Question

Two solutions are produced by dissolving 10.0 grams of sodium nitrate in 0.500 kg of water and by dissolving 10.0 grams of calcium nitrate in 0.500 kg of water. Which solution would freeze at a lower temperature? Explain without calculation.

Answer 1

we have 2 solutions

NaNO3 solutions

Ca(NO3)2 solution

moles of NaNO3 = 10.0 / 84.995 = 0.118

moles of Ca(NO3)2 = 10.0 / 164.09 = 0.061

NaNO3 -------------> Na⁺ + NO3^-

0.118 x 2 = 0.236 moles particles present

Ca(NO3)2 --------------> Ca⁺² + 2NO3^-

0.061 x 3 = 0.183 moles particles present

so in NaCl solution more particles present .

so NaCl solution freezes at lower temperature.

higher the particles present in solution lowest the freezing point of the solution.