Calculate the heat energy released when 28.9 g of liquid mercury at 25.00 °C is converted to solid mercury at its melting point.

Question

I need help solving this problem.

Answer 1

The specific heat capacity for Hg is 0.140 J/g·°C, its heat of fusion is 11.6 J/g, and the melting point is -38.83º C.

 

Liquid mercury will release some of its internal energy to the surroundings when it cools and then solidifies.

 

 

Cooling: Q = mcΔT

 

Q = (28.9 g)(0.140 J/g·°C)(-38.83° C - 25.00° C) = -258 J

 

 

Solidification: Q = mL = (28.9 g)(-11.6 J/g) = -335 J

 

 

The total energy released is -258 J - 335 J = -593 J

 

The negative sign represents energy lost by the system.

 

 

Answer 2

Hi Denise,

 

q = ms Δ t (equation for calculating the heat change)

 

specific heat "s" for mercury (Hg) is 0.139.

melting point for Hg is -38.87 C

 

28.9 x 0.139 x (25.00 - -38.87)

28.9 x 0.139 x (63.87) = 256.572177 J

 

q = 0.257 kJ

 

Good luck to you.