Difference between revisions of "Alkali"
| Line 19: | Line 19: | ||
==Key Stage 4== | ==Key Stage 4== | ||
===Meaning=== | ===Meaning=== | ||
| − | An [[alkali]] is [[base|basic]] [[compound]] which [[dissolve]]s in [[water]] to form [[Hydroxide Ion|OH<sup>-</sup> ions]] making a [[solution]] with [[pH]] greater than [[Neutral (Chemistry)|7]]. | + | 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]]. |
===About Alkalis=== | ===About Alkalis=== | ||
| − | : [[Alkali]]s are [[base]]s in [[solution]] which form [[Hydroxide Ion|Hydroxide ions]]. | + | : [[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|Hydroxide ion]] becomes dissociated from either the [[base|basic]] [[compound]] or from a [[water]] [[molecule]]. That [[Hydroxide Ion|Hydroxide ion]] is free to move separately in the [[solution]]. | + | : 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|Hydroxide ion]]s in an [[alkali]] will donate [[electron]]s to [[Hydrogen Ion|Hydrogen ions]] to form [[water]]. This is a [[neutralisation]] [[Chemical Reaction|reaction]]. | + | : 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 [[Hydroxide Ion|Hydroxide ions]] in a [[solution]] the lower the [[pH]]. | + | : The strength of an [[alkali]] is measured on the [[pH]] scale. The more [[Hydroxide Ion (Chemistry)|Hydroxide ions]] in a [[solution]] the lower the [[pH]]. |
Revision as of 13:26, 4 January 2019
Key Stage 3
Meaning
An alkali is a Metal Hydroxide solution that has a pH more than 7.
About Alkalis
- Alkalis can be an Irritant, Harmful or Corrosive and should be handled with care.
- Alkalis can be used to neutralise acids.
- Alkalis can be concentrated or dilute.
- Alkalis can be weak or strong which depends on the type of alkali and the concentration.
- Alkalis turn Litmus paper blue.
- Alkalis turn Universal Indicator blue, indigo and purple depending on the strength of the alkali.
Some common Alkalis you should know:
Key Stage 4
Meaning
An alkali is basic compound which dissolves in water to form OH- ions making a solution with pH greater than 7.
About Alkalis
- Alkalis are bases in solution which form Hydroxide ions.
- When a baseic compound dissolves in water a Hydroxide ion becomes dissociated from either the basic compound or from a water molecule. That Hydroxide ion is free to move separately in the solution.
- The Hydroxide ions in an alkali will donate electrons to Hydrogen ions to form water. This is a neutralisation reaction.
- The strength of an alkali is measured on the pH scale. The more Hydroxide ions in a solution the lower the pH.