A traditional analysis for samples containing calcium ion was to precipitate the calcium ion with sodium oxalate ( Na 2 C 2 O 2 ) solution and then to collect and weigh either the calcium oxalate itself or the calcium oxide produced by heating the oxalate precipitate:

:math> Ca 2 + ( a q ) + C 2 O 4 2 − ( a q ) → CaC 2 O 4 ( s )

ppose a sample contained 0.1014 g of calcium ion. What theoretical yield of calcium oxalate would be expected? If only 0.2995 g of calcium oxalate is collected, what percentage of the theoretical yield does that represent?

Interpretation:

The theoretical yield and percentage yield of calcium oxalate should be calculated.

Concept Introduction:

A balanced chemical equation is an equation that contains same number of atoms as well as of each element of reactants and products of reaction.

For example, the reaction between lead sulphide and oxygen is as follows:

2 PbS + 3 O2→2PbO + 2SO2 Reactants Products

The limiting reactant in a particular reaction has due to following properties:

1. Limiting reactant completely reacted in a particular reaction.
2. Limiting reactant determines the amount of the product in mole.

Theoretical yield is also known as calculated yield. Theoretical yield is the amount of product which is theatrically calculates by the amount of limiting agent. It is the maximum amount of product which is formed in any reaction.

Other name of actual yield is observed yield.

The percentage yield is calculated by the actual or observed experimental yield divided by the theoretical yield and multiplied by 100.

The percentage yield can be calculates by the use of following expression:

Actual yield or given yield Theoretical yield or calculated yield ×100%   

Theoretical yield is the greatest amount of a product possible from a reaction, when assume that the reaction goes to 100% competition.

The balance equation for the calcium and oxalate ions is as follows:

Ca2+ (aq)+C2O42-(aq)→CaC2O4(s)

Given:

Amount of Ca2+ = 0.1014 g

Calculation:

Number of moles of Ca2+ is calculated as follows:

Number of moles = mass in gmolar mass=0.1014g40.078 g/mol=0.00253 moles Ca2+

Now calculated the theoretical amount of CaC2O4 as follows:

0.00253 moles Ca2+× 1