An impure sample of Na2 SO4 has a mass of 1.56 g. This sample is dissolved and allowed to react with BaCl2 solution. The precipitate has a mass of 2.15 g Calculate the percentage purity of Na2 SO4 in the original sample.

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.