At 60°C → 40 g for every 100 g H2O
For 200 g H2O, 80 grams is dissolved
At 20°C → 10 g for every 100 g H2O
A mixture of 100 g of K2Cr2O7 and 200 g of water is stirred at 60 C until no more of the salt dissolves. The resulting solution is poured off, leaving the undissolved solid behind. The solution is now cooled to 20 C. What mass of K2Cr2O7 crystallizes from the solution during the cooling?