Question

A sample of pure oxalic acid hydrate was obtained by extraction from a plant called Snake Tongue. A 3.000 g sample of the material was heated carefully in a vacuum oven until no more mass was lost from the sample. After heating, the final weight of the material was 2.143 g. What is the formula of the oxalic acid hydrate. (COOH)_2 middot H_2O? (mol.wt. (COOH)_2 = 90.0 g/mol) An ore sample is known to contain copper sulfate pentahydrate, CuSO_4 middot 5 H_2O. If a 10.000 g sample of the ore loses 0.336 g of water when heated strongly, what is the maximum quantity of CuSO_4 middot 5 H_2O that could be in the sample? (fwt. CuSO_4 middot 5 H_2O = 249.55g/mol)

Answer 1

COOH OOH Chemical Formula: C 04 3.00 g 2.143 g Molecular Weight: 90.03 3-2.143 0.857 0.857 x 100-285690 water is lost Chemical Formula: H2O Molecular Weight: 18.02 Let us start monohydrate 18.02 x 100-16.76 % ( it not equal to the water lost during heating 90.0318.02 36.04 x 100 = 28 06 % t is equal to the water equal lost while dry 90.03 +2(18.02) thus it is dihydrate (COOH2 2H2o CuSO4 5HO it is a composition of 1 mole of CuSO4 adn 5 moles of water CuSO4 0.336 g 18-0.01866 moles of water Chemical Formula: CuSO4 Molecular Weight: 159.61 Thus, 0.01866 5 3.732 x 10.5 x 159.61 0.5956 g of CuSO4 0,5956 +0018660.9316 g CuSO4. 5H20