Chem help please

Question

Gold metal can be dissolved using sodium cyanide according to the reaction below:

4 Au(s) + 8 NaCN (aq) + O₂(g) + 2 H₂O(l) → 4 NaAu(CN)₂(aq) + 4 NaOH(aq) 

 

If I added 86.7 g of Au to 750 mL of a 1.8 M solution of NaCN, which reagent would be limiting?

Type the reagent which is limiting (Au or NaCN or neither if there is no limiting reagent)

Answer 1

An easy way to determine the limiting reactant is to divide the moles of each reactant by the corresponding coefficient in the balanced equation. Whichever value is less will be the limiting reactant.

4 Au(s) + 8 NaCN (aq) + O₂(g) + 2 H₂O(l) → 4 NaAu(CN)₂(aq) + 4 NaOH(aq) 

For Au: 86.7 g x 1 mol / 197 g = 0.440 mol (÷4=0.11)

For NaCN: 0.75 L x 1.8 mol/L = 1.35 mol (÷8=0.17)

Limiting reactant is Au since 0.11 < 0.17