# chemistry 11

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a chamber contains 5.5 grams of hydrogen gas another chamber contains chlorine when the valve is opened the react to form hydrogen chloride with a mass 1995.5 grams. What is the mass of chlorine?

• chemistry 11 -

moles HCl = 1995.5/molar mass HCl = ?
? moles HCl x molar mass HCl = grams HCl.
g HCl x (molar mass Cl2/2*molar mass HCl)= grams Cl2.

• chemistry 11 -

i don't really understand could you do it again pls and thanks. it was 199.5 my bad

• chemistry 11 -

for total mass

• chemistry 11 -

H2 + Cl2 ==> 2HCl
5.5..........199.5g

The first post was the short way; however, I put an extra step that is not needed (but it didn't change the answer) and that may be what confused you. Here is a better way.
moles HCl produced = grams/molar mass = 199.5/36.5 = about 5.5 (but you do it more accurately).
Now use the coefficients in the balanced equation to convert moles HCl to moles Cl2.
5.5 moles HCl x (1 mol Cl2/2moles HCl) = 5.5 x (1/2) = 2.75 moles Cl2.
grams Cl2 = moles Cl2 x molar mass Cl2 = about 195 grams. Interesting.