Answer to Question #23853 in Physical Chemistry for pejman

Question

a sample of zinc is placed in the ice calorimeter. if 0.0657 g of zinc causes a decrease of 0.109 ml in the in the ice/water volume of the calorimeter, what is the enthalpy change, per mole of zinc, for the below reaction?

Zn+2H*(aq) --> Zn*(aq)+H2
"H" charge is "+1"
"Zn" charge is"+2"

Answer 1

Ice has a density of 0.9167 g/cm³ at 0 °C, whereas water has a density of 0.9998 g/cm³ at the same temperature
So 0.9167g of ice converted to water give a change of (0.9167 - 0.9998) cm^3 ---> 0.0831 cm^3/ 0.9167 g ice melted
g ice melted = 0.109cm^3/(0.0831 cm^3/0.9167 g ice melted) = 0.0907 g ice melted
heat to melt ice = (0.0907 g ice melted) * (333.55J/g) = 30,237 J from reaction
J/mole Zn =30,237 J from reaction / (0.0657 g Zn/ 65.38 g/mole) = 30237 J/mole Zn