Question

2) A person pours 400 g of water at 45°C into an 855-g aluminum container with an initial temperature of 10°c. The specific heat of aluminum is 900 J/(kg-K) and that of water is 4190 J/(kg K). What is the final temperature of assuming no heat is exchanged with the surroundings? A) 3 B) 35°C D) 28°C E) 33°C 3) A heat engine with aneffic ency of 300% performs 300 of work. How much heat is discharged to the lower C) 5830J temperature reservoir? D) 8330 J E) 7030 J A)750 J B) 1350 J 4) What is the mass density of argon gas at pressure 2.00 105 N/m2 and at temperature 400 K? The mean atomic mass of argon is 39.948 g/mol and the ideal gas constant is R - 8.314 J/mol K-0.0821 L atm/mol. K. D) 1.80 kg/m3B) 1.20 kg/m3 A) 1.60 kg/m3 B2.40 kg/m3 ) 1.00 kg/m3 5) A 3.2-L volume of neon gas (Ne) is at a pressure of 5,3 atm and a temperature of 330 K. The atomic mass of is 20.2 g/mol, Avogadro's number is 6.022 1023 molecules/mol. The mass of the neon gas in kg is closest to B) 780 D) 7.8 00 E) 0.008 A) 3.8 6) A blacksmith is flattening a steel plate that measures 10 cm x 20 em x 1 mm. He has heated the plate to 845 K. If the emissivity of the plate is 0.75, what is the total rate at which it radiates energy? The Stefan-Boltzmann constant is 5,670 10-8 W/m2. K4. Ignore any heat it receives from the surroundings. A) 360 W B)760 w C) 850 W D) 790 W E) 880 W

Answer 1

Heat lost water = Heat gained by Al = > m_w c_w DT_w = m_AL C_AL DT_AL = > (400)(4190) (45_t) = (855)(900) (T - 10) = > 75,420,000 - 1,676,000T = 769,500T - 7,645,000 = > T[1,676,000 + 769,500] = 75,420,000 + 7,695,000 = > T = 33 degreeC