Lab report

Topics: Solubility, Solvent, Ethanol Pages: 3 (659 words) Published: March 6, 2014

Fractional crystallization is one of the experimental techniques used to separate or purify mixture. Fractional crystallization makes use of the differences of solubility to separate the components of a mixture.

Applying fractional crystallization to separate a mixture of salicylic acid and copper sulfate pentahydrate into its components. Calculate the percent of salicylic acid and copper sulfate pentahy- drate in the mixture.

Block/McKelvy/with contributions from Georgia Perimeter Faculty (2012) - Laboratory Experiments for Chem 1211L & 1212L Cengage Learning (7th ed.) p. 23&24 (Separation of a mixture into its components by fractional crystallization)

Data and result:
Unknown number9
Mass of unknown + beaker69.1607 g
Mass of beaker66.6636 g
Mass of unknown mixture2.4971 g
Salicylic Acid Crystallization
Mass of weighing paper + Salicylic acid1.7468 g
Mass of weighing paper0.9446 g
Mass of Salicylic Acid0.8022 g
Calculation of percent salicylic Acid32.13 %
in original mixture:
% salicylic acid = (m Salicylic Acid : m unknown mixture) x 100%
= (0.8022 : 2.4971) x 100%
= 32.13%
CuSO4.5H2O Crystallization
Mass of weighing paper + CuSO4.5H2O2.6484 g
Mass of weighing paper1.0127 g
Mass of CuSO4.5H2O1.6357 g
Calculation of percent CuSO4.5H2O65.504%
in original mixture:
% CuSO4.5H2O = (m CuSO4.5H2O : m unknown mixture) x 100%
= (1.6357 : 2.4971) x 100%
= 65.504%

Percent of original sample not recovered
100% - ( 32.13% +65.504%) = 2.37%

Comments concerning appearance and purity:
The salicylic acid’s appearance are pure, fine, off-white needles. The copper sulfate pentahydrate ’s appearance first observing are contaminated, white coat outside blue crystals.
Prelab question:
1. Explain briefly why CuSO4 is more soluble in water than in an organic (nonpolar)...
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