A chemist attempts to prepare some very pure crystals of borax (sodium tetraborate,
Na,B,0, 10H,0) by dissolving 100g of Na,B,0, in 200g of boiling water. He then
carefully cools the solution slowly until some Na,B,O, 10H,0 crystallizes out. Cal-
culate the g of Na,B,O, 10H,0 recovered in the crystals per 100 g of total initial so-
lution (Na,B,O, plus H,0), if the residual solution at 55°C after the crystals are re-
moved contains 12.4% Na,B,O,.