a Balance this equation and state which of the six types of

,a) Balance this equation and state which of the six types of reaction is taking place: Type of ractioninals Displacement b) If I start this reaction with 40 grams of magnesium and an excess of nitric acid, how many grams of hydrogen gas will I produce? c) If 1.7 grams of hydrogen is actually produced, what was my percent yield of hydrogen?

Solution

b)

moles = mass / molar mass

moles of Mg = 40 g / (24.305 g/mol) = 1.64575 mol

now

consider the balanced reaction

Mg + 2 HNO3 ---> Mg(NO3)2 + H2

now

moles of H2 that can be produced = 1.64575 mol Mg x (1 mol H2 /1 mol Mg)

moles of H2 that can be produced = 1.64575 mol H2

now

mass of H2 that can be produced = 1.64575 mol H2 x 2 g/ mol

mass of H2 that can be produced = 3.29 g

c)

now

% yield = actual x 100/ theoretical

% yield = 1.7 g x 100 / 3.29 g

% yield = 51.65 %