A 27.5g piece of aluminum sits in a room and cools.  It loses 6120.0 J of heat. If the initial temperature of aluminum is 157.3°C, what is the final temperature?  The specific heat capacity of aluminum is 0.900 J/g°C.

An iron skillet weighing 1.63 kg is heated on a stove to 178C. Suppose the skillet is cooled to room temperature, 21C. How much heat energy (in joules) must be removed to affect this cooling? The specific heat of iron is 0.449 J/(gC).

Classify each process as exothermic or endothermic. (a) ice melts (b) gasoline burns (c) steam condenses (d) reactants products, H = 50 kJ

Thermal Interactions Part 1: In an insulated container, you mix 200. g of water at 80C with 100. g of water at 20C. After mixing, the temperature of the water is 60C. a How much did the temperature of the hot water change? How much did the temperature of the cold water change? Compare the magnitudes (positive values) of these changes. b During the mixing, how did the heat transfer occur: from hot water to cold, or from cold water to hot? c What quantity of heat was transferred from one sample to the other? d How does the quantity of heat transferred to or from the hot-water sample compare with the quantity of heat transferred to or from the cold-water sample? e Knowing these relative quantities of heat, why is the temperature change of the cold water greater than the magnitude of the temperature change of the hot water. f A sample of hot water is mixed with a sample of cold water that has twice its mass. Predict the temperature change of each of the samples. g You mix two samples of water, and one increases by 20C, while the other drops by 60C. Which of the samples has less mass? How do the masses of the two water samples compare? h A 7-g sample of hot water is mixed with a 3-g sample of cold water. How do the temperature changes of the two water samples compare? Part 2: A sample of water is heated from 10C to 50C. Can you calculate the amount of heat added to the water sample that caused this temperature change? If not, what information do you need to perform this calculation? Part 3: Two samples of water are heated from 20C to 60C. One of the samples requires twice as much heat to bring about this temperature change as the other. How do the masses of the two water samples compare? Explain your reasoning.

Enthalpy a A 100.-g sample of water is placed in an insulated container and allowed to come to room temperature at 21C. To heat the water sample to 41C, how much heat must you add to it? b Consider the hypothetical reaction,2X(aq)+Y(l)X2Y(aq)being run in an insulated container that contains 100. g of solution. If the temperature of the solution changes from 21C to 31C, how much heat does the chemical reaction produce? How does this answer compare with that in part a? (You can assume that this solution is so dilute that it has the same heat capacity as pure water.) c If you wanted the temperature of 100. g of this solution to increase from 21C to 51C, how much heat would you have to add to it? (Try to answer this question without using a formula.) d If you had added 0.02 mol of X and 0.01 mol of Y to form the solution in part b, how many moles of X and Y would you need to bring about the temperature change described in part c. e Judging on the basis of your answers so far, what is the enthalpy of the reaction 2X(aq) + Y(l) X2Y(aq)?

An aluminum kettle weighs 1.05 kg. (a) What is the heat capacity of the kettle? (b) How much heat is required to increase the temperature of this kettle from 23.0 C to 99.0 C? (c) How much heat is required to heat this kettle from 23.0 C to 99.0 C if it contains 1.25 L of water (density of 0.997 g/mL and a specific heat of 4.184 J/g C)?

Swimming Pool A swimming pool measuring 20.0m12.5m is filled with water to a depth of 3.75m. If the initial temperature is 18.4°C, how much heatmust be added to the water to raise its temperature to29.0°C? Assume that the density of water is 1.000 g/mL.

You have two samples of different metals, metal A and metal B, each having the same mass. You heat both metals to 95C and then place each one into separate beakers containing the same quantity of water at 25C. a You measure the temperatures of the water in the two beakers when each metal has cooled by 10C and find that the temperature of the water with metal A is higher than the temperature of the water with metal B. Which metal has the greater specific heat? Explain. b After waiting a period of time, the temperature of the water in each beaker rises to a maximum value. In which beaker does the water temperature rise to the higher value, the one with metal A or the one with metal B? Explain.

Which of the following is an endothermic process? combustion of gasoline in a car engine i>sublimation of carbon dioxide: water condensing on a cold pipe freezing juice to make popsicles

Hydrogen is an ideal fuel in many respects; for example, the product of its combustion, water, is nonpolluting. The heat given off in burning hydrogen to gaseous water is 5.16 104 Btu per pound. What is this heat energy in joules per gram? (1 Btu = 252 cal; see also Table 1.4.)