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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: lacoste on August 03, 2008, 09:25:02 pm

Title: chem qst..
Post by: lacoste on August 03, 2008, 09:25:02 pm
Calculate the molarity of CaCl2 in 25mL of 0.40M CaCl2 added to 50mL of 1.2M CaCl2?

cheers.
Title: Re: chem qst..
Post by: Collin Li on August 03, 2008, 09:28:33 pm
This is a quite basic question. If you couldn't get the right answer, the common traps are:

* Molarity is a unit for concentration (moles per litre), so you are finding the concentration
* Remember to use the final volume as the sum of the two volumes you added together
* There is no reaction happening! Some teachers always say "write down the equation first," but sometimes there is simply no reaction. Visualise the process, and you will realise it's just a simple mixing of two solutions of the same thing. This results in... the same thing (different concentration possibly though).

Solution



Title: Re: chem qst..
Post by: lacoste on August 03, 2008, 09:30:57 pm
thank-you for the quick reply !!

genius!

hope u dont mind more qsts coming..
Title: Re: chem qst..
Post by: Collin Li on August 03, 2008, 09:33:06 pm
Quote from: lacoste on August 03, 2008, 09:30:57 pm
thank-you for the quick reply !!

genius!

hope u dont mind more qsts coming..

No problem. Nope, I don't mind. I just edited in some comments above, just to sort of commentate my thoughts on the question.
Title: Re: chem qst..
Post by: lacoste on August 03, 2008, 09:35:36 pm
12). Calculate the molaar concentration present in the following solutions:
a). 1.55L of solution, which contains 1.223g of CaCl2?

d). 20.0 L of solution, containing 4.07x10^-3 mol of KF
Title: Re: chem qst..
Post by: lacoste on August 03, 2008, 09:37:43 pm
yeh i think they are basic qsts but i missed a few lessons of chem at school
Title: Re: chem qst..
Post by: /0 on August 03, 2008, 09:49:40 pm
12.
a)

d)