chemistry
Complete combustion of a 0.600-g sample of a compound in a bomb calorimeter releases 24.0 kJ of heat. The bomb calorimeter has a mass of 1.30 kg and a specific heat of 3.41 J/(gi°C). If the initial temperature of the calorimeter is 25.5°C, what is its final temperature?
a
How does the potential-energy diagram for a reaction indicate whether the reaction is endothermic or exothermic? An endothermic reaction has reactants that are lower in energy than products because energy is absorbed to form the products. An endothermic reaction has reactants that are higher in energy than products because energy is released to form the products. An exothermic reaction has reactants that are lower in energy than products because energy is released to form the products. An exothermic reaction has reactants that are higher in energy than products because energy is absorbed to form the products.
a
Iron reacts with oxygen in a chemical hand-warmer. How should this reaction be categorized? as an exothermic process because it releases heat as an endothermic process because it releases heat as an exothermic process because it absorbs heat as an endothermic process because it absorbs heat
a
What is the specific heat of a substance if a mass of 10.0 kg increases in temperature from 10.0°C to 70.0°C when 2,520 J of heat is applied?
a
When 40.0 mL of 1.00 M H2SO4 is added to 80.0 mL of 1.00 M NaOH at 20.00°C in a coffee cup calorimeter, the temperature of the aqueous solution increases to 29.20°C. If the mass of the solution is 120.0 g and the specific heat of the calorimeter and solution is 4.184 J/g • °C, how much heat is given off in the reaction? (Ignore the mass of the calorimeter in the calculation.)
a
Which answer defines exothermic reaction? a process in which energy is released as heat a process in which energy is absorbed as heat a process in which energy is stored and released a process in which energy is not present in a system
a
Which reaction is exothermic?
a
Which statement about exothermic reactions is accurate? As reactants form products, the potential energy decreases. As reactants form products, the potential energy increases. Thermal energy is transferred from the product to the reacting substances. Thermal energy is transferred from the surroundings to the reacting substances.
a
Which statement best describes why specific heat capacity is often more useful than heat capacity for scientists when comparing two materials?
a
Which statement defines calorimeter?
a
A baker touches a pie right after taking it out of the oven. Which statement best explains why the pie feels hot? Molecules in the skin move faster than molecules in the pie, so heat is transferred to the pie. Molecules in the pie move faster than molecules in the skin, so heat is transferred to the skin. Molecules in the skin move faster than molecules in the pie, so heat is transferred to the skin. Molecules in the pie move faster than molecules in the skin, so heat is transferred to the pie.
b
A student touches a freshly baked cake that was taken out of the oven. Which best explains why the cake feels hot? Molecules in the skin are moving faster than molecules in the cake. Molecules in the cake are moving faster than molecules in the skin. The kinetic energy of molecules in the cake is more than the energy in the baking tray. The kinetic energy of molecules in the baking tray is more than the energy in the cake.
b
A sample of an unknown substance has a mass of 0.465 kg. If 3,000.0 J of heat is required to heat the substance from 50.0°C to 100.0°C, what is the specific heat of the substance?
c
A sample of hexane (C6H14) has a mass of 0.580 g. The sample is burned in a bomb calorimeter that has a mass of 1.900 kg and a specific heat of 3.21 J/giK. What amount of heat is produced during the combustion of hexane if the temperature of the calorimeter increases by 4.542 K?
c
The diagram below shows the temperature dropping from 80°C to 20°C. mc002-1.jpg Molecules that have longer arrows are moving faster. Which statement describes what is happening in this system? Molecules vibrate more as temperature decreases. Temperature is not related to the average kinetic energy of a system. Kinetic energy decreases as temperature decreases. There is no change in average kinetic energy between these two systems.
c
Which statement defines the heat capacity of a sample?
c
Which event is endothermic? the burning of a match the change of water vapor to a liquid the combustion of propane gas the melting of ice
d
Which statement describes how a basic coffee cup calorimeter works?
d
Which units express heat capacity?
a
Which units express specific heat capacity?
b
What would be the greatest difference in using an open ceramic coffee mug rather than an insulated mug with a lid as a calorimeter?
d
wo different gases are stored in separate closed containers. If both gases have a temperature of 50°C, which statement is true? The thermal energies of gas molecules in the two containers are unrelated. The gas molecules in both containers will absorb heat from the surroundings. The molecules in one gas will transfer energy to the molecules in the other gas. The gas molecules in both containers have the same average kinetic energy.
d
Two samples of carbon come into contact. Heat will transfer from Sample A to Sample B if the average kinetic energy of Sample A's atoms is the average kinetic energy of Sample B's atoms.
greater than
