Apr. 13, 2015•0 likes•15,686 views

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Science

PERFECT

Mohamed AliFollow

Ch21Universidade Federal de Alfenas

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- 1. Question on Calorimetry made byomar mohamed el wassal Class1-4 PHYSICS
- 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
- 6. THANK YOU