21. The temperature of the cooling water as it leaves the hot engine of an automobile is 240 °F. After it passes through the radiator it has a temperature of 175 °F. Calculate the amount of heat transferred from the engine to the surroundings by one gallon of water with a specific heat of 4.184 J/g °C.

In an experiment, 26.5 g of metal was heated to 98.0°C and then quickly transferred to 150.0 g of water in a calorimeter. The initial temperature of the water was 22.5°C, and the final temperature after the addition of the metal was 32.5°C. Assume the calorimeter behaves ideally and does not absorb or release heat.

How much heat must be added to a 38-g sample of aluminum to increase its temperature by 250.0°C? The specific heat capacity for aluminum is 0.902 J/g°C.

A 325-g piece of gold at 427°C is dropped into 200.0 mL of water at 22.0°C. the specific heat of gold is 0.131 J/g°C. calculate the final temperature of the mixture. (assume no heat loss to the surroundings)

Which of the reactions are exothermic? 2 Mg(s) + O,(g) → 2 MgO(s) + heat O NH, (g) + HCI(g) → NH,CI(s) + heat AgCl(s) + heat – Ag*(aq) + Cl¯(aq) 2 Fe, 0, (s) + 3 C(s) + heat → 4Fe(s) + 3 CO, (g) O C(graphite) + 0,(g) → CO,(g) + heat O CH, (g) + 20,(g) → CO,(g) + 2 H,O(1) + heat

The temperature of the cooling water as it leaves the hot engine of an automobile is 240 °F. After it passes through the radiator it has a temperature of 175 °F. Calculate the amount of heat transferred from the engine to the surroundings by 10 grams of water with a specific heat of 4.184 J/g °C.

A 4.81 g sample of an unknown salt (MM = 116.82 g/mol) is dissolved in 150.00 g water in a coffee cup calorimeter. Before placing the sample in the water, the temperature of the salt and water is 23.72°C. After the salt has completely dissolved, the temperature of the solution is 28.54°C.   If 3.12 × 10³ J of heat was gained by the solution, what is the total heat for the dissolution reaction of the 4.81 g of salt?   How many moles of the unknown salt were used in the reaction ?     _______ J?

What mass of water will change its temperature by 10 °C when 975 J of heat is added? The specific heat of water is 4.18 J/g 0C

1. A thermometer placed in a solution undergoing a chemical reaction indicates an increase in temperature as the reaction proceeds. Is this reaction endothermic or exothermic? Describe if heat energy is lost or gained from the reaction (the system) to the surroundings. What is the sign of the enthalpy change (AH) of this reaction? 2. A student performs a reaction and determines the enthalpy change (AH) to be 31.4 kJ. Will the temperature of the surrounding solution increase or decrease as a result of this chemical process? 3. If you hold 3 grams of ice in your hand at room temperature, your hand will become cold. a) Is the reaction H,O(s) – H,O(1) endothermic or exothermic? b) In which direction does heat flow?

A metal object with mass of 21.4 g is heated to 97.0 °C and then transferred to an insulated container containing 81.7 g of water at 20.5°C. The water temperature rises and the temperature of the metal object falls until they both reach the same final temperature of 23.1 °C. What is the specific heat of this metal object? Assume that all the heat lost by the metal object is absorbed by the water. cal specific heat: