Consider this reaction:
3 K2CO3 (aq) + 2 CrCl3 (aq) -> Cr2(CO3)3 (s) + 6 KCl (aq)
If 1.2 moles of CrCl3 react, how many moles of K2CO3 will react with it?
A. 0.80 mol K2CO3
B. 1.2 mol K2CO3
C. 1.8 mol K2CO3
D. 2.4 mol K2CO3
I'm not sure where to even begin, I know how to find the mass and do percentages, but I am completely baffled. Any tips are most appreciated!
It is very very simple. You can convert mols of anything in an equation to mols of anything else in the equation by using the coefficients in the balanced equation. That's why you write and equation for almost everything you do and balance it. So you have 1.2 mols CrCl3 and you want to convert that to mols K2CO3.
1.2 mols CrCl3 x (3 mols K2CO3/2 mols CrCl3) = 1.2 x 3/2 = ?
How do you know which number goes on top and which on bottom? This is just like a dimensional analysis problem. You will notice the mols CrCl3 cancel with mols so you put the CrCl3 coefficient on the bottom. You want the units to come out in mols K2CO3 so you put that coefficient number on top.
Hope this helps.
See how easy it is? 1.2 mols CrCl3 x 1/2 converts to Cr2(CO3)3 and x 6/2 converts to KCl.
Thank you very much! I over analyzed it and made the problem harder than it was. That makes complete sense. Thank you for your speedy reply!
To determine how many moles of K2CO3 will react with 1.2 moles of CrCl3, we need to refer to the balanced chemical equation:
3 K2CO3 (aq) + 2 CrCl3 (aq) -> Cr2(CO3)3 (s) + 6 KCl (aq)
From the balanced equation, we can see that the ratio between K2CO3 and CrCl3 is 3:2. This means that for every 2 moles of CrCl3, 3 moles of K2CO3 will react.
To calculate the number of moles of K2CO3 that will react with 1.2 moles of CrCl3, we can use this ratio:
1.2 moles CrCl3 * (3 moles K2CO3 / 2 moles CrCl3) = 1.8 moles K2CO3
Therefore, the answer is C. 1.8 mol K2CO3.