Answer to Question #149869 in General Chemistry for Megan Wakley

Question

A 175.0 g sample of ice at 0.0 ̊C ends up as liquid water at 45.0 ̊C. How much energy is involved in this change?

Answer 1

Two processes occur here that require energy. (i) Phase change(melting), and (ii) temperature change;

I. Q during Phase change

Q₁=mL_f

$=\dfrac{175.0}{1000}Kgx334J/Kg$

= 58.45J

II. Q for temperature change

Q₂=mC$\Delta$T

$=175.0gx\dfrac{4.18J}{g^oC} x 45.0^oC$

= 32,917.5J

Add up for total energy

Q_T=Q₁ + Q₂

= 58.45J + 32,917.5J

= 32,975.98J

= 32.98kJ