Question

What are deltaTb and deltaTf for an aqueous solution that is 1.5g nacl in 0.250kg h2o? Given Kb=0.51 C/m and kr=1.86 C/m

Answer 1

Answer:

$T_f$ for given question is 2.79 and $T_b$ is 0.52

$\Delta T_b = I \times K_b \times m$ {i- vant hoff’s constant ; Kb- constant ; m molarity }

M = no. of moles of the solute present in one kg of solution

Let the weight of amount of solute be “w” and its molecular mass be “M”

Let the mass of the solvent in the given question be “x”

$\Delta T_b = I \times K_b \times (w/M)/ x$

$\Delta T_b = I \times K_b \times w/Mx$

$\Delta T_b = 1 \times 0.51 \times1.5/(0.250 \times 58.44) = 0.052$

$\Delta T_f = M \times K_f = 1.86 \times 1.5 = 2.79$