if you are looking to do mass to mass conversions...?

Question

when doing mass to mass conversions of different elements/compunds how would you set it up to get the answer?

since i guess i was not specific enough.. here are some examples of what I mean...

1. CH4 + 3Cl2 -------> CHCl3 + 3HCl
How many grams of CH4 is needed to produce 50.0 g CHCl3?

Answer 1

According to the additional statement. I will just solve it.
1 mol of CH4 is required to produce 1 mol of CHCl3
no= mass/molarmass
no of mols of CHCl= 50/12+1+35.5*3
no of mols of CHCl= 0.4184 mols
there fore 0.4184 mols of CH4 would be required
mass of CH4= molar mass * no of mols
mass of CH4 = 0.4184* (12+4*1)
Mass of CH4 = 6.6944

Answer 2

I'm not sure I understand your question completely, but I'm guessing you're talking about stoichiometry problems. So, if you have a reaction, and you begin with a set number of grams of one substance, you're after how many grams of a different one are required or will be produced, right?

In all cases like this, you need to have a balanced chemical equation for the reaction. Then, you use the atomic/molecular weight of the substance you are beginning with to convert the mass into moles. Then you use the coefficients in the balanced equation to convert moles of one substance to moles of another. Finally, you use the atomic/molecular weight of the second substance to convert back to grams.

Hope this helps...