Calculate the heat energy released when 17.7 g of liquid mercury at 25.00 °c is converted to solid mercury at its melting point.

Answer;

Q = 359.2-J  

Explanation;

Given that;

Constants for mercury at 1 atm  

Heat capacity of Hg(l) is 28.0 J/(mol*K)  

melting point is 234.32 K  

Enthalpy of fusion is 2.29 kJ/mol

17.7-g Hg / 200.6g/mol = 0.0882 mol Hg;

°C + 273 = 298 K;

2.29-kJ/mol = 2290-J/mol  

Q = (m x ΔT x Cp) + (m x Hf)  

Q = 0.0882-mol x (298 - 234.32) x 28.0-J/mol*K) + (0.0882-mol x 2290-J/mol)  

Q = 157.26-J + 201.978-J  

Q = 359.2-J  

Q=359-J (3 sig fig allowed due to 17.7-g given in problem)

no. dot product   =0 when vecs at right angles