Question

CH4+Cl2->CH2Cl2+HCl.
If 6.00 g of CH4 are mixed with 6.00 g of CL2, how much HCl can be made? What is the percent yield if 2.5 g are recovered from the reaction in the lab?

Answer 1

Here is a site. A lot of reading but the essentials are here. The problem you posted is a limiting reagent problem. If you have trouble, reply with details about what you don't understand.
http://www.shodor.org/UNChem/basic/stoic/