look at your solubility curves.
Find the KCl, where it crosses the 80C line. Read the number. That is usually per 100 g of water, so multiply it by .35.\\http://www.sciencegeek.net/Chemistry/taters/solubility.htm
I read it at 52g/100gwater, or multiplying by .35, about 18 g KCl
What mass of KCl will dissolve in 35g H2O at 80 degrees C
1 answer