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==Key Stage 4==
===Meaning===
===About Yield===
: The theoretical '''yield''' of [[product]] from a [[Chemical Reaction|chemical reaction]] can be calculated using the [[Balanced Symbol Equation|balanced symbol equation]] and the [[Relative Formula Mass|relative formula masses]] of all the [[molecule]]s involved.
: The experimental '''yield''' from a [[Chemical Reaction|chemical reaction]] is often not as large as the theoretical '''yield''' because not all of the [[reactant]]s will [[Chemical Reaction|react]]. This experimental '''yield''' is often expressed as a [[percentage]] of the theoretical '''yield''' and is known as the [[Percentage Yield]].
===Examples===
{| class="wikitable"
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Calculate the '''yield''' of [[Magnesium Oxide]] given 48g of [[Magnesium]] and excess [[Oxygen]].
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Find the '''yield''' of [[Water]] when 320g of [[Methane]] [[Chemical reaction|reacts]] with excess [[Oxygen]].
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Find the '''yield''' of [[Sodium Chloride]] when 7.3 of [[Hydrochloric Acid]] [[Chemical Reaction|reacts]] with excess [[Sodium Hydroxide]].
|-
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'''Write the Balanced Symbol Equation'''
2Mg + O<sub>2</sub> → 2MgO
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'''Write the Balanced Symbol Equation'''
CH<sub>4</sub> + 2O<sub>2</sub> → 2H<sub>2</sub>O + CO<sub>2</sub>
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'''Write the Balanced Symbol Equation'''
NaOH + HCl → NaCl + H<sub>2</sub>O
|-
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'''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].'''
M<sub>r</sub> of Mg = 24g
M<sub>r</sub> of MgO = 40g
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'''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].'''
M<sub>r</sub> of CH<sub>4</sub> = 16g
M<sub>r</sub> of H<sub>2</sub>O = 18g
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'''Find the [[Relative Formula Mass]] of the relevant [[reactant]]s and [[product]].'''
M<sub>r</sub> of NaOH = 40g
M<sub>r</sub> of HCl = 36.5g
M<sub>r</sub> of NaCl = 58.5g
|-
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'''State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
2 [[mole]]s of Mg are needed for every 2 [[mole]]s of MgO
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'''State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
1 [[mole]] of CH<sub>4</sub> is needed for every 2 [[mole]]s H<sub>2</sub>O
| style="height:20px; width:300px; text-align:left;" |
'''State the [[ratio]] of [[mole]]s of each [[chemical]] needed.'''
1 [[mole]] of HCl and NaOH are needed for every 1 [[mole]] of NaCl
|-
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'''Find the number of [[mole]]s supplied of the known [[mass]].'''
No. [[Mole]]s = <math>\frac{Mass}{M_r}</math>
No. [[Mole]]s = <math>\frac{48}{24}</math>
No. [[Mole]]s = 2 mol
Therefore 2 [[mole]]s of MgO is produced.
2 [[mole]]s of MgO = 40x2
'''Yield''' = 80g
| style="height:20px; width:300px; text-align:left;" |
'''Find the number of [[mole]]s supplied of the known [[mass]].'''
No. [[Mole]]s = <math>\frac{Mass}{M_r}</math>
No. [[Mole]]s = <math>\frac{320}{16}</math>
No. [[Mole]]s = 20 mol
Therefore 40 [[mole]]s of H<sub>2</sub>O are produced.
40 [[mole]]s of CO<sub>2</sub> = 18x40
'''Yield''' = 720g
| style="height:20px; width:300px; text-align:left;" |
'''Find the number of [[mole]]s supplied of the known [[mass]].'''
No. [[Mole]]s = <math>\frac{Mass}{M_r}</math>
No. [[Mole]]s = <math>\frac{7.3}{36.5}</math>
No. [[Mole]]s = 0.2 mol
Therefore 0.2 [[mole]] of [[Sodium Chloride]] is produced.
0.2 [[mole]] of NaCl = 11.7g
'''Yield''' = 11.7g
|}
===References===
====AQA====
:[https://www.amazon.co.uk/gp/product/0008158754/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0008158754&linkCode=as2&tag=nrjc-21&linkId=27ad53b0283feeff7fc5ae04a9e205f621 ''Yield, page 66-7, GCSE Biology; Student Book, Collins, AQA '']
:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Yield, page 78, GCSE Chemistry, Hodder, AQA '']
:[https://www.amazon.co.uk/gp/product/178294639X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294639X&linkCode=as2&tag=nrjc-21&linkId=51599bb45a2bfaf7c1b6a978b2ca2616 ''Yield, pages 184-186, GCSE Combined Science Trilogy; Chemistry, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/0198359381/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359381&linkCode=as2&tag=nrjc-21&linkId=47c8d1ae58d8b3a5e2094cd447154558 ''Yield, pages 68-71, GCSE Chemistry; Third Edition, Oxford University Press, 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 ''Yield, pages 97, 216-219, 317, 323, GCSE Chemistry; Student Book, Collins, AQA '']
:[https://www.amazon.co.uk/gp/product/1782945962/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945962&linkCode=as2&tag=nrjc-21&linkId=476bb5c8d1dfb5c08ac81b6d4d1c98d8 ''Yields, pages 141, 144, 216-218, GCSE Chemistry, CGP, AQA '']
:[https://www.amazon.co.uk/gp/product/1782945571/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945571&linkCode=as2&tag=nrjc-21&linkId=9e29fad914244909903e5e93f8a01d272 ''Yields, pages 45, 49, GCSE Chemistry; The Revision Guide, CGP, AQA '']
====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 ''Yields, pages 172-174, 189-191, 201-203, 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 ''Yields, pages 66, 68, GCSE Chemistry; 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 ''Yield, pages 158-161, 190, 200-203, 205, Gateway GCSE Chemistry, Oxford, 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 ''Yield, pages 66, 74, 80, 82, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR '']
:[https://www.amazon.co.uk/gp/product/1782945660/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945660&linkCode=as2&tag=nrjc-21&linkId=83aa4500ad7759e7f401a1c5ba5df758 ''Yields (in agriculture), pages 86, 87, Gateway GCSE Biology; The Revision Guide, CGP, OCR '']