chemistry thermodynamics

An engineer wants to determine an efficient method for condensing large amounts of steam into liquid water. Which constant should she use?

- DELTA H VAP

Which is the best example of potential energy? A. holding a basketball in the air B. rolling a ball across a flat table C. flowing electric current through a wire D. turning on a flashlight in a dark room

A holding a basketball in the air

Old photographic flashbulbs burn magnesium metal in a reaction that causes a flash of brilliant white light. A photographer would need to take care not to suffer burned fingers when trying to replace the hot bulb. What best identifies the energy transformation that occurs in the flashbulb? A: chemical energy to electromagnetic energy and thermal energy B: electromagnetic energy to chemical energy and thermal energy C: chemical energy to electromagnetic energy D: thermal energy to chemical energy

A: chemical energy to electromagnetic energy and thermal energy

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.

As reactants form products, the potential energy decreases.

According to the law of conservation of energy, what will most likely happen in a closed system? A: Energy will be exchanged along with matter. B: Energy will be exchanged, but matter will not be exchanged. C: Energy will be created along with matter. D: Energy will be destroyed, but matter will not be destroyed.

B Energy will be exchanged, but matter will not be exchanged.

A welding torch produces a flame by burning acetylene fuel in the presence of oxygen. The energy released from the acetylene fuel is then used to melt a metal. Which energy transformation happens during this process? Chemical energy turns into thermal energy. Kinetic energy turns into potential energy. Thermal energy turns into electromagnetic energy. Potential energy turns into chemical energy.

Chemical energy turns into thermal energy.

A generator contains a coil that spins to produce an electric current. How is energy transformed by using a generator? A. Thermal energy is transformed to potential energy. B. Thermal energy is transformed to mechanical energy. C. Chemical energy is transformed to electromagnetic energy. D. Mechanical energy is transformed to electromagnetic energy.

D. Mechanical energy is transformed to electromagnetic energy.

Which formula can be used to calculate the enthalpy of solution?

DELTAHSOL=DELTAHSOLUTE+DELTAHSOLVENT+DELTAHMIX

The reaction below proceeds spontaneously at 298 K. NH3(g) +Cl2(g)mc013-1.jpgNH4Cl(s) What is the sign of the entropy change, DELTAS? DELTApgS is negative because the product is less random than the reactants. DELTAS is negative because the reactants are less random than the product. DELTAS is positive because the product is less random than the reactants. DELTAS is positive because the reactants are less random than the product.

DELTAS is negative because the product is less random than the reactants.

Which statement describes the law of conservation of energy? All systems will exchange matter and energy with their surroundings. All systems can exchange energy, but not matter, with their surroundings. Energy cannot be created nor destroyed, but it changes from one form to another. Energy is destroyed in most chemical reactions when new products are formed.

Energy cannot be created nor destroyed, but it changes from one form to another.

Reactant P contains 50 J of energy, and reactant Q contains 35.3 J of energy. The reactants combine to form product PQ, which contains 104 J of energy. What is the energy transformation? Energy is absorbed because the product has more energy than the reactants have. Energy is absorbed because the product has less energy than the reactants have. Energy is lost because the product has more energy than the reactants have. Energy is lost because the product has less energy than the reactants have.

Energy is absorbed because the product has more energy than the reactants have.

Which energy changes are associated with a liquid freezing? Energy is released as potential energy increases. Energy is absorbed as potential energy increases. Energy is released as potential energy decreases. Energy is absorbed as potential energy decreases.

Energy is released as potential energy decreases.

Which statement is correct about the law of conservation of energy? Energy is created when water freezes. Energy is destroyed when sugar is burned. Energy stays inside molecules permanently. Energy is transferred when atoms are rearranged.

Energy is transferred when atoms are rearranged.

Which reaction is an example of heterogeneous catalysis? Ethene gas reacts with hydrogen gas by using a nickel catalyst. Hydrogen peroxide decomposes by using an aqueous iodide ion catalyst. Formic acid decomposes by using an acidic catalyst. Sulfur dioxide gas is converted to sulfur trioxide gas by using nitrogen chloride gas.

Ethene gas reacts with hydrogen gas by using a nickel catalyst.

A solid reactant is placed into a beaker of a warm water. The liquid vigorously bubbles as the solid dissolves into the solution. What will most likely happen if the temperature of the liquid is slightly reduced? More bubbles will be produced because the solution is becoming more concentrated. Fewer bubbles will be produced because of fewer collisions of reactant molecules. The solid will get smaller at a faster rate because of more collisions of reactant molecules. The solid will get larger at a slower rate because precipitate is coming out of the solution.

Fewer bubbles will be produced because of fewer collisions of reactant molecules.

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

An ice cube is placed on a kitchen counter. Which best describes heat flow in this situation? Heat flows from the ice to the counter, causing the molecules in the counter to move more quickly. Heat flows from the ice to the counter, causing the molecules in the counter to move more slowly. Heat flows from the counter to the ice, causing the molecules in the counter to move more quickly. Heat flows from the counter to the ice, causing the molecules in the counter to move more slowly.

Heat flows from the counter to the ice, causing the molecules in the counter to move more slowly.

Which statement best describes the use of a catalyst in a fuel cell? It reduces waste. It lowers energy requirements. It reduces toxic exhaust. It increases reaction rates.

It increases reaction rates.

What overall effect does adding a catalyst have on a chemical reaction? It increases pressure on the system. It increases reactant surface area. It lowers the activation energy that is needed. It lowers the concentration of reactants.

It lowers the activation energy that is needed.

What overall effect does adding a catalyst have on a chemical reaction? It slows the reaction. It speeds up the reaction. It reduces the concentration of products. It increases the concentration of reactants.

It speeds up the reaction.

Which statement describes how a basic coffee cup calorimeter works? It measures the mass of a substance given the specific heat and temperature of water in a cup of known size. It measures the density of a substance given the mass, specific heat, and temperature of water in a cup of known size. It uses the mass and specific heat of water along with a pressure gauge to measure the gain or loss of energy when a substance is added. It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.

It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.

Which units express specific heat capacity? J/°C, J/K, cal/°C, cal/K J/(gi°C), J/(giK), cal/(gi°C), cal/(giK) J, cal °C, K

J/(gi°C), J/(giK), cal/(gi°C), cal/(giK)

Which will cause an increase in the reaction rate between molecules? Molecules have strong internal bonding. Molecules collide more frequently. Electrons in the bonds remain in a meta-stable state. Electrons do not have enough energy to leave the bonds.

Molecules collide more frequently.

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.

Molecules in the cake are moving faster than molecules in the skin.

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.

Molecules in the pie move faster than molecules in the skin, so heat is transferred to the skin.

As gravity makes an object fall down toward the ground,_______ energy becomes kinetic energy.

POTENTIAL

During an endothermic phase change, what happens to the potential energy and the kinetic energy? Potential energy stays the same, and kinetic energy increases. Potential energy increases, and kinetic energy increases. Potential energy decreases, and kinetic energy decreases. Potential energy increases, and kinetic energy stays the same.

Potential energy increases, and kinetic energy stays the same.

Which statement best describes why specific heat capacity is often more useful than heat capacity for scientists when comparing two materials? Specific heat capacity is an intensive property and does not depend on sample size. Specific heat capacity is an extensive property and does not depend on sample size. Specific heat capacity is an intensive property and depends on the sample size. Specific heat capacity is an extensive property and depends on the sample size.

Specific heat capacity is an intensive property and does not depend on sample size.

The temperature of a gas is increased. Which statement best explains the effect that this has on the motion of gas particles? The average kinetic energy decreases, and the particles stop colliding. The average kinetic energy increases, and the particles stop colliding. The average kinetic energy decreases, and the particles collide less frequently. The average kinetic energy increases, and the particles collide more frequently.

The average kinetic energy increases, and the particles collide more frequently.

Two 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.

The gas molecules in both containers have the same average kinetic energy.

The temperature of a sample of liquid water changes from 50°C to 30°C. Which statement best explains the change that must happen at the molecular level? The molecules move more quickly and their average kinetic energy increases. The molecules move more slowly and their average kinetic energy decreases. The molecules move more quickly and their average kinetic energy decreases. The molecules move more slowly and their average kinetic energy increases.

The molecules move more slowly and their average kinetic energy decreases.

What is true about the solution process involved in an instant cold pack? The process is endothermic and has a negative enthalpy of solution. The process is exothermic and has a negative enthalpy of solution. The process is endothermic and has a positive enthalpy of solution. The process is exothermic and has a positive enthalpy of solution.

The process is endothermic and has a positive enthalpy of solution.

Which statement describes a system that consists of sugar crystals dissolving in water? The system becomes more ordered and has an increase in entropy. The system becomes more ordered and has a decrease in entropy. The system becomes more disordered and has an increase in entropy. The system becomes more disordered and has a decrease in entropy.

The system becomes more disordered and has an increase in entropy.

Which statement best describes the use of catalytic converters in automobiles? They decrease the rate of the reactions that produce harmful gases. They oxidize hydrocarbons to form less toxic gases. They combine the larger hydrocarbon molecules with smaller ones. They increase reaction temperature for cleaner burning.

They oxidize hydrocarbons to form less toxic gases.

What is the definition of entropy? a system that can exchange both matter and energy with its surroundings a measure of the overall disorder of a system a quantity that measures the overall spontaneity of a reaction a process that will proceed without continuous external influence

a measure of the overall disorder of a system

What scientific tool would be the most helpful when measuring the temperature of a substance that is undergoing a phase change? a spectrophotometer a thermometer the periodic table a scale

a thermometer

Which type of reaction is always spontaneous? an exothermic reaction that has an increase in disorder an exothermic reaction that has a decrease in disorder an endothermic reaction that has an increase in disorder an endothermic reaction that has a decrease in disorder

an exothermic reaction that has an increase in disorder

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

as an exothermic process because it releases heat

An arrow is fired at a target on a high wall. Which statement correctly describes the change in the energy of the arrow as it moves toward the target? A. The potential energy and kinetic energy remain the same. B. The potential energy decreases as kinetic energy increases. C. The kinetic energy decreases as potential energy increases. The kinetic energy remains at zero, but potential energy increases.

c: The kinetic energy decreases as potential energy increases

Which topic is commonly used to explain activation energy and how chemical reactions happen? reaction rate collision theory velocity distribution spontaneous reaction

collision theory

What would be the greatest difference in using an open ceramic coffee mug rather than an insulated mug with a lid as a calorimeter? increased evaporation of the water loss of gaseous reactants inability to contain liquids exchange of energy with the surroundings

exchange of energy with the surroundings

Which process involves an increase in entropy? crystallization of a solute from a solution ice melting into liquid water iodine vapor forming solid iodine condensing a gas into a liquid

ice melting into liquid water

An increase in temperature affects the reaction rate by decreasing the velocities of particles that collide in the reaction. increasing the number of molecules that have sufficient kinetic energy to react. increasing the number of molecules that have sufficient potential energy to react. decreasing the energy that particles need to overcome the energy activation barrier.

increasing the number of molecules that have sufficient kinetic energy to react.

In a chemical reaction occurring in an open beaker, the reactants have a mass of 10.0 g and contain 1000 J of energy. The products in the beaker contain a mass of 5.0 g and 500 J of energy. Which best explains the difference in energy and mass as reactants are converted to products? kinetic energy closed systems law of conservation electromagnetic energy

law of conservation

The heat capacity of a sample should be divided by which quantity to find the specific heat capacity? temperature in degrees Celsius temperature in kelvins volume in liters mass in grams

mass in grams

Which energy change best relates to a boulder that is rolling down the side of a hill? potential energy transforming into kinetic energy mechanical energy transforming into thermal energy potential energy transforming into electromagnetic energy mechanical energy transforming into electromagnetic energy

potential energy transforming into kinetic energy

Ben observes how quickly some dry wood is burning in a campfire. Which term best relates to Ben's observation? reaction rate activation energy collision theory spontaneous reaction

reaction rate

Which statement includes all the steps in the change that is associated with the enthalpy of solution? solute separation and mixing reaction of reactants to form products. solute and solvent mixing and then separating solute separation, solvent separation, and then mixing

solute separation, solvent separation, and then mixing

Which defines the average kinetic energy of a system's particles? density pressure temperature volume

temperature

Which statement defines the enthalpy of solution? the total number of particles in a solution the phase change from a solid to a liquid the difference in characteristics between reactants and products the change in energy when one substance dissolves in another

the change in energy when one substance dissolves in another

Which statement describes thermal energy? A. the energy that is associated with electric fields B. the energy that is stored in chemical bonds C. the energy that is associated with the pull of gravity D. the energy that is associated with temperature

the energy that is associated with temperature

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

the melting of ice

Which scientific tool is the most useful when trying to convert a known amount of grams of water to moles of water? a scale a thermometer the periodic table a spectrophotometer

the periodic table

Which statement defines specific heat capacity for a given sample? the temperature of a given sample the temperature that a given sample can withstand the quantity of heat that is required to raise the sample's temperature by 1°C (Kelvin) the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure

the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure

Which statement defines the heat capacity of a sample? the temperature of a given sample the temperature that a given sample can withstand the quantity of heat that is required to raise the sample's temperature by 1°C (or Kelvin) the quantity of heat that is required to raise 1 g of the sample by 1°C (or Kelvin) at a given pressure

the quantity of heat that is required to raise the sample's temperature by 1°C (or Kelvin)

Which process involves a decrease in entropy? burning natural gas water freezing into ice water evaporating on heating dry ice subliming

water freezing into ice