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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: User1234 on August 11, 2009, 12:15:47 AM

Title: Why Calcium Hydroxide must be prepared early?
Post by: User1234 on August 11, 2009, 12:15:47 AM

In a experiment to determine the solubility product of sodium hydroxide, one of the first few procedure is to prepare Calcium Hydroxide early.
The prepared solution is then transferred to mix with hydrocloric acid with burette.
I'm wondering why the solution must be prepared early.

Thanks for any reply.

Title: Re: Why Calcium Hydroxide must be prepared early?
Post by: Johnny010 on August 20, 2009, 07:26:43 AM

Most likely to ensure the Calcium hydroxide has been properly formed?
How was it prepared?

Title: Re: Why Calcium Hydroxide must be prepared early?
Post by: renge ishyo on August 20, 2009, 02:55:29 PM

If he means why must calcium hydroxide be prepared "fresh" on the day you perform your experiment as opposed to letting it sit around in a bottle for awhile like HCl then the reason for that is that it will react with carbon dioxide in the atmosphere if it is exposed to it for a short period of time (it can form calcium carbonate, bicarbonate ion, etc.). If you leave a bottle of a "hydroxide base" open overnight you have to toss it the next day and make a new batch. I don't know what he means by preparing it "early" though, so I may be misunderstanding the question.