2. QUESTION 1””
•1. What is the final temperature when a 3.0 kg gold bar
at 99°C is dropped into 0.22 kg of water at 25°C?
•3.0 kg x 0.129 j/gC x (Tf-99C) + 0.22 kg x 4.184 j/gC x
Tf - 25C) = 0 0.387Tf - 38.313 + 0.9205Tf - 23.012 = 0
1.307Tf - 61.325 = 0 1.307Tf = 61.325 Tf = 46.9
degrees C
3. QUESTION 2””
•2. A 0.225 kg sample of tin initially at 97.5°C is dropped into
0.115 kg of water. The initial temperature of the water is 10.0°C.
If the specific heat capacity of tin is 230 J/kg •°C, what is the
final equilibrium temperature of the tin-water mixture?
•Energy given by copper = Energy taken by water
.225 X 230 X(97.5-t) = .115 X 4186 X(t-10)
97.5-t = 9.302(t-10)
t=(97.5 + 93.02)/10.302
t= 18.493 degree Celsius
4. QUESTION 3”””
•3. Brass is an alloy made from copper and zinc. A
0.59 kg brass sample at 98.0°C is dropped into
2.80 kg of water at 5.0°C. If the equilibrium
temperature is 6.8°C, what is the specific heat
capacity of brass?
•m_brass ∙ c_brass ∙ ∆T_brass = m_water ∙ c_water ∙ ∆T_water
=>
c_brass = c_water ∙ (m_water/m_brass) ∙ (∆T_water/∆T_brass)
= 4186J/kg°C ∙ (2.8kg/0.59kg) ∙ ((6.8°C - 5°C) / (98°C - 6.8°C))
= 392J/kg
5. QUESTION 4”””
•4. A hot, just-minted copper coin is placed in 101 g
of water to cool. The
•water temperature changes by 8.39°C, and the
temperature of the coin
•changes by 68.0°C.What is the mass of the coin?
•135 g
