Determination of water of hydration Essay

Observation of copper sulfate No copper sulfate Light blue After heating for about 2-3 minutes, of the powder turns lighter and then into grey-white. Water released as vapor is observed from this point. After heating for another 2-3 minutes, of the powder turns into grey-white. After heating for 10 minutes, the whole part of the powder turns into grey-white with some parts of light green The whole part of the powder remains grey-white with some parts of light green The whole part of the powder remains grey-white with some parts of light green * Mass of hydrated copper sulfate (g) = (46.08 à ¯Ã‚ ¿Ã‚ ½ 0.01) – (43.78 à ¯Ã‚ ¿Ã‚ ½ 0.01) = 2.30 à ¯Ã‚ ¿Ã‚ ½ 0.02 (g) * Mass of water (g) = ( 46.08 à ¯Ã‚ ¿Ã‚ ½ 0.01) – (45.22 à ¯Ã‚ ¿Ã‚ ½ 0.01) = 0.86 à ¯Ã‚ ¿Ã‚ ½ 0.02 (g) * General reaction: hydrate anhydrous salt + water CuSO4.xH2O CuSO4 + xH2O m 2.30 à ¯Ã‚ ¿Ã‚ ½ 0.02 (g) 0.86 à ¯Ã‚ ¿Ã‚ ½ 0.02 (g) M 160 +18x (g/mol) 18x (g/mol) * n xH2O (mol) = n CuSO4.xH2O = = (0.86 )(160 + 18x) = )18x 160(0.86 ) + 18x(0.86 ) = )18x 160(0.86 ) = 18x(1.44 0.04) x = = = 5.3 à ¯Ã‚ ¿Ã‚ ½ 0.3 Conclusion: The value of x in CuSO4.xH2O is quite similar to the value on the label (literal value) of the hydrated copper sulfate jar (% of difference is 6%) Evaluation Limitations Effects Improvements The number of experiments carried out is not enough (Random error) If the data obtained are inaccurate; as a result, the value of x calculated will be inaccurate Do the experiment many times When cooling the crucible, water can be reformed in copper sulfate (random error) Weight of the crucible may increase Use a data logger computer to take the mass of the crucible continuously until the mass remains unchanged The flame is too strong (random error) Some copper sulfate molecules may be decomposed Keep the flame at a reasonable height and temperature