Chemistry Practice Problems Calorimetry Practice Problems Solution: A hot lump of 106.2 g of an unknown substance init...

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Solution: A hot lump of 106.2 g of an unknown substance initially at 153.2°C is placed in 35.0 mL of water initially at 25.0°C and allowed to reach thermal equilibrium. The final temperature of the system is 53.2°C. What is the identity of the unknown substance? Assume no heat is lost to the surroundings.

Problem

A hot lump of 106.2 g of an unknown substance initially at 153.2°C is placed in 35.0 mL of water initially at 25.0°C and allowed to reach thermal equilibrium. The final temperature of the system is 53.2°C. What is the identity of the unknown substance? Assume no heat is lost to the surroundings.

Solution

We’re being asked to determine the identity of the unknown substance in the given system.

Recall that heat (q) can be calculated using the following equation:

q=mcT

q = heat, J

+qabsorbs heat
–qloses heat

 m = mass (g)
 c = specific heat capacity = J/(g·°C)
 ΔT = Tf – Ti = (°C)


Based on the given system:

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