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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: jbpoon on June 02, 2012, 03:53:48 PM

Title: How do i know which one is solid and aqueous?
Post by: jbpoon on June 02, 2012, 03:53:48 PM
(http://water.me.vccs.edu/courses/env110/clipart/floc_calc.gif)

I know you can look at the solubility rules. According to the solubility rules, Al2(SO4)3 is aqueous, Ca(OH)2 is solid, Al(OH)3 is solid and CaSO4 is solid.

is it even possible to form two precipitate from one reaction...? I'm confused..
Title: Re: How do i know which one is solid and aqueous?
Post by: Borek on June 02, 2012, 05:53:51 PM
Quote from: jbpoon on June 02, 2012, 03:53:48 PM
is it even possible to form two precipitate from one reaction...?

Yes.

Al(OH)3 is tricky. In neutral solutions it will precipitate, but it is soluble both in low and high pH due to aluminum amphoterism.

Note you can easily format reactions on the forum, no need to post images:

Al2(SO4)3 + 3Ca(OH)2  :rarrow: 2Al(OH)3 + 3CaSO4
Title: Re: How do i know which one is solid and aqueous?
Post by: Arkcon on June 02, 2012, 06:03:08 PM
Also, solubility lists (not the rules) will tell you that Ca(OH)2 is slightly soluble in water.  So that's another little trick to the question.
Title: Re: How do i know which one is solid and aqueous?
Post by: AWK on June 02, 2012, 11:27:19 PM
solubility of CaSO4 is around 2 g/Liter, Ca(OH)2 about 1 to 1.5 g/Liter. Hence using saturated lime solution you should calculate the possibility of CaSO4 precipitation.
Title: Re: How do i know which one is solid and aqueous?
Post by: jbpoon on June 02, 2012, 11:30:55 PM
Quote from: AWK on June 02, 2012, 11:27:19 PM
solubility of CaSO4 is around 2 g/Liter, Ca(OH)2 about 1 to 1.5 g/Liter. Hence using saturated lime solution you should calculate the possibility of CaSO4 precipitation.
how do i calculate the possibility of the precipitation..?
Title: Re: How do i know which one is solid and aqueous?
Post by: Borek on June 03, 2012, 04:42:18 AM
Quote from: jbpoon on June 02, 2012, 11:30:55 PM
how do i calculate the possibility of the precipitation..?

You can calculate the equilibrium using solubility products. Quite possible it is well above your head and you don't have to care about it yet.

It really depends on how advanced you are with your chemistry education.
Title: Re: How do i know which one is solid and aqueous?
Post by: jbpoon on June 03, 2012, 02:08:21 PM
Quote from: Borek on June 03, 2012, 04:42:18 AM
Quote from: jbpoon on June 02, 2012, 11:30:55 PM
how do i calculate the possibility of the precipitation..?

You can calculate the equilibrium using solubility products. Quite possible it is well above your head and you don't have to care about it yet.

It really depends on how advanced you are with your chemistry education.
i'm in grade 11 chemistry. i'm over-thinking this; i'm just going to work with what i know and show my solution(what i thought in the OP) to the teacher and clear out any confusion. Thanks guys.