posted by Dana on .
Magnesium reacts with HCl to produce magnesium chloride and hydrogen gas.
What is the molarity of the HCl solution if 330 ml of the HCl solution reacts with magnesium to produce 7.40 L of H2 gas measured at STP?
7.40 L H2 gas @ STP = 7.40/22.4 = moles H2 @ STP.
moles HCl = moles H2 x (2 moles HCl/1 mole H2) = ??moles H2 x 2 = xx moles HCl
Then M HCl = mols HCl/L HCl
You have moles and L, solve for M.