Copper Sulfate Mole Ratio Lab

Copper Sulfate Mole Ratio Lab

Analysis

Table 1: Primary data

Qualitative observations

Post-burns, the CuSO4 became whiter, as opposed to the blue of the hydrate. The longer it burnt, the more white it appeared. However, the first burn continued for too long, and the CuSO4 began to appear slightly grey.

Table 2: Mass of chemicals

*Uncertainties calculated by adding uncertainties of addends (according to Table 1, 2)

        Ex: Uncertainty of hydrate = 0.01 + 0.01 = 0.02

**Masses calculated by subtracting mass of crucible + cover from mass of crucible + cover + substance (Table 1)

        Ex: Mass of hydrate = (Mass of crucible + cover + hydrate) - (Mass of crucible + cover)

        = 24.25 - 22.56 = 1.69

*** Mass of H2O lost = (Mass of hydrate) - (Mass of CuSO4-- post second burn) = 1.69 -

1.05 = 0.64

Table 3: Molar masses and moles of substances

*According to Sargent-Welch Scientific Company. Calculated by adding masses of constituent parts

        Ex: Molar mass of CuSO4 = Mass of Cu + Mass of S + Mass of O * 4 = 63.546 + 32.06 +

15.9994 * 4 = 159.60

**Numbers in brackets are not significant

*** Mols calculated by dividing mass of substance by molar mass of substance (Table 2)

        Ex: Moles of CuSO4 = mass of CuSO4 / molar mass of CuSO4 = 1.05 / 159.6036 =

0.00658

****Uncertainty calculated by multiplying decimal uncertainty of mass of substance by moles of substance (Table 2)

        Ex: Uncertainty of mols of CuSO4 = (Uncertainty of mass of CuSO4 / Mass of CuSO4) *

moles of CuSO4  = 0.02 / 1.05 * 0.006578799 = 0.0001

Mole ratio

• Divide moles of CuSO4 and H2O by the moles of CuSO4

• CuSO4: 0.0065(78799) / 0.0065(78799) = 1.0 ± 0 mol

• Uncertainty calculated by multiplying sum of decimal uncertainties of moles of CuSO4 to mole ratio = (0.0001 * 2) / 0.006578799 * 1 = 0.03 = effectively zero (Table 2, 3)

• H2O: 0.035(5255562) / 0.0065(78799) = 5.4(00006323) ± 0.4 mol

• Mole ratio: anhydrous saltwater= 1.0 ± 0.05.4 ± 0.04

Evaluation

        The goal of the lab was to determine the mole ratio of CuSO4 and H2O. By translating the mass of the substances into moles, I determined that the mole ratio of CuSO4 : H2O was roughly 1:5.4. According to EndMemo Chemistry, the ratio should have been 1:5 (2017). Therefore, the conclusion was relatively accurate. The result was slightly too small, but the moles of H2O is ±0.4, which would make the mole ratio exactly correct.

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