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Borax with hot water in supersaturated solution makes crystals. what is the ionic...

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sammieg | Student, Undergraduate | eNotes Newbie

Posted July 31, 2012 at 5:25 PM via web

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Borax with hot water in supersaturated solution makes crystals. what is the ionic equation for it ?

i understand thats because hot water can contain more borax and on cooling the borax molecules crystallise out. BUT why does it specifically crystallise, instead of the powder just getting deposited out ??

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chaobas | College Teacher | (Level 1) Valedictorian

Posted July 31, 2012 at 9:24 PM (Answer #1)

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Borax is Na2B4O7(sodium borate). When dissolved in water, it formed hydrated compound whhich is crystallline in nature.

The formula of the hydrated compound is Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O

Na2B4O7 + H2O ====> Na2[B4O5(OH)4]*8H2O

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sanjeetmanna | College Teacher | (Level 3) Assistant Educator

Posted August 16, 2012 at 4:36 AM (Answer #2)

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Borax is a solid, odorless, powder with colorless crystalline in nature also known as sodium borate formed from boric acid, its a ionic crystalline salt by nature. When disolved in water forms alkaline solution, hot water can hold more borax than cold water.

Borax when mixed completely in hot water and when it reaches its saturation point it cannot hold borax anymore this is called supersaturation. Later when it is cooled borax is released out in its natural crystal form just like sugar crystals.

Borax with water forms

Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O this formula difference depending on the water content.

When it is dissolved in water it will dissociate as

Na2[B4O5(OH)4]·8H2O (s) → 2 Na+ (aq) + B4O5(OH)42– (aq) + 8 H2O (l)

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