what is the solubility of sodium chloride at 5c and 40c?

Question

what is the solubility of sodium chloride at 5c and 40c?

Answer 1

The solubility of sodium chloride is the square root of the solubility constant, K_sp. This can be calculated from thermodynamics, given two constants - the enthalpy of dissolution and the entropy of dissolution.  The equation is ln(K_sp) = -ΔH⁰/RT +ΔS⁰/R . The K_sp of NaCl is quite large, poking around the internet I get the value of 37.7 M².  According to wikipedia, the value of ΔH⁰ is +3.87 kJ/mol.  So, to calculate all the parameters,  we use (ln(37.7) + 3.87/(0.0083145*298))*8.3145  = ΔS⁰ = 43.17 J/M•K .  so, ln(K_sp) = -3.87/(0.0083145*(298-20)) + 43.17/8.3145 @ 5 degrees C and  ln(Ksp) = -3.87/(0.0083145*(298+15)) + 43.17/8.3145 @ 40 degrees C.  This yields Ksp = 33.7 @ 5 (Solubility is 5.8 molar) and Ksp - 40.65 M² (Solubility is 6.37 molar).

Answer 2

I don't think you have enough information to do any calculations.  You could do an experiment take 100mL of water cool the water to 5 degrees Celsius or heat it and see how much dissolves.

 

You should find more dissolves in the warmer water.

 

Sodium chloride is an ionic solvent and so it should be fairly soluble.  At 20 C, 35.7g dissolves and at 100 C   39.1g should dissolve in 100 mL of water.

Answer 3

At 40C: it is 36.37g/100gH20