Lab report

Topics: Solubility, Solvent, Ethanol Pages: 3 (659 words) Published: March 6, 2014
EXPERIMENT 5
SEPARATION OF A MIXTURE INTO ITS COMPONENTS
BY FRACTIONAL CRYSTALLIZATION


Introduction:
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.

Goals:
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.

Procedure:
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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