lime water

Lime water is used as the common laboratory test for carbon dioxide, state the name or formula of the chemical that is dissolved in water to make lime water.

I wrote calcium oxide but it's not in the mark scheme, only calcium hydroxide is. Why isn't it in the mark scheme?

Reply 1

Dynamo123

7

That would be a question for the examiners to answer. I guess we should move beyond inert mark schemes now.

Reply 2

advice_guru

Calcium oxide and calcium hydroxide are different?

Reply 3

natninja

21

Original post by advice_guru

Calcium oxide and calcium hydroxide are different?

Original post by tazmaniac97

Lime water is used as the common laboratory test for carbon dioxide, state the name or formula of the chemical that is dissolved in water to make lime water.

I wrote calcium oxide but it's not in the mark scheme, only calcium hydroxide is. Why isn't it in the mark scheme?

Calcium Oxide: CaO This has a violent reaction with water....

Calcium Hydroxide: Ca(OH)2 (which reacts with excess CO2 to form calcium carbonate and water)

(edited 10 years ago)

Reply 4

Magzter

4

Limewater by definition: Limewater is the common name for a saturated solution of calcium hydroxide

CaO doesnt dissolve in water but react with it:

CaO (s) + H₂O (l)

Ca(OH)₂

Reply 5

tazmaniac97

OP

12

Original post by natninja

Calcium Oxide: CaO This has a violent reaction with water....

Calcium Hydroxide: Ca(OH)2 (which reacts with excess CO2 to form calcium carbonate and water)

Original post by Magzter

Limewater by definition: Limewater is the common name for a saturated solution of calcium hydroxide

CaO doesnt dissolve in water but react with it:

CaO (s) + H₂O (l)

Ca(OH)₂

Oh I see, thanks :smile: