The solubility of potassium nitrate in water at 75°C is 155 g/100 g and at 20°C is 31 g/100 g. What mass of potassium nitrate must be taken to give 100 g of crystals when a
saturated solution at 75°C is cooled to 20°C?

explanation: no but i do not usually comment

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.

yes

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