Malvi Troubles (:

[malvi]

First question: Find the empirical formula for 15.8% Al, 28.1% S, 56.1% O. I know how to do it, but I keep getting the wrong answer. The answer is Al2S9O12.

[Uma Sharma]

Hi Malvi
calculate no of moles for each element and convert it to simplest ratio.I am sure till this point you must be correct .
Al =1
S = 1.5
O = 6
Now here S is 1.5 which is can neither be approximated as 1 nor as 2 so what we will do -multiply all numbers by 2 to get whole number.
Al =1 X2 = 2
S = 1.5 X2= 3
O = 6 X2= 12
In the quiz answer should be Al2S3O12
I hope you agree with the above formula .
I have edited the formula in the quiz also.
For the second wrong question which you attempted in AP quiz in  chemtopper courses
Convert mass of P4----moles of P4------moles of H3PO4 ------mass of H3PO4
whatever mass will come that is the theoretical yield
take ratio of actual with theoretical and multiply it by 100%
I am getting theoretical yield somewhere near 65 g
Just try once more .

[malvi]

What is the name for Fe2(CO3)3
I got it wrong on the quiz

And also, what is potassium trinitride? How is that K3N? Wouldn't it be KN3?

[malvi]

2nd one

[malvi]

3rd one

[Uma Sharma]

What is the name for Fe2(CO3)3
I got it wrong on the quiz

And also, what is potassium trinitride? How is that K3N? Wouldn't it be KN3?

Fe2(CO3)3----Iron(III)carbonate

Actually it should be Potassiumnitride
K3N

[Uma Sharma]

[quote author=malvi link=topic=251.msg349#msg349 date=1255659237]
3rd one
[/quote]

This is also based on Molarity
Molarity = no of moles / Volume in L