## hpfan101 one year ago Question about finding the limiting reactant. So far, I found the molar mass (g/mol) of each substance in this chemical reaction but I'm not sure what to do next. Phosphoric acid can be prepared by reaction of sulfuric acid with “phosphate rock” according to the equation: Ca3(PO4)2 + 3H2SO4  3CaSO4 + 2H3PO4 Suppose the reaction is carried out starting with 129 g of Ca3(PO4)2 and 97.4 g of H2SO4. Which substance is the limiting reactant? A) Ca3(PO4)2 B) H2SO4 C) CaSO4 D) H3PO4 E) none of these

1. Zale101

$$\bf{Step ~1}$$: Use the given grams for each of the reactants and convert to moles $$\bf{Step~ 2}$$: Use those mols of each reactants and convert to mols of Phosphoric acid (H3PO4). You use mole to mole ratios: For every 1 mole of reactant Ca3(PO4)2 , only 2 moles of H3PO4 is produced as products For every 3 moles of reactant 3H2SO4 , only 2 moles of H3PO4 is produced as products $$\bf{ Step ~3}$$: Compare which mols of 2H3PO4 is less. The less mols of the products indicates the reactants you started with was the limiting reactant.

2. hpfan101

Thank you!!

3. anonymous

actual yield / theoretical yield x 100 grams - moles - grams - moles

4. Zale101

No problem! :)