Difference between revisions of "Half Equation"
(→Examples) |
|||
| (3 intermediate revisions by 2 users not shown) | |||
| Line 12: | Line 12: | ||
===Examples=== | ===Examples=== | ||
{| border="1" style="border-collapse:collapse" | {| border="1" style="border-collapse:collapse" | ||
| − | | style="height:10px; width: | + | | style="height:10px; width:100px; text-align:center;" |[[Balanced Symbol Equation]] |
| style="height:10px; width:200px; text-align:center;" |'''2Li<sub>2</sub>O(l) → 4Li(l) + O<sub>2</sub>(g)''' | | style="height:10px; width:200px; text-align:center;" |'''2Li<sub>2</sub>O(l) → 4Li(l) + O<sub>2</sub>(g)''' | ||
| style="height:10px; width:200px; text-align:center;" |'''CuCl<sub>2</sub>(aq) → Cu(s) + Cl<sub>2</sub>(g)''' | | style="height:10px; width:200px; text-align:center;" |'''CuCl<sub>2</sub>(aq) → Cu(s) + Cl<sub>2</sub>(g)''' | ||
| style="height:10px; width:200px; text-align:center;" |'''2H<sub>2</sub>O(l) → 2H<sub>2</sub>(g) + O<sub>2</sub>(g)''' | | style="height:10px; width:200px; text-align:center;" |'''2H<sub>2</sub>O(l) → 2H<sub>2</sub>(g) + O<sub>2</sub>(g)''' | ||
|- | |- | ||
| − | | style="height:10px; width: | + | | style="height:10px; width:100px; text-align:center;" |'''Half Equation''' at [[cathode]] |
| style="height:10px; width:200px; text-align:center;" |Li<sup>+</sup> + e<sup>-</sup> → Li | | style="height:10px; width:200px; text-align:center;" |Li<sup>+</sup> + e<sup>-</sup> → Li | ||
| style="height:10px; width:200px; text-align:center;" |Cu<sup>+2</sup>(aq) + 2e<sup>-</sup> → Cu(s) | | style="height:10px; width:200px; text-align:center;" |Cu<sup>+2</sup>(aq) + 2e<sup>-</sup> → Cu(s) | ||
| style="height:10px; width:200px; text-align:center;" |2H<sup>+</sup>(aq) + 2e<sup>-</sup> → H<sub>2</sub>(g) | | style="height:10px; width:200px; text-align:center;" |2H<sup>+</sup>(aq) + 2e<sup>-</sup> → H<sub>2</sub>(g) | ||
|- | |- | ||
| − | | style="height:10px; width: | + | | style="height:10px; width:100px; text-align:center;" |'''Half Equation''' at [[anode]] |
| style="height:10px; width:200px; text-align:center;" |2O<sup>-2</sup> → O<sub>2</sub> + 4e<sup>-</sup> | | style="height:10px; width:200px; text-align:center;" |2O<sup>-2</sup> → O<sub>2</sub> + 4e<sup>-</sup> | ||
| style="height:10px; width:200px; text-align:center;" |2Cl<sup>-</sup>(aq) → Cl<sub>2</sub>(g) + 2e<sup>-</sup> | | style="height:10px; width:200px; text-align:center;" |2Cl<sup>-</sup>(aq) → Cl<sub>2</sub>(g) + 2e<sup>-</sup> | ||
| style="height:10px; width:200px; text-align:center;" |4OH<sup>-</sup> → 2H<sub>2</sub>O(l) + O<sub>2</sub>(g) + 4e<sup>-</sup> | | style="height:10px; width:200px; text-align:center;" |4OH<sup>-</sup> → 2H<sub>2</sub>O(l) + O<sub>2</sub>(g) + 4e<sup>-</sup> | ||
|} | |} | ||
| + | |||
| + | ===References=== | ||
| + | ====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 ''Half equations, pages 104, 289-91, 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 ''Half equations, pages 142-144, GCSE Combined Science Trilogy; Chemistry, CGP, 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 ''Half equations, pages 167-169, GCSE Chemistry, CGP, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Half equations, pages 206, 255-7, GCSE Combined Science Trilogy 1, Hodder, 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=9e29fad914244909903e5e93f8a01d150 ''Half equations, pages 59, 65, GCSE Chemistry; The Revision Guide, 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 ''Half-equations, pages 87, 104-105, 107, 108, 123, GCSE Chemistry; Third Edition, Oxford University Press, AQA ''] | ||
| + | |||
| + | ====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 ''Half equations, pages 110-112, GCSE Combined Science; The Revision Guide, CGP, 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 ''Half equations, pages 134, 135, GCSE Chemistry, CGP, 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 ''Half equations, pages 210, 225, 231, GCSE Combined Science, Pearson 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 ''Half equations, pages 48-50, GCSE Chemistry; The Revision Guide, CGP, 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 ''Half equations, pages 66, 81, 87, GCSE Chemistry, Pearson, Edexcel ''] | ||
| + | |||
| + | ====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 ''Half equations, pages 37, 47, 48, Gateway GCSE Chemistry; The Revision Guide, CGP, 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 ''Half equations, pages 94, 111, 124, Gateway GCSE Chemistry, Oxford, OCR ''] | ||
Latest revision as of 16:58, 11 December 2019
Contents
Key Stage 4
Meaning
A half equation is a type of symbol equation which shows how individual ions gain or lose electrons at an electrode during electrolysis.
About Half Equations
- In half equations only one ion is considered at a time, or the changes at one electrode.
- Half equations use the letter 'e' to represent electrons.
- Half equations can be taken from balanced symbol equations.
- The total charge on each side of a half equation must add to zero.
- The number of each element must be the same on both sides of a half equation.
Examples
| Balanced Symbol Equation | 2Li2O(l) → 4Li(l) + O2(g) | CuCl2(aq) → Cu(s) + Cl2(g) | 2H2O(l) → 2H2(g) + O2(g) |
| Half Equation at cathode | Li+ + e- → Li | Cu+2(aq) + 2e- → Cu(s) | 2H+(aq) + 2e- → H2(g) |
| Half Equation at anode | 2O-2 → O2 + 4e- | 2Cl-(aq) → Cl2(g) + 2e- | 4OH- → 2H2O(l) + O2(g) + 4e- |
References
AQA
- Half equations, pages 104, 289-91, GCSE Chemistry, Hodder, AQA
- Half equations, pages 142-144, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
- Half equations, pages 167-169, GCSE Chemistry, CGP, AQA
- Half equations, pages 206, 255-7, GCSE Combined Science Trilogy 1, Hodder, AQA
- Half equations, pages 59, 65, GCSE Chemistry; The Revision Guide, CGP, AQA
- Half-equations, pages 87, 104-105, 107, 108, 123, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Edexcel
- Half equations, pages 110-112, GCSE Combined Science; The Revision Guide, CGP, Edexcel
- Half equations, pages 134, 135, GCSE Chemistry, CGP, Edexcel
- Half equations, pages 210, 225, 231, GCSE Combined Science, Pearson Edexcel
- Half equations, pages 48-50, GCSE Chemistry; The Revision Guide, CGP, Edexcel
- Half equations, pages 66, 81, 87, GCSE Chemistry, Pearson, Edexcel