1: An open bottle in the lab contains crystals of Na2 SO4 . The temperature is 25 °C, the pressure 1 bar, and the relative humidity 85%. Determine whether the formation of the decahydrate according to the reaction below,
Na2 SO4 + 10H2 O = Na2 SO4 · 10H2O,
can take place under these conditions. What is the minimum relative humidity that will allow the reaction to proceed in the forward direction?