Chemistry Ch.3

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- Energy is a form of motion of particles inside an object and can be converted to thermal energy or heat - Energy can be classified as kinetic energy and potential energy. - Kinetic energy is determined by object's motion. - Potential energy is determined by object's composition and position.

Convert −218 °F to Kelvin.

134 K

Convert 28 °C to Kelvin.

301 K

Some homes that use baseboard heating use copper tubing. Hot water runs through and heats the copper tubing, which in turn heats aluminum fins. It is actually the aluminum fins that heat the air rising through the fins. How much energy would it take to heat a section of the copper tubing that weighs about 585.0 g , from 14.65 ∘C to 28.88 ∘C ? Copper has a specific heat of 0.3850 J/(g⋅∘C).

-4.11∘C Your answer −4.11−4.11 ∘C∘C was either rounded differently or used a different number of significant figures than required for this part. The temperature change of the 186.0 g g of water after it has released 3205 J J into the copper pipe is calculated by substituting the known values into the rearranged heat equation solving for ΔTΔT: ΔT = qm × SHΔT = qm × SH ΔT = −3205 J186.0 g × 4.184 J/(g ⋅ ∘C)ΔT = −3205 J186.0 g × 4.184 J/(g ⋅ ∘C) ΔT = ΔT = -4.118 ∘C ∘C The temperature change of the water is negative because heat is lost (it is transferred to the copper pipe) and the temperature of the water has cooled down. Water has a specific heat that is over 10 times that of copper. This allows copper tubing to be a great acceptor of heat for water traveling through it.

If the loss of 3500 kcal is equal to a loss of 1.0 lb, for the amount of exercise that Charles did for one week in Part A, how much weight, in pounds, did he lose?

0.56 The equality given, 3500 kcal/lb, is used as a conversion factor to calculate the weight loss that corresponds to the energy expenditure in Part A. The value of 3500 kcal should be in the denominator to allow the units of energy to cancel.

A 20 ounce bottle of soda provides a total of 300. Calories. How many kilojoules are in the soda?

1.26 x 10^3 kJ

Calculate the heat required to raise the temperature of 13.5 g of ethanol from 25.8 °C to 85.6 °C.

1.95x10^3 J

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Using the table below, determine the number of hours of running needed to burn off the kilocalories in this meal.

1.9h The calculation of the amount of time required to burn off the meal through running is 1460 kcal×1 h/750 kcal

Two units of measurement for energy are calories and joules. The measurement of 25.1 cal is the same amount of energy as ___________.

105 J

Convert this temperature to degrees Fahrenheit.

106.7 °F To convert a value from Celsius to Fahrenheit, substitute values into the appropriate equation: TF= =1.8(TC)+32 =1.8×(41.5∘C)+32 =106.7 ∘F

How many hours would Charles have to swim to lose 1.0 lb?

10h The calculation of the time needed to lose a pound while swimming is as follows: 1.0 lb×3500 kcal/1 lb×1 h/340 kcal

Calculate that temperature in degrees Fahrenheit.

116.6 °F Your answer 116.6116.6 ∘F∘F was either rounded differently or used a different number of significant figures than required for this part. The highest recorded body temperature in various units is 116 ∘F=46.5 ∘C=320 K116 ∘F=46.5 ∘C=320 K. Direct conversions of temperature involving degrees Celsius is possible. To convert between degrees Fahrenheit and kelvins, you must first convert one of the values to degrees Celsius.

The highest recorded body temperature that a person has survived is 320 KK. Calculate that temperature in degrees Fahrenheit.

117°F The highest recorded body temperature in various units is 116 ∘F=46.5 ∘C=320 K116 ∘F=46.5 ∘C=320 K. Direct conversions of temperature involving degrees Celsius is possible. To convert between degrees Fahrenheit and kelvins, you must first convert one of the values to degrees Celsius.

Calculate the energy needed to heat the cube of silver, with a volume of 20.0 cm3cm3 , from 12 ∘C∘C to 22 ∘C∘C. Refer to the tables.

118.02 Your answer 118.02ccal was either rounded differently or used a different number of significant figures than required for this part. The density of silver is 10.5 g/cm^3, so the cube of silver has a mass of 210 g . The relationship between heat and specific heat is heat=mass×temperature change×specific heatheat=mass×temperature change×specific heat where the temperature change is 10 ∘C and the specific heat of silver is 0.0562 cal/g⋅∘C .

The heat of vaporization for water is 540 cal/g. How many kilocalories are needed to change 22 g of liquid water to steam at 100 °C ?

12 kcal

The highest recorded temperature in Africa was 55 °C in Kebili, Tunisia, on July 7, 1931. Convert this temperature to Fahrenheit.

131 °F

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Determine the total kilocalories for the meal (rounding off to the tens place).

1460 kcal Your answer 1450kcal1450kcal was either rounded differently or used a different number of significant figures than required for this part. The total energy for the entire meal is the sum of 660 kcal+558 kcal+244 kcal660 kcal+558 kcal+244 kcal.

650. J is the same amount of energy as ________.

155 cal

Convert 320 °F to Celsius.

160 °C

Calculate the energy needed to heat the cube of copper, with a volume of 20.0 cm3cm3 , from 12 ∘C∘C to 22 ∘C∘C. Refer to the tables.

164.128 Your answer 164.128164.128 calcal was either rounded differently or used a different number of significant figures than required for this part. The calculation of the heat (qq) needed to raise the temperature of the copper cube by ΔTΔT is summarized as follows: q=mCu×ΔTCu×SHCu=(20.0 cm3×8.92 g1 cm3)×(10 ∘C)×(0.0920 cal/(g⋅∘C))

During one week, Charles swam for a total of 2.0 hh and walked for a total of 8.0 hh . If Charles expends 340 kcal/hkcal/h swimming and 160 kcal/hkcal/h walking, how many total kilocalories did he expend for one week?

1960 Your answer 1960 kcal was either rounded differently or used a different number of significant figures than required for this part. Charles expended 680 kcalof energy swimming and 1300 kcal of energy walking.

Convert the boiling point of water, 100.0 °C, into °F by using the correct equation. TF = 1.8(Tc) + 32 TK= Tc + 273 Remember to select an answer with the correct number of significant figures.

212.0 °F

A serving of fish contains 50 g protein and 4 g of fat. If protein has a caloric value of 4 kcal/g and fat has 9 kcal/g, how many kcal are in the serving? Round off the energy value for each food group to the tens place.

240 kcal

One cup of kidney beans contains 15g of protein, 1g of fat, and 42g of carbohydrate. How many kilocalories, to two significant figures, does this sample contain? (The caloric values are: 4 kcal/for carbohydrates, 9 kcal/g for fat, and 4 kcal/g for proteins. Round off the energy value of each food group to the tens place.)

240 kcal

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Using the table on the left, calculate the total kilocalories for protein (rounding off the kilocalories to the tens place).

240 kcal The meal has 61 gg of proteins, and proteins provide energy at 4 kcal/gkcal/g (i.e., the conversion factor). Multiplying the mass of proteins by the conversion factor allows grams to cancel and yields the energy from proteins in kilocalories.

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Using the table below, determine the number of hours of sleeping needed to burn off the kilocalories in this meal.

24h The body uses energy while we sleep for various activities, including pumping blood, making new cells, and other types of biological maintenance. Daily activities are taken into account when calculating the daily recommended values, which depend on the person's age, weight, and level of physical activity.

The heat equation, as given in the introduction, can also be rearranged to calculate the mass or temperature change for a substance. Follow the same steps used to calculate the quantity of heat gained or lost, but when you solve the equation, the term for mass or temperature change must be isolated on one side of the equation. What mass, in grams, of aluminum fins could 3205 J J of energy heat from 14.65 ∘C ∘C to 28.88 ∘C ∘C ? Aluminum has a specific heat of 0.897 J/(g⋅∘C)J/(g⋅∘C).

251.1 Your answer 251.1251.1 gg was either rounded differently or used a different number of significant figures than required for this part. The mass of the aluminum fins that could be heated by 3205 J J from 14.65 ∘C ∘C to 28.88 ∘C ∘C (which is equivalent to heating from 58.37 ∘F ∘F to 83.98 ∘F ∘F ) is calculated by substituting the known values into the rearranged heat equation solving for mass: m = qΔT × SHm = qΔT × SH m = 3205 J14.23 ∘C × 0.897 J/(g⋅∘C)m = 3205 J14.23 ∘C × 0.897 J/(g⋅∘C) m = m = 251 g

If the heat of fusion for water is 80. cal/g, how many calories are needed to melt 45.0 g of ice at 0 °C?

3.6 x 10^3 cal

Changes in state are called phase changes. A phase change is a change from one physical state (gas, liquid, or solid) to another. The amount of energy necessary to melt 1 mole of any solid is called its enthalpy of fusion. The amount of energy necessary to vaporize 1 mole of any substance is called its enthalpy of vaporization. The enthalpy of vaporization of liquid isopropyl alcohol is 45 kJ/mol. Calculate the energy required to vaporize 39.5 g of this compound.

30. kJ

A person uses 730 kcalkcal on a long hike. Calculate the energy used for the hike in each of the following energy units. What is the energy in joules?

3054320 J Your answer 30543203054320 JJ was either rounded differently or used a different number of significant figures than required for this part. Given that 1 cal=4.184 J1 cal=4.184 J, you could add a metric prefix to both sides to establish that 1 kcal=4.184 kJ1 kcal=4.184 kJ. The value of the energy in joules is 1000 times greater than the value of energy in kilojoules.

Some homes that use baseboard heating use copper tubing. Hot water runs through and heats the copper tubing, which in turn heats aluminum fins. It is actually the aluminum fins that heat the air rising through the fins. How much energy would it take to heat a section of the copper tubing that weighs about 585.0 g g , from 14.65 ∘C ∘C to 28.88 ∘C ∘C ? Copper has a specific heat of 0.3850 J/(g⋅∘C)J/(g⋅∘C).

3205J Important: If you use this answer in later parts, use the full unrounded value in your calculations. The amount of heat absorbed by the copper pipe (with a mass of 585.0 g g ) to raise it from 14.65 ∘C ∘C to 28.88 ∘C ∘C (which is equivalent to heating from 58.37 ∘F ∘F to 83.98 ∘F ∘F ) is 3205 J J . This is calculated by substituting the known values into the heat equation and solving accordingly. q = 585.0 g × 14.23 ∘C × 0.385 J/(g⋅∘C) q=3205 J The value is reported to four significant digits to prevent rounding errors in future calculations. Since heat is absorbed, the energy change is positive (endothermic). When heat is released, such as when the copper pipe cools, the energy change is negative (exothermic).

For lunch, a patient consumed 3 ozoz of beef, 3 ozoz of broccoli, 1 medium banana, and 1 cup of carrots (see the table below). How many kilocalories did the patient obtain from the lunch?

410 kcal For each item the patient ate for lunch, look up the number of kilocalories in the table, and then sum all of the energy values for those lunch items. The total number of kilocalories is the sum of 220 kcal+30 kcal+110 kcal+50 kcal220 kcal+30 kcal+110 kcal+50 kcal.

A person with hyperthermia has a temperature of 107 ∘F∘F. What does this read on a Celsius thermometer?

42°C The equation TF=1.8(TC)+32TF=1.8(TC)+32 can be rearranged to solve for the temperature in degrees Celsius, TCTC. The conversion to degrees Celsius is TC=TF−321.8=107 ∘F−321.8

Calculate that temperature in degrees Celsius.

46.5 °C Your answer 46.5 ∘C∘C was either rounded differently or used a different number of significant figures than required for this part. The direct conversion from kelvins to degrees Celsius uses the following equation: TC=TK−273

The highest recorded body temperature that a person has survived is 320 KK. Calculate that temperature in degrees Celsius.

47°C The direct conversion from kelvins to degrees Celsius uses the following equation: TC=TK−273

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Using the table on the left, calculate the total kilocalories for fat (rounding off the kilocalories to the tens place).

576 kcal Your answer 576kcal was either rounded differently or used a different number of significant figures than required for this part. The meal has 62 gg of fats, and fats provide energy at 9 kcal/gkcal/g (i.e., the conversion factor). Multiplying the mass of fat by the conversion factor allows grams to cancel and yields the energy from fat in kilocalories.

A 70.0-kgkg person had a quarter-pound cheeseburger, french fries, and a chocolate shake. Using the table on the left, calculate the total kilocalories for carbohydrates (rounding off the kilocalories to the tens place).

676 kcal Your answer 676kcal was either rounded differently or used a different number of significant figures than required for this part. The meal has 165 gg of carbohydrates, and carbohydrates provide energy at 4 kcal/gkcal/g (i.e., the conversion factor). Multiplying the mass of carbohydrates by the conversion factor allows grams to cancel and yields the energy from the carbohydrates in kilocalories.

The temperature of liquid nitrogen is -196 C. What is the corresponding reading on the Kelvin scale?

77k

A 143-g sample of mercury is at an initial temperature of 25 °C. If 1067 joules of heat are applied to the sample, what is the final temperature of the mercury? The specific heat capacity of mercury is 0.14 J/(g∙ °C).

78 °C

Water is heated to 175 ∘F∘F. What is the temperature of the hot water in degrees Celsius?

79°F The equation TF=1.8(TC)+32TF=1.8(TC)+32 can be rearranged to solve for the temperature in degrees Celsius, TCTC. The conversion to degrees Celsius is TC=TF−32/1.8=175∘F−32/1.8

Changes in state are called phase changes. A phase change is a change from one physical state (gas, liquid, or solid) to another. The amount of energy necessary to melt 1 mole of any solid is called its enthalpy of fusion. The amount of energy necessary to vaporize 1 mole of any substance is called its enthalpy of vaporization. The enthalpy of fusion of ice is 6.02 kJ/mol. Calculate the energy required to melt 25.9 g of ice.

8.67 kJ

How many calories are required to increase the temperature of 13 g of alcohol from 11 °C to 23 °C? The specific heat of alcohol is 0.59 cal/g °C.

92 cal

Chemistry involves two basic types of changes: physical and chemical. Associated with these changes are physical properties and chemical properties. Physical properties are characteristics used to describe the appearance of a substance. This includes observations like the state, color, size, and shape of matter. Chemical properties are characteristics used to describe the chemical behavior of a substance. This includes observations like reactivity, as well as the inability to react. Which of the following describes a physical property of copper metal?

Copper metal is pulled into thin wires.

Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the mixed substances can be present in any ratio. There are two types of mixtures: homogeneous and heterogeneous. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Because of this, homogeneous mixtures look identical throughout the mixture to our eyes, as we cannot physically see the presence of more than one substance due to the uniformity. In terms of heterogeneous mixtures, we are able to see a physical boundary between different substances within the mixture, indicating the presence of more than one substance. Which of the following is an example of a homogenous mixture?

Cranberry juice

Classify the following phase changes as processes that require the input of energy, or as processes that have a net output of energy.

Exothermic reaction are characterized by the output, or release, of energy. Endothermic reactions are characterized by the input, or absorption, of energy. Return to Assignment

Matter is defined as anything that has mass and occupies space. Matter exists in three different states: solids, liquids, and gases. Because solids, liquids, and gases all have a well-defined mass, the differences in the state of matter can be determined by their shape and their volume. On the micro-level, or the atomic level, the particles in the three states of matter are also arranged differently, which helps to contribute to their unique properties. In the solid state, the particles are well organized and very close together. This results in the solid state having a fixed shape and fixed volume. In the liquid state, the particles move slowly, move in random directions, and are close together, due to their attractions. This results in the liquid state having a well-defined volume but taking on the shape of the container. In the gas state, the particles move quickly and in random directions. As a result, the particles are far apart and fill the container. Therefore, the volume and shape of a gas are determined by the container. The figure given below depicts two of the three states of matter on the micro-level. Which states of matter are shown?

Gas and liquid

Chemistry involves two basic types of changes: physical and chemical. Associated with these changes are physical properties and chemical properties. Physical properties are characteristics used to describe the appearance of a substance. This includes observations like the state, color, size, and shape of matter. Chemical properties are characteristics used to describe the chemical behavior of a substance. This includes observations like reactivity as well as the inability to react. Which of the following describes a chemical property of gasoline?

Gasoline ignites easily in air.

Which of the following is an example of a physical change?

Grinding coffee beans

Chemistry involves two basic types of changes: physical and chemical. Physical changes are changes that do not require a change in the chemical identity of a substance. They often involve changes in the state of matter or the creation or separation of a mixture. Chemical changes are changes that involve a change in the chemical identity of a substance. In other words, a new chemical or substance is created through a chemical change. A chemical change is also thought of as a chemical reaction. Which of the following is a physical change?

Grinding peppercorns into pepper flakes

There are two types of pure substances: elements and compounds. An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. The Periodic Table of the Elements lists all of the known elements in the universe. A compound is a form of matter that contains two or more different elements, bonded together in a fixed ratio. For instance, water is a compound as it always consists of the elements hydrogen and oxygen. More specifically, water contains two hydrogen atoms bonded to one oxygen atom. There are two types of impure substances or mixtures: homogeneous and heterogeneous. Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Is chicken noodle soup an element, a compound, a homogeneous mixture, or a heterogeneous mixture?

Heterogeneous mixture

There are two types of pure substances: elements and compounds. An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. The Periodic Table of the Elements lists all of the known elements in the universe. A compound is a form of matter that contains two or more different elements, bonded together in a fixed ratio. For instance, water is a compound as it always consists of the elements hydrogen and oxygen. More specifically, water contains two hydrogen atoms bonded to one oxygen atom. There are two types of impure substances or mixtures: homogeneous and heterogeneous. Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Is mouthwash an element, a compound, a homogeneous mixture, or a heterogeneous mixture?

Homogeneous mixture

There are two types of pure substances: elements and compounds. An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. The Periodic Table of the Elements lists all of the known elements in the universe. A compound is a form of matter that contains two or more different elements, bonded together in a fixed ratio. For instance, water is a compound as it always consists of the elements hydrogen and oxygen. More specifically, water contains two hydrogen atoms bonded to one oxygen atom. There are two types of impure substances or mixtures: homogeneous and heterogeneous. Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Is vegetable oil an element, a compound, a homogeneous mixture, or a heterogeneous mixture?

Homogeneous mixture

Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. There are two types of mixtures: homogeneous and heterogeneous. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Because of this, homogeneous mixtures look identical throughout the mixture to our eyes, as we cannot physically see the presence of more than one substance due to the uniformity. In terms of heterogeneous mixtures, we are able to see a physical boundary between different substances within the mixture, indicating the presence of more than one substance. Which of the following is an example of a heterogeneous mixture?

Lemonade with pulp

Matter is defined as anything that has mass and occupies space. Matter exists in three different states: solids, liquids, and gases. Because solids, liquids, and gases all have a well-defined mass, the differences in the state of matter can be determined by their shape and their volume. On the micro-level, or the atomic level, the particles in the three states of matter are also arranged differently, which helps to contribute to their unique properties. In the solid state, the particles are well organized and very close together. This results in the solid state having a fixed shape and fixed volume. In the liquid state, the particles move slowly, move in random directions, and are close together, due to their attractions. This results in the liquid state having a well-defined volume but taking on the shape of the container. In the gas state, the particles move quickly and in random directions. As a result, the particles are far apart and fill the container. Therefore, the volume and shape of a gas are determined by the container. The figure given below depicts one of the three states of matter on the micro-level. Which state of matter is shown?

Liquid

Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. There are two types of mixtures: homogeneous and heterogeneous. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Because of this, homogeneous mixtures look identical throughout the mixture to our eyes, as we cannot physically see the presence of more than one substance due to the uniformity. In terms of heterogeneous mixtures, we are able to see a physical boundary between different substances within the mixture, indicating the presence of more than one substance. Which of the following is an example of a homogenous mixture?

Low-fat milk (1%)

Chemistry involves two basic types of changes: physical and chemical. Physical changes are changes that do not require a change in the chemical identity of a substance. They often involve changes in the state of matter or the creation or separation of a mixture. Chemical changes are changes that involve a change in the chemical identity of a substance. In other words, a new chemical or substance is created through a chemical change. A chemical change is also thought of as a chemical reaction. Which of the following is an example of a physical change?

Melting snow

Chemistry involves two basic types of changes: physical and chemical. Physical changes are changes that do not require a change in the chemical identity of a substance. They often involve changes in the state of matter or the creation or separation of a mixture. Chemical changes are changes that involve a change in the chemical identity of a substance. In other words, a new chemical or substance is created through a chemical change. A chemical change is also thought of as a chemical reaction. Which of the following is a physical change?

Melting solid gold to pour into a jewelry mold

In the video, you can see that as heat is applied to a solid, it is converted into the liquid phase and then into the gas phase. This process can be studied by plotting the graph of temperature verses the time during which heat is applied to the system. Identify the states of matter and the processes that occur at each of the positions on the graph.

Point a is the melting point of the solid. The line ab represents the melting process of the solid, during which the solid and liquid are in equilibrium. Point c is the boiling point of the liquid. The line cd represents the boiling process of the liquid, during which the liquid and gas are in equilibrium.

The following graph is a heating curve for chloroform, a solvent for fats, oils, and waxes. What is the approximate melting point and boiling point of chloroform?

The melting point is about -60 °C and the boiling point is about 60 °C.

A hot-water bottle contains 727 g of water at 63 ∘C. If the liquid water cools to body temperature (37 ∘C), how many kilojoules of heat could be transferred to sore muscles?

The problem is asking for the kilojoules transferred, so the specific heat value of liquid that is needed is 4.184 J/(g⋅∘C)J/(g⋅∘C). The final answer must be converted into the unit kilojoules from joules, since the specific heat units are in joules. In summary then joulestransferred===mass×ΔT×specificheat727 g×(63 ∘C−37 ∘C)×4.184J g⋅ ∘C7.9×104 Jjoulestransferred=mass×ΔT×specificheat=727 g×(63 ∘C−37 ∘C)×4.184J /g⋅ ∘C=7.9×104 J and converting to kilojoules gives kilojoules transferred=7.9×104 J×1kJ/1000 J=7.9×101 kJ

There are two types of pure substances: elements and compounds. An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. The Periodic Table of the Elements lists all of the known elements in the universe. A compound is a form of matter that contains two or more different elements, bonded together in a fixed ratio. For instance, water is a compound as it always consists of the elements hydrogen and oxygen. More specifically, water contains two hydrogen atoms bonded to one oxygen atom. There are two types of impure substances or mixtures: homogeneous and heterogeneous. Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Is propane, C3H8, an element, a compound, a homogeneous mixture, or a heterogeneous mixture?

compound

Which of the following is a physical change?

ice melts

Which one of the following properties describes a liquid?

particles are close together and move randomly

Food releases heat energy as it is broken down in our body, or metabolized. Food energy is an example of_________.

potential energy

The energy stored in molecules is __________.

potential energy

As a leaf falls from a tree, its _____.

potential energy decreases and its kinetic energy increases

In which of the following would the particles move most rapidly?

steam at 110 °C

A burn from steam at 100 °C is expected to be more severe than a burn from boiling water at 100°C because

the steam will give off a large amount of heat as it condenses.

Convert 9.5 kcalkcal to its value in calories.

9.5×103 cal Value - 9500 Units - cal The prefix kilo represents a value of 1000. Therefore, 1 kilocalorie = 1000 calories. The conversion factor is written so that the unwanted unit of kcalkcal cancels out and the desired unit of calcal remains: number of calories=9.5 kcal×1000cal / 1 kcal=9500 cal

During extreme hypothermia, a boy's temperature dropped to 32.8 ∘C∘C. What was his temperature in degrees Fahrenheit?

91°F Your answer 9090 ∘F∘F was either rounded differently or used a different number of significant figures than required for this part. The boy's temperature is converted to degrees Fahrenheit using the following equation:TF=1.8(32.8∘C)+32TF=1.8(32.8∘C)+32.

The energy of motion is referred to as __________.

kinetic energy

Which of the following would NOT be a physical change?

Burning gasoline in a car

An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. Elements are pure substances, as they consist of only one type of matter, in a fixed composition. The Periodic Table of the Elements lists all of the known elements in the universe. Which of the following is an element?

Chromium, Cr

Chemistry involves two basic types of changes: physical and chemical. Physical changes are changes that do not require a change in the chemical identity of a substance. They often involve changes in the state of matter or the creation or separation of a mixture. Chemical changes are changes that involve a change in the chemical identity of a substance. In other words, a new chemical or substance is created through a chemical change. A chemical change is also thought of as a chemical reaction. Which of the following is a physical change?

Dissolving sugar in water

In which of the following would the particles move most rapidly?

steam at 110C

There are two types of pure substances: elements and compounds. An element is the simplest form of matter that retains its own unique properties, which are different from all other elements. The Periodic Table of the Elements lists all of the known elements in the universe. A compound is a form of matter that contains two or more different elements, bonded together in a fixed ratio. For instance, water is a compound as it always consists of the elements hydrogen and oxygen. More specifically, water contains two hydrogen atoms bonded to one oxygen atom. There are two types of impure substances or mixtures: homogeneous and heterogeneous. Mixtures involve two or more substances that are physically mixed or intermingled. However, these substances are not chemically bonded together. Therefore, the substances can be present in any ratio. A homogeneous mixture has a uniform composition whereas a heterogeneous mixture does not have a uniform composition. Is mercury, Hg, an element, a compound, a homogeneous mixture, or a heterogeneous mixture?

Element

How are heat and kinetic energy related?

Heat energy is the energy associated with the kinetic energy of the particles in a substance.

Matter is defined as anything that has mass and occupies space. Matter exists in three different states: solids, liquids, and gases. Because solids, liquids, and gases all have a well-defined mass, the differences in the state of matter can be determined by their shape and their volume. Which of the following descriptions is used to describe the solid state?

Matter in this state has a definite shape and definite volume.

Matter is defined as anything that has mass and occupies space. Matter exists in three different states: solids, liquids, and gases. Because solids, liquids, and gases all have a well-defined mass, the differences in the state of matter can be determined by their shape and their volume. Which of the following descriptions is used to describe the liquid state?

Matter in this state has a definite volume, and the shape is determined by the container.

Because high fevers can cause convulsions in children, the doctor wants to be called if a child's temperature goes over 40.0 ∘C∘C. Should the doctor be called if a child has a temperature of 103 ∘F∘F?

No, there is no need to phone the doctor. A temperature of 40.0 ∘C∘C on the Fahrenheit scale is 104 ∘F∘F, but the child's temperature is below this value.

Rank from highest to lowest. To rank items as equivalent, overlap them.

Phase changes always occur with a change in the average amount of heat in a system. Heat, which is a measure of energy, either is absorbed by the material during a phase change or is released by the material during the phase change. However, although the heat content of the material changes, the temperature does not change during a phase change.

Black ice is a thin layer of water on a sidewalk or road that has frozen after the temperature has dropped below freezing. It is called black ice because the ice is nearly invisible, especially when driving in a car at night. Which of the following statements is true?

The formation of black ice is an example of a physical change.

You happen to be visiting Northern California and you are driving by Suisun Bay, a notorious graveyard for old ships. You notice that all of these ships appear to be rusting away. Which of the following statements is true?

The rusting of the metal is a chemical change.

Matter is defined as anything that has mass and occupies space. Matter exists in three different states: solids, liquids, and gases. Because solids, liquids, and gases all have a well-defined mass, the differences in the state of matter can be determined by their shape and their volume. Which of the following descriptions describes the gas state?

The shape and volume are determined by the container.

Chemistry involves two basic types of changes: physical and chemical. Physical changes are changes that do not require a change in the chemical identity of a substance. They often involve changes in the state of matter or the creation or separation of a mixture. Chemical changes are changes that involve a change in the chemical identity of a substance. In other words, a new chemical or substance is created through a chemical change. A chemical change is also thought of as a chemical reaction. Which of the following is a chemical change?

Burning gasoline in your car

Which of the following is a chemical change?

Burning sugar

Convert 393 JJ to its value in kilojoules.

Value - 0.393 Units - kJ The prefix kilo represents a value of 1000. Therefore, 1 kilojoule = 1000 joules. The conversion factor is written so that the unwanted unit of JJ cancels out and the desired unit of kJkJ remains: number of kilojoules=393 J×1kJ/1000 J

Convert 2870 calcal to its value in kilojoules.

Value - 12.00808 Units - kJ Your answer 12.00808kJ12.00808kJ was either rounded differently or used a different number of significant figures than required for this part. The equality between calorie and joule is used in this problem: 4.184 J=1 cal4.184 J=1 cal. Then the equality 1 kilojoule = 1000 joules is used. Use these equalities to create conversion factors written such that the unwanted units cancel out and the desired units remain: number of kilojoules=2870 cal×4.184 J/ 1 cal×1kJ/1000 J

Convert 3.30 kcal to its value in joules.

Value - 13807.2 Units - J Your answer 13807.2J13807.2J was either rounded differently or used a different number of significant figures than required for this part. First the equality 1 kilocalorie = 1000 calories is used, and then the equality 1 cal=4.184 J1 cal=4.184 J is used. Use these equalities to create conversion factors written such that the unwanted units cancel out and the desired units remain: number of joules=3.30 kcal×1000 cal/1 kcal×4.184J/1 cal

The specific heat capacity for a substance is the amount of heat needed to raise the temperature of 1 g of a substance by 1 °C. It is measured in units of J/( g∙°C) Calculate the specific heat capacity for a 22.7-g sample of lead that absorbs 237 J when its temperature increases from 29.8 °C to 95.6 °C.

0.159J over g∙°C

If the heat of vaporization for water is 540 cal/g, how many kilocalories are released when 5.00 g of steam is converted to liquid at 100 °C?

2.7 kcal

How many hours would Charles have to walk to lose 1.0 lblb?

22h This equates to walking for approximately 3 hh every day for a week. Some of this time could be saved by incorporating a more rigorous activity during the week.

675 cal is the same amount of energy as __________.

2820j

13.2 kJ is the same amount of energy as ________.

3.15 kcal

A person uses 730 kcalkcal on a long hike. Calculate the energy used for the hike in each of the following energy units. What is the energy in kilojoules?

3054.32 kJ Your answer 3054.323054.32 kJkJ was either rounded differently or used a different number of significant figures than required for this part. The energy can be directly converted from kilocalories to kilojoules as follows: 730 kcal×4.184 kJ1 kcal730 kcal×4.184 kJ1 kcal It would also be valid to calculate it without the modified conversion factor, as shown here: 730 kcal×1000 cal/1 kcal×4.184 J/1 cal×1 kJ/1000 J

The highest recorded body temperature that a person has survived is 46.5 °C. What will be the temperature in degrees Fahrenheit and in kelvins?

320 °F and 320. K

Which of the following would not be a physical change?

burning gasoline in a lawnmower

Convert the normal body temperature, 98.7 °F, into °C by using the correct equation.

37.1 °C

Convert 215 °F to Kelvin.

375 K

Alexandra decides to climb Mt. Krumpett, which is 5000 mm high. She determines that this will require a total of 1800 kcalkcal of energy for the trip. For her food supply, she decides to take nutrition bars. The label states that each bar contains 50 gg of carbohydrates, 10 gg of fat, and 40 gg of protein. How many nutrition bars should Alexandra pack?

4 bars

Identify the temperature reading on the Celsius thermometer.

41.5 °C The tick marks on the thermometer are to the ones place, as the larger marks are to the tens place. With one digit of estimation, the temperature on the Celsius thermometer is 41.5 ∘C∘C.

If the temperature is 20. °C, what is the corresponding temperature on the Fahrenheit scale?

68 °F

How many calories are required to raise the temperature of a 150. g sample of gold from 25 0C to 175 0C? The specific heat of gold is 0.0308 cal/g 0C.

693 cal

The temperature of liquid nitrogen is -196 °C. What is the corresponding reading on the Kelvin scale?

77 K

In a gas, the distance between the particles is ________.

very large relative to the size of the molecules

Which of the following is an example of potential energy?

water stored in a reservoir

Convert −86 °F to Celsius.

−66 °C