Posted by Joseph on .
When a 1.350g sample of element X is heated in a stream of chlorine gas 6.67g of XCl3 are formed.1.) What(write) is a balance equation for the reaction using 'X' for the element? 2.) Calculate the atomic weight of X. 3.)What mass of X is left unreacted? 4.)When 1.00 grams of X react with excess Cl2 4.27 grams of XCL3 are formed.What is the % yield for this experiment?

Chemistry 
DrBob222,
2X + 3Cl2 ==> 2XCl3
1.350..y......6.67
mass Cl2 combined must be 6.671.35 = 5.29g
Then I would convert grams to moles. moles = grams/molar mass.
Cl2 = 5.29/35.44 = 0.1501
X = 1.350/molarmass = ??
If the formula in the problem is given as XCl3, we know then that ??moles x must be 0.15/3 = 0.05
Now, 1.35/molar mass = 0.05 and solve for molar mass. I get 26.97 but I've estimated here and there and you should do it more accurately. For the last part, 1.00 g X = 1.00/26.98 = 0.0371. Convert to moles XCl3 and that will be 0.0371 x (2 moles XCl3/2 moles X) = 0.0371 moles XCl3. Now convert to grams.
g = moles x molar mass = 0.0371 x 133.34 = 4.94 g.This is the theoretical yield.
%yield = (actual yield/theoretical yield)*100 = ??