# Need Help!!! Molar Mass calculations

While Writing a Mock exam, I stumbled upon a molar mass calculation which i couldn't answer

"Each tablet contains the same number of moles of CaCO and MgCO. One tablet reacted with excess hydrochloric acid to produce 0.24dm^3 of carbon dioxide at r.t.p

(i) Calculate how many moles of CaCO there are in one tablet

Number of moles CO2 =

Number of moles of CaCO3 and MgCO3 =

Number of moles of CaCO3 =

Any help would be much appreciated.

Posted Tue 25th September, 2012 @ 08:17 by Jason Taylor

You just add up the mass number for each of the compounds and put the unit grams on the end. So for CO2 there would by 12+(16x2) = 44g

(Basically you just work out the Mr - relative formula mass - and it's in grams.)

I think that's right - hope it helps!

Answered Tue 25th September, 2012 @ 16:43 by Joanne

moles are easy when you understand them but sadly i didnt

Answered Tue 25th September, 2012 @ 16:44 by Connah Greenhalgh - Team GR

Number of moles CO2 =0.24/24=0.01 mol.

Number of moles of CaCO3 and MgCO3 =   mole ratio CaCO3:CO2 is 1:1 =2(0.01)=0.02 mol

Number of moles of CaCO3 = 0.02/2=0.01 mol.

Hope this helps.

Answered Mon 1st October, 2012 @ 17:42 by blue