In: Chemistry
Use the following balanced equation to answer each part below H3PO4+3NaOH--->Na3PO4+3H2O
If you start the reaction with 100. grams of each reactant, which
reactant is the limiting reactant, and how many grams of the excess
reactant are left over? What mass of sodium phosphate is
produced?
Part 1:
The limiting reactant is
Part 2:
How much of the excess reactant remains?
Part 3:
How many grams of sodium phosphate are produced in this reaction?
Part 1:
In order to determine the limiting reactant, calculate the theoretical yield ie amount of product formed by each reactant. The reactant that produces the least amount of product is the limiting reactant.
To determine the number of grams of Na3PO4 formed:
Theoretical yield = (grams reactant) x (mole of reactant/molar mass of reactant) x (mole ratio: product/reactant) x (molar mass of product/mole product)
Amount of Na3PO4 formed from 100 grams of NaOH
grams Na3PO4 = (100 g NaOH) x (1 mol NaOH/40.00 g NaOH) x (1 mol Na3PO4/3 mol NaOH) x (163.94 g Na3PO4/1 mol Na3PO4)
grams of Na3PO4 = 136.61 grams
Amount of Na3PO4 formed from 100 grams of H3PO4
grams Na3PO4 = (100 g H3PO4) x (1 mol H3PO4/98.00 grams H3PO4) x (1 mol Na3PO4/1 mol H3PO4) x (163.94 g Na3PO4/1 mol Na3PO4)
grams Na3PO4 = 167.28 grams
Since sodium NaOH formed less product than the H3PO4.This means the NaOH is the limiting reactant and 136.61 grams of sodium phosphate is formed.
To determine the amount of excess reactant remaining, the amount used is needed.
Part 2:
grams of reactant used = (grams of product formed) x (1 mol of product/molar mass of product) x (mole ratio of reactant/product) x (molar mass of reactant)
grams of H3PO4 used = (136.61 grams Na3PO4) x (1 mol Na3PO4/163.94 g Na3PO4) x (1 mol H3PO4/1 mol Na3PO4) x (98 g H3PO4/1 mol)
grams of H3PO4 used = 81.66 grams
This number can be used to determine the remaining amount of excess reactant.
Grams H3PO4 remaining = initial grams H3PO4 - grams H3PO4 used
grams H3PO4 remaining = 100 grams - 81.66 grams
grams H3PO4 remaining = 18.34 grams
ANSWER
When 100 grams of NaOH is reacted with 100 grams of H3PO4,
Part 3:
136.61 grams of Na3PO4 are formed in this reaction (see part
1)