In the reaction

Al2S3(s) + 6HCl(aq) --> 2AlCl3(aq) + 3H2S(g),
how many moles of HCl are used for each mole of AlCl3 formed?
A.0
B.2
C.3
D.1
E.1.5
where do you start and how do you figure it out?

urmom

The answer is 3

If you don't know why are you guessing?

Its C. 3 moles

Cheese

I would say...hmmm...A or C...I’m not really sure

Well, you start by looking at the equation and using common sense. Don't panic just because this is chemistry.

The coefficients in the balanced equation tell you that 6 mols HCl produce 2 molls AlCl3. So if you only wanted 1 mol AlCl3, how many mols of HCl would be required?

What if we did this in hamburgers instead of AlCl3 and HCl.
2 buns + 2 pieces of meat + 4 pickles ==> 2 hamburgers. So how many buns are needed to make 1 hamburger? 1
How many pieces of meat? 1
How many pickles? 2

Or, if you don't like hamburgers, use cars. If it takes you 1 hour to drive 60 miles, how long will it take to drive 30 miles? 1/2 an hour.