Answer to Question #74328 in General Chemistry for Essence

Question

How many grams of H2 will be produced from when 36 grams of HCI is allowed to react?

Answer 1

It is not clear with what substance HCL is allowed to react. However, from the common knowledge H2 will be formed upon reaction of HCl with metals, for example Mg in this case:
Mg(s) + 2 HCl(aq) --> MgCl 2(aq) + H 2(g)
Calculate number of moles of HCl: 36 g/36.5 g/mole =0.99 moles HCl
According to the stoichiometry of the reaction number of moles of produced H2: 0.99 moles/2 = 0.49 moles, corresponds to grams oh H2 = 0.49 moles x 2 g/moles = 0.99 g H2
Note: the answer will be different if the metal reaction has different oxidation state. One need to write a balanced equation for each specific reaction