When 7.76 grams of magnesium bicarbonate are mixed with 300. mL of 0.10 M hydrocyanic acid, how many liters of gas are evolved at STP?

Answer 1

Here is a worked example of a stoichiometry problem. Just follow the steps. After moles HCN are calculated, remember 1 mole of a gas occupies 22.4 L at STP.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

I am having trouble balancing this reaction!