How many mL of 2.0M HCL are required to produce 45L of hydrogen at STP?

Question

I don't know how to approach this question.

Answer 1

ok here is the reaction

2HCl --> H2 + Cl2

at stp i think it's like 1 mol = 22.4L  ok yeah yeah.  if you don't believe me just use the ideal gas law and solve it for volume.  PV=nRT, you know.

ok so just use the factor label method.  all you need to know are the conversions:  1 mol = 22.4 L; 1000mL in 1L  and the mole ratio of HCl to H2 is 2:1.  and you know the molarity, 2.0M which is 2 mol of HCl per liter.

ok so we do this

45L H2 x 1 mol H2 x 2 mol HCl x  1L HCl   x 1000mLHCl

________22.4L H2__1 mol H2___2molHCl__1LHCl

those lines are just for spacing, and you should know that all those things where there's something over another thing, that's division, so it's really like 45L H2 x (1molH2/22.4LH2) x (2molHCl/1molH2) x (1LHCl/2molHCl) x (1000mL HCl/1L HCl)

just gotta cancel out all your units going from L H2 to mL HCl

ok i got around 2000mL but you should check it because i didn't use my regular calc so yeah..