8. Thermochemistry

Which process best explains how ice cools a warm drink?

How much energy must be removed from a 125 g sample of benzene (molar mass = 78.11 g/mol) at 425.0 K to liquify the sample and lower the temperature to 335.0 K? The following physical data may be useful: ΔHvap = 33.9 kJ/mol, ΔHfus = 9.8 kJ/mol, Cliq = 1.74 J/g·K.

A 2.0 kg metal weight at 80 °C is placed into 1.0 kg of water at 20 °C in an insulated container. Assuming no heat is lost to the surroundings and the specific heat capacity of the metal is 0.45 J/g·°C and that of water is 4.18 J/g·°C, what is the final temperature of both the weight and the water at thermal equilibrium?

An 80.0 g sample of metal, initially at 96.0 °C, is placed into 150.0 g of water initially at 26.0 °C in a calorimeter. The final temperature of the water is 28.1 °C. What is the identity of the metal? (The specific heat of water is 4.18 J/g°C.)

Why is it important that the thermometer does not touch the sides or bottom of the test tube when measuring temperature during an experiment involving thermal equilibrium?

When water is heated in an insulated container and reaches thermal equilibrium with its surroundings, which of the following statements is true?

A sheet of gold weighing 10.0 g and at a temperature of 18.0°C is placed on a sheet of iron weighing 20.0 g and at a temperature of 55.6°C. What is the final temperature of the combined metals? The specific heats of iron and gold are, respectively, 0.444 J/g°C and 0.129 J/g°C.

A 32.8 g iron rod, initially at 22.8 °C, is submerged into an unknown mass of water at 64.0 °C, in an insulated container. The final temperature of the mixture upon reaching thermal equilibrium is 59.5 °C. What is the mass of water?

A piece of iron (mass = 25.0 g) at 398 K is placed in a styrofoam coffee cup containing 25.0 mL of water at 298 K. Assuming that no heat is lost to the cup or the surroundings, what will the final temperature of the water be? The specific heat capacity of iron is 0.449 J/g·K and the specific heat capacity of water is 4.18 J/g·K.

A calorimeter contains 365 g of water at 30.0 °C. A 29.3-g sample of ice (at -11.0 °C) is added to the water in the calorimeter, and eventually all of the ice melts. Calculate the final temperature of the water. Assume no heat is lost to the calorimeter.

A 10.69-g block of solid platinum at 66.41°C is immersed in a 23.93-g pool of liquid ethanol with a temperature of 12.95°C. When thermal equilibrium is reached, what is the final temperature of the platinum and ethanol? Specific heat capacities: platinum = 0.133 J/g°C, ethanol = 2.44 J/g°C.

How much energy is needed to vaporize 75.0 g of diethyl ether (C4H10O) at its boiling point (34.6 °C), given that ΔHvap of diethyl ether = 26.5 kJ/mol?

A 140.0 g sample of water at 20.0 °C is mixed with 100.0 g of a certain metal at 95.0 °C. After thermal equilibrium is established, the temperature of the mixture is 24.6 °C. What is the specific heat capacity of the metal?

Two bodies A and B are placed in thermal contact inside an insulated container. After some time, their temperatures become constant and equal. Which statement correctly describes the condition for thermal equilibrium between A and B?