# Easy calculation

by Winzer
Tags: calculation
 P: 605 1. The problem statement, all variables and given/known data I have .021 moles of H2o and .0137 CaSO4 annhydrous. What is the formula for hydrated calcium? 2. Relevant equations CaSo4*H20-->CaSo4 +H2o 3. The attempt at a solution we divide .0137 by.021 and get .65. We then multipy that by three and get: 2CaSo4*1H20-->2CaSo4 +1H2o Right?
 P: 605 oops that should be 2CaSo4*3H20-->2CaSo4 +3H2o
 P: 605 Here is another Calculation I have to solve. What mass due to waters of crystallization is present in a 50g sample of: CuSo4*5H20? 1 mole of CuSo4=159.61g 5 moles H20= 90.08g Do I just take the ratio of h20 to cuso4 an multply by 50g to obtain mass of h20?
 P: 1,235 Easy calculation To my best knowledge, there are 2 types of hydrates: gypsum or dihydrate: CaSO4.2H2O hemihydrate: CaSO4.(0.5)H2O But the question is really not clear. Can you make it clearer. What do you mean by this: "I have .021 moles of H2o and .0137 CaSO4 annhydrous." What does "I have" mean ??? What is the context of this question? Is it a textbook exercice, then reproduce it completely. Is it a experimental question, then explain more about you procedure.
 Sci Advisor HW Helper PF Gold P: 3,724 If the question is related to an analysis of an unknown hydrate and the values you gave are for the constituent components, the solution is fairly easy. Find the number of moles of each constituent and place these numbers as subscripts for each component. Divide both by the smallest number (of the subscript). This should yield the empirical formula. In the case where fractional numbers result, multiply both subscripts by an integer to remove the fractional value. eg. n moles of X and m moles of Y. first attempt $$(X)_n(Y)_m$$ Using some numbers, 0.03 for n and 0.045 for m this becomes: $$(X)_0._0_3(Y)_0._0_4_5$$ Dividing both subscripts by the smallest number (0.03): $$(X)_1(Y)_1._5$$ multiply both subscripts by '2' to yield: $$X_2Y_3$$ (the correct empirical formula)
 P: 440 for the second problem.... you have to think in terms of moles.... 1 mol of CuSO4.5H2O contains 1 mol CuSO4 and 5 Mol H2O so 50 g of CuSO4.5H2O, which is (50/250) mol = 0.2 mol will contain 0.2 mol CuSO4 and (5*0.2)mol H2O you nneed the mass of H2O present in the 50g.... this corresponds to (5*0.2*mass of 1 mol H2O) = 18 g it's all a matter of proportion.....