A ==Key Stage 3=====Meaning===An [[chemicalalkali]] is a [[Metal Hydroxide]] [[solution]] that has a [[pH]] more than [[neutralNeutral (Chemistry)|7]]. : [[Noun]]: '''Alkali''': [[Adjective]]: '''Alkaline''' ===About Alkalis===: [[Alkali]]s can be an [[Irritant]], [[Harmful]] or [[Corrosive]] and should be handled with care.: [[Alkali]]s can be used to [[Neutralisation|neutralise]] [[acid]]s.: [[Alkali]]s can be [[concentrated]] or [[dilute]].: [[Alkali]]s can be weak or strong which depends on the type of [[alkali]].: [[Alkali]]s turn [[Litmus]] paper blue.: [[Alkali]]s turn [[Universal Indicator]] blue, indigo and purple depending on the strength of the [[alkali]].Some common [[Alkali]]s you should know:*[[Sodium Hydroxide]]*[[Potassium Hydroxide]] ==Key Stage 4=====Meaning===An [[alkali]] is [[base|basic]] [[compound]] which [[dissolve]]s in [[water]] to form [[Hydroxide Ion (Chemistry)|OH<sup>-</sup> ions]] making a [[solution]] with [[pH]] greater than [[Neutral (Chemistry)|7]] that . ===About Alkalis===: [[Alkali]]s are [[base]]s in [[solution]] which form [[Hydroxide Ion (Chemistry)|Hydroxide ions]].: When a [[base]]ic [[compound]] [[dissolve]]s in [[water]] a [[Hydroxide Ion (Chemistry)|Hydroxide ion]] becomes dissociated from either the [[base|basic]] [[compound]] or from a [[water]] [[molecule]]. That [[Hydroxide Ion (Chemistry)|Hydroxide ion]] is free to move separately in the [[solution]].: The [[Hydroxide Ion (Chemistry)|Hydroxide ion]]s in an [[alkali]] will donate [[electron]]s to [[Hydrogen Ion (Chemistry)|Hydrogen ions]] to form [[water]]. This is a [[neutralisation]] [[Chemical Reaction|reaction]].: The strength of an [[alkali]] is measured on the [[pH]] scale. The more [[dissolvedHydroxide Ion (Chemistry)|Hydroxide ions]] in a [[solution]] the lower the [[pH]]. ===Examples===[[Metal Hydroxide]]s form '''Hydroxide ions''' in [[water]].: NaOH(aq) → Na<sup>+</sup>(aq)+OH<sup>-</sup>(aq): KOH(aq) → K<sup>+</sup>(aq)+OH<sup>-</sup>(aq): Mg(OH)<sub>2</sub>(aq) → Mg<sup>+2</sup>(aq)+2OH<sup>-</sup>(aq): Ca(OH)<sub>2</sub>(aq) → Ca<sup>+2</sup>(aq)+2OH<sup>-</sup>(aq): Al(OH)<sub>3</sub>(aq) → Al<sup>+3</sup>(aq)+3OH<sup>-</sup>(aq) [[Metal Oxide]]s [[Chemical Reaction|react]] with [[water]] to [[product|produce]] [[Metal Hydroxides]] which also form '''Hydroxide ions'''.: Na<sub>2</sub>O(s) + H<sub>2</sub>O(l) → 2Na<sup>+</sup>(aq)+2OH<sup>-</sup>(aq): K<sub>2</sub>O(s) + H<sub>2</sub>O(l) → 2K<sup>+</sup>(aq)+2OH<sup>-</sup>(aq): MgO(s) + 2H<sub>2</sub>O(l) → Mg<sup>+2</sup>(aq)+2OH<sup>-</sup>(aq): CaO(s) + 2H<sub>2</sub>O(l) → Ca<sup>+2</sup>(aq)+2OH<sup>-</sup>(aq): Al<sub>2</sub>O<sub>3</sub>(s) + 3H<sub>2</sub>O(l) → 2Al<sup>+3</sup>(aq)+6OH<sup>-</sup>(aq) [[Ammonia]] also [[Chemical Reaction|reacts]] with [[water]] to produce '''Hydroxide ions''':: NH<sub>3</sub>O(aq) + H<sub>2</sub>O(l) ⇌ NH<sub>4</sub><sup>+</sup>(aq)+OH<sup>-</sup>(aq) ===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 ''Alkali, pages 142-3, 148, 150, GCSE Chemistry; Student Book, Collins, AQA'']:[https://www.amazon.co.uk/gp/product/1782945598/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945598&linkCode=as2&tag=nrjc-21&linkId=ad276ad49df77ab4b40ab4fd0fe09665 ''Alkalis, page 128, GCSE Combined Science; The Revision Guide, CGP, 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 ''Alkalis, pages 107, 112, 280, 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 ''Alkalis, pages 124-126, 130, 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 ''Alkalis, pages 146-151, 155, 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 ''Alkalis, pages 209, 247, 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=9e29fad914244909903e5e93f8a01d36 ''Alkalis, pages 51, 52, 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 ''Alkalis, pages 74-77, 92, 94, 96-97, 163, GCSE Chemistry; Third Edition, Oxford University Press, 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 ''Alkalis; reaction with acids, pages 249, 252-3, GCSE Combined Science Trilogy 1, Hodder, 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 ''Alkalis, page 118, 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 ''Alkalis, page 43, 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 ''Alkalis, pages 105, 109, GCSE Combined Science; The Revision Guide, 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 ''Alkalis, pages 196-197, 204-205, 208-209, 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 ''Alkalis, pages 52-53, 60-61, 64-65, 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 ''Alkalis; reactions of, pages 185, 186, 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 ''Alkalis; reactions of, pages 47, 65, GCSE Chemistry; The Revision Guide, CGP, Edexcel ''] ====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 ''Alkalis, pages 112, 114, Gateway GCSE Combined Science; 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 ''Alkalis, pages 112-115, 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 ''Alkalis, pages 43, 45, 64, GCSE Chemistry; The Revision Guide, CGP, OCR Gateway '']