b4bdf10cafaafa3bb9120940 ''Empirical formulas, page 32, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR '']

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