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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: jonjon1324 on October 02, 2010, 07:36:18 PM

Title: Will Calcium hydroxie form?
Post by: jonjon1324 on October 02, 2010, 07:36:18 PM: I was asked if NH3 solution is mixed with 0.5 CaCl2, should Ca(OH)2 form? Make a prediction based on the fact that the pH of 1 M NH3 is about 11.6? The answer is that it SHOULDN'T form, but I have NO idea why...I know Nh3 is a weak base and CaCl2 is an acidic solution, but I don't understand how I can tell whether Ca(OH)2 can form or not..
Title: Re: Will Calcium hydroxie form?
Post by: ooosh on October 02, 2010, 10:29:47 PM: No,they will form a Complex Compound-Ca(NH3)₄Cl₂,which can dissolve in water .ZnCl2 and AgCl can also form Zn(NH3)₄Cl₂and Ag(NH3)₄Cl,,many elements can form complex compound.
Title: Re: Will Calcium hydroxie form?
Post by: Borek on October 03, 2010, 04:02:49 AM: Quote from: ooosh on October 02, 2010, 10:29:47 PM
No,they will form a Complex Compound-Ca(NH3)₄Cl₂,which can dissolve in water

No such complex.
Title: Re: Will Calcium hydroxie form?
Post by: Borek on October 03, 2010, 04:03:25 AM: Quote from: jonjon1324 on October 02, 2010, 07:36:18 PM
I was asked if NH3 solution is mixed with 0.5 CaCl2, should Ca(OH)2 form? Make a prediction based on the fact that the pH of 1 M NH3 is about 11.6? The answer is that it SHOULDN'T form, but I have NO idea why...I know Nh3 is a weak base and CaCl2 is an acidic solution, but I don't understand how I can tell whether Ca(OH)2 can form or not..

What is solubility product of Ca(OH)₂?
Title: Re: Will Calcium hydroxie form?
Post by: jonjon1324 on October 03, 2010, 03:15:26 PM: Quote from: Borek on October 03, 2010, 04:03:25 AM
Quote from: jonjon1324 on October 02, 2010, 07:36:18 PM
I was asked if NH3 solution is mixed with 0.5 CaCl2, should Ca(OH)2 form? Make a prediction based on the fact that the pH of 1 M NH3 is about 11.6? The answer is that it SHOULDN'T form, but I have NO idea why...I know Nh3 is a weak base and CaCl2 is an acidic solution, but I don't understand how I can tell whether Ca(OH)2 can form or not..

What is solubility product of Ca(OH)₂?

It is 3 x 10^-5
Title: Re: Will Calcium hydroxie form?
Post by: Borek on October 03, 2010, 03:23:58 PM: My book gives different value, but let's assume the one you listed is the proper one, that you are expected to use.

Do you see why solubility product of calcium hydroxide is relevant? Can you think of a way to use it to check if calcium hydroxide will precipitate?
Title: Re: Will Calcium hydroxie form?
Post by: ooosh on October 03, 2010, 11:42:28 PM: Quote from: Borek on October 03, 2010, 04:02:49 AM
Quote from: ooosh on October 02, 2010, 10:29:47 PM
No,they will form a Complex Compound-Ca(NH3)₄Cl₂,which can dissolve in water

No such complex.

sorry,CaCl2.8NH3,ok?
Title: Re: Will Calcium hydroxie form?
Post by: Borek on October 04, 2010, 05:54:43 AM: Quote from: ooosh on October 03, 2010, 11:42:28 PM
sorry,CaCl2.8NH3,ok?

No, this is an exotic compound that you will never see in water solution.