Determine the formula of the hydrate in hydrated copper (II) sulfate empirically, i.e. to find x in the formula: (CuSO4 · xH2O) and thus ascertain the degree of hydration.

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IB Chemistry – Practical Report

Name: Chris Bolton

Partner: Jamie Gearing

Date(s) Conducted: 14/05/04

Topic: Stoichiometry

Experiment:         The Degree of Hydration of Copper (II) Sulfate, CuSO4 · xH2O

Aim:

To determine the formula of the hydrate in hydrated copper (II) sulfate empirically, i.e. to find x in the formula:  (CuSO4 · xH2O) and thus ascertain the degree of hydration.  

Apparatus:

        

MATERIALS:        Hydrated copper (II) sufate

GENERAL:        Heatproof mat, tripod, Bunsen burner, pipeclay triangle, crucible, metal tongs, glass mixing rod, spatula, electronic balance

 SAFETY:        Lab coat and safety glasses to be worn at all times

Method:

Refer to attached worksheet for given method

        AMMENDMENTS/ADDITIONS/SAFETY PRECAUTIONS:

  • If required, manipulate CuSO4 · xH2O with glass rod during heating to assist process
  • Ensure that heating is gentle (as indicated) to avoid either damage to the crucible or overheating the sample (this could result in impurities in the anhydrous compound)
  • Ensure to control Bunsen flame to avoid blackening pipeclay triangle or crucible

Results:

                Fig. 1

                A Table to Show Key Masses

                NOTE: Systematic error associated with electronic balance is consistently ± 0.002 g

        

        Initial observations of hydrated copper (II) sulfate:        Blue crystalline solid

Fig. 2

A Table to Show Results of Gentle Heating of CuSO4 · xH2O

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Collating, Interpreting and Analysing Results:

        Known Values

        Mass of Crucible: 8.024g ± 0.002g

Mass of Crucible and CuSO4 · xH2O: 10.058g ± 0.002g

Mass of Crucible and CuSO4 · xH2O after heating: 9.291g ± 0.002g

Calculation of Key Values

        Mass of CuSO4 · xH2O:

                m(CuSO4 · xH2O) = m(Crucible and CuSO4 · xH2O) – m(Crucible)

                                  = 10.058 – 8.024

                m(CuSO4 · xH2O) = 2.034g ± 0.004g

        Mass of CuSO4:

                Calculated by finding mass of water loss

                m(CuSO4) = m(Crucible and CuSO4 · xH2O after heating) – m(Crucible)                

                           = 9.291 – 8.024

                m(CuSO4) = 1.267g ± 0.004g

∴        Mass of xH2O:

                Calculated by subtracting the mass ...

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