Acetylene is hydrogenated to form ethane. the feed to the reactor contains 1.4 mol h2/mol c2h2. (find properties of the reactants/products in appendix of book) a. determine the limiting reactant and calculate the percentage by which the other reactant is in excess.

The limiting reactant is H₂. C₂H₂ is in 43 % molar excess.

Step 1. Write the balanced chemical equation  

   C₂H₂ +2H₂ ⟶ C₂H₆

n:   1        1.4

Step 2. Identify the limiting reactant

Calculate the moles of C₂H₆ we can obtain from each reactant.  

From C₂H₂: Moles of C₂H₆ = 1 mol C₂H₂ × (1 mol C₂H₆/1 mol C₂H₂) = 1 mol C₂H₆

From H₂: Moles of S = 1.4 mol H₂ × (1 mol C₂H₆/2 mol H₂) = 0.7 mol C₂H₆

H₂ is the limiting reactant because it gives the smaller amount of C₂H₆.

Step 4. Calculate the molar excess of C₂H₂.

Theoretical moles of C₂H₂ reacted = 1.4 mol H₂ × (1 mol C₂H₂/2 mol H₂)

= 0.7 mol C₂H₂

Excess moles of C₂H₂ = (1 – 0.7) mol = 0.3 mol

% Molar excess = excess moles/theoretical moles × 100 % = 0.3/0.7 × 100 %

= 43 %

the answer for sodium is 0.186

the answer for rubidium is 0.251