2A2 Relationships between Energy and Matter Flashcards
Explore how energy and matter shape the organization of matter, distinguish chemical and physical properties, and demonstrate conservation in processes, applying thermodynamic principles and models to explain these interactions.
What is matter?
Anything that has mass and takes up space.
What are the 4 states of matter?
- Solid
- Liquid
- Gas
- Plasma
Define:
compound
Two or more elements chemically combined.
These compounds can have different properties compared to their constitutuent elements. Examples of compounds include water (H~2~O) or carbon dioxide CO~2~.
True or False:
Matter can be classified by its physical and chemical properties.
True
Physical properties can be observed without changing the substance’s identity (e.g., density), while chemical properties describe how a substance reacts in chemical processes (e.g., reactivity with oxygen).
Define:
Mixture
A combination of two or more substances that are not chemically bonded.
Mixtures can be either homogeneous (uniform composition) or heterogeneous (non-uniform composition).
True or False:
A homogeneous mixture has a uniform composition throughout.
True
In homogeneous mixtures, the components are evenly distributed, like in air or saltwater.
What is the main characteristic of a heterogeneous mixture?
The components are not evenly distributed.
Examples of heterogeneous mixtures include salad or granite, where you can distinguish the individual components.
What is a solution?
A homogeneous mixture where one substance dissolves in another.
Solutions are typically liquid, but can also be gases or solids (e.g., alloys). The solute dissolves in the solvent.
Fill in the blank:
A solution consists of a _______ dissolved in a _______.
solute; solvent
In a solution, the solute is the substance being dissolved, while the solvent is the substance doing the dissolving.
True or False:
Colloids are mixtures where the particles are large enough to settle.
False
In these mixtures, the particles are small enough to remain suspended but too large to dissolve, like in milk or fog.
Fill in the blank:
The particles in a _______ mixture can be easily seen and separated.
heterogeneous
Heterogeneous mixtures, like a salad or trail mix, allow the individual components to be visually distinguished and physically separated.
What type of mixture is milk?
Colloid
Milk is a colloid because fat droplets are dispersed in water and remain suspended.
True or False:
Chemical properties can be observed directly without a chemical reaction.
False
Chemical properties, such as reactivity or flammability, can only be observed when a substance undergoes a chemical change or reaction.
What happens to matter during a physical change?
It changes form but not composition.
In physical changes, the substance’s identity remains the same; only the appearance or phase changes.
For example, ice melting into water still consists of H2O.
What is corrosion?
A chemical reaction that breaks down metals.
A common example is the rusting of iron, where iron reacts with oxygen and water to form iron oxide, weakening the material.
True or False:
Density is a chemical property.
False
Density is a physical property because it can be measured without changing the substance’s chemical identity.
For example, the density of water can be measured without changing its chemical identity.
Fill in the blank:
The Triple Point refers to the condition where a substance exists in all three states of matter at once, under specific conditions of _______ and _______.
temperature, pressure
This refers to the unique set of conditions where solid, liquid, and gas phases coexist in equilibrium.
For water, this occurs at 0.01°C and a pressure of 611.2 pascals.
What is a chemical change?
A reaction that forms new substances.
Chemical changes, like burning wood, produce new materials that have different properties from the original substance.
What is a phase change?
The transformation of a substance from one state of matter to another.
Examples of phase changes include melting (solid to liquid), freezing (liquid to solid), and vaporization (liquid to gas).
Fill in the blank:
When milk is left out at room temperature, it sours and becomes thicker due to the growth of bacteria, which produces lactic acid. The souring of milk is an example of a ______ change.
chemical
The souring of milk is a chemical change because bacteria ferment lactose into lactic acid, which alters the milk proteins, causing them to denature and coagulate. This thickens the milk and forms new substances.
What is the opposite of melting?
Freezing
Freezing is the process where a liquid loses heat and turns into a solid. For example, water freezes into ice when the temperature drops below 0°C.
Fill in the blank:
When dry ice (solid carbon dioxide) is left at room temperature, it changes directly from a solid to a gas without becoming a liquid. This process is called ______.
sublimation
Dry ice undergoes sublimation, where a solid changes directly into a gas without becoming a liquid.
What is vaporization?
The process in which a liquid turns into a gas by gaining energy.
Vaporization can occur through boiling (when a liquid is heated to its boiling point) or evaporation (when molecules at the surface of a liquid gain enough energy to escape into the air).
Define:
Condensation
The process where a gas turns into a liquid upon cooling.
For example, water vapor in the air condenses into liquid water on a cold surface, like a glass of ice-cold water.
What are the characteristics of a solid?
Has a definite shape and volume.
In solids, particles are tightly packed and vibrate in place, keeping the shape fixed.
What are the characteristics of a liquid?
Has a definite volume but no definite shape.
Liquids can flow and take the shape of their container, as the particles are not as tightly bound as in solids.
What phase change occurs when a gas turns directly into a solid without passing through the liquid phase?
Deposition
Deposition is the phase transition where a gas turns directly into a solid, such as when water vapor forms frost on a cold surface.
What does the Law of Conservation state?
Matter cannot be created or destroyed, only transformed.
In both physical and chemical changes, the total mass remains constant, even if the form changes.
Fill in the blank:
A common example of a ______ change is rusting.
chemical
Rusting is a chemical change where iron reacts with oxygen to form iron oxide, a new substance.
What is energy transformation?
Changing one form of energy to another.
For example, in a light bulb, electrical energy is transformed into light and thermal energy.
What are the most common types of energy?
- Chemical energy
- Mechanical energy
- Thermal energy
- Nuclear energy
- Electromagnetic energy
- Electrical energy
These energies can be either potential (stored) or kinetic (in motion).
What is kinetic energy?
Energy of motion
Kinetic energy depends on the mass and speed of an object, such as a moving car or a flying bird.
What is potential energy?
Stored energy
Potential energy can be gravitational (due to position) or chemical (due to bonds), like the energy stored in food or a raised object.
True or False:
Kinetic energy increases with speed.
True
The faster an object moves, the more kinetic energy it has, as kinetic energy is proportional to the square of the speed.
What happens when chemical energy in food is converted to mechanical energy?
The body uses the energy to perform movement.
In biological systems, chemical energy from food is converted to mechanical energy to power muscles.
How can electrical energy be transformed in a circuit?
It can transform into light, heat, or mechanical energy.
For example, in a motor, electrical energy is converted to mechanical (kinetic) energy to move a fan or other device.
True or False:
Kinetic energy includes chemical energy.
False
Chemical energy is a form of potential energy stored in chemical bonds, not kinetic energy.
Fill in the blank:
A roller coaster at the top of a hill has energy due to its height. This is an example of ________ energy.
potential
The roller coaster has gravitational potential energy at the top of the hill, which is converted to kinetic energy as it descends.
Fill in the blank:
A car speeding down a highway has energy due to its motion. This is an example of _______ energy.
kinetic
The car has kinetic energy because it is in motion, and its speed and mass determine the amount of energy it possesses.
Define:
Heat
Energy from particle movement or vibrations.
Heat results from the kinetic energy of atoms or molecules moving or vibrating. It can be transferred through conduction, convection, or radiation.
True or False:
Heat is always transferred from a cooler object to a warmer one.
False
Heat always transfers from hot to cold until equilibrium is reached (i.e., the temperatures balance).
Define:
Temperature
A measurement of the average kinetic energy of particles.
Temperature quantifies the heat in a system, usually in Celsius, Kelvin, or Fahrenheit, and reflects how fast the particles move.
What is the boiling point of water in Celsius?
100°C
Water boils at 100°C at 1 atmosphere of pressure. Boiling points can change with altitude or pressure.
What is the freezing point of water in Kelvin?
273.15 degrees Kelvin
Freezing occurs at 0°C or 32°F, and this is equivalent to 273.15 K on the Kelvin scale.
Define:
Absolute zero
The point where particle motion stops, at -273.15°C or 0K.
Absolute zero is theoretically the lowest temperature possible, where molecular motion ceases.
What are the three modes of heat transfer?
- Conduction
- Convection
- Radiation
Heat moves from hot to cold through direct contact (conduction), fluid movement (convection), or electromagnetic waves (radiation).
What is the study of energy transfer and its effects on matter called?
Thermodynamics
Thermodynamics deals with concepts like heat, work, and energy, such as the efficiency of engines or refrigerators.
What does the first law of thermodynamics state?
Energy cannot be created or destroyed, only transferred or transformed.
This law explains the conservation of energy in closed systems, such as in heat engines or chemical reactions.
True or False:
Heat flows from hot to cold, and systems tend to increase in disorder (entropy), as stated in the second law of thermodynamics.
True
This law means that energy transformations are never fully efficient, and natural processes always lead to increased entropy.
Fill in the blank:
The third law of thermodynamics states that as temperature approaches absolute zero, the ________ of a system approaches a constant value.
entropy
At absolute zero (0 K), a perfect crystal would have zero entropy, as the system reaches its lowest energy state.
Define:
Specific heat
The amount of energy required to change a substance’s temperature by 1°C per unit mass.
Specific heat varies by material; for example, water has a high specific heat, meaning it resists temperature changes.
What is convection?
Heat transfer through the movement of fluids.
A pot of boiling water demonstrates convection as water molecules expand and circulate.
Fill in the blank:
________ is the transfer of heat through a solid without the movement of the substance itself.
Conduction
In conduction, heat is transferred through direct contact, typically in solids, where particles vibrate and pass energy to neighboring particles.
True or False:
Water has a low specific heat.
False
Water has a high specific heat, meaning it absorbs and retains heat well compared to other substances.
How is heat transferred through radiation?
Through electromagnetic waves.
Radiation transfers energy in the form of electromagnetic waves, such as the heat from the sun or a microwave.
What is a heat engine?
A device that converts thermal energy into mechanical energy.
Common examples are car engines and steam engines, where heat from fuel is converted into motion.
True or False:
Heat engines can work by using only electrical energy.
False
Heat engines rely on thermal energy to perform mechanical work, not just electrical energy.
What is the conversion equation from Fahrenheit to Celsius?
C = (F - 32) * 5/9
This formula allows you to convert Fahrenheit temperature readings to Celsius. For example, 32°F equals 0°C.
How is temperature commonly measured?
Using a thermometer.
Thermometers can use different methods (e.g., liquid expansion, infrared, or digital sensors) to measure temperature.
True or False:
The boiling point of water decreases as altitude increases.
True
At higher altitudes, atmospheric pressure is lower, so water boils at lower temperatures.
How do impurities affect the boiling point of water?
They raise the boiling point.
Adding salt to water increases the boiling point and decreases the freezing point, which is called boiling point elevation.
True or False:
The phases of water are solid (ice), liquid (water), and gas (water vapor or steam), but not plasma.
False
In addition to solid, liquid, and gas, water can also exist as plasma under extreme conditions, such as very high temperatures.
What is an endothermic reaction?
A reaction that absorbs heat.
Endothermic reactions, such as photosynthesis, require energy input to proceed and lower the surrounding temperature.
What is an exothermic reaction?
A reaction that releases heat.
Exothermic reactions, such as combustion, release heat energy to the surroundings, increasing their temperature.
Fill in the blank:
When a cold pack is activated, it absorbs heat from its surroundings. This is an example of a ______ reaction.
endothermic
Endothermic reactions, like the one in cold packs, absorb energy from the surroundings, causing a cooling effect.
Fill in the blank:
When wood burns in a fireplace, it releases heat and light. This is an example of a ______ reaction.
exothermic
Exothermic reactions release energy, usually in the form of heat, light, or sound, warming their surroundings.
What does the prefix endo- mean in thermodynamics?
Inside
Endo comes from Greek, indicating that energy is absorbed into the system, as in endothermic reactions.
What does the prefix exo- mean in thermodynamics?
Outside
Exo comes from Greek, indicating that energy is released to the surroundings, as in exothermic reactions.
True or False:
In an exothermic reaction, bond formation releases more energy than bond breaking.
True
In exothermic reactions, more energy is released when new bonds form than is required to break the original bonds.
Define:
Enthalpy
A thermodynamic property that measures the heat content of a system.
Enthalpy is critical in understanding energy changes during chemical and physical processes and is typically measured in joules (J) or kilo-joules (kJ).
Define:
Entropy
The measure of disorder or randomness in a system.
Entropy reflects the tendency of systems to move towards greater disorder. As entropy increases, the system becomes less organized, and usable energy decreases.
Melting of ice is an example of which type of reaction?
Endothermic
The melting of ice absorbs heat, making it an endothermic reaction that requires energy to break the bonds between ice molecules.
What happens to energy during freezing?
Energy is released as heat.
Freezing occurs when a liquid loses energy and solidifies.
Photosynthesis is an example of which type of reaction?
Endothermic
In photosynthesis, plants absorb sunlight to convert carbon dioxide and water into glucose, which requires heat energy.
Nuclear fission is an example of which type of reaction?
Exothermic
Nuclear fission releases a large amount of energy when unstable atomic nuclei split, making it an exothermic reaction.
Fill in the blank:
The enthalpy of reaction for endothermic reactions is _______.
ΔH > 0
(positive change in enthalpy)
A positive enthalpy change (ΔH > 0) means the reaction absorbs heat from its surroundings.
Fill in the blank:
The enthalpy of reaction for exothermic reactions is ________.
ΔH < 0
(negative change in enthalpy)
A negative enthalpy change (ΔH < 0) indicates that energy is released during the reaction.
What defines a closed system in thermodynamics?
A system that allows energy exchange but no matter exchange with its surroundings.
In a closed system, energy can flow in and out, but mass remains constant within the system.
Fill in the blank:
The first law of thermodynamics is also known as the _________.
Law of Conservation of Energy
This law states that energy cannot be created or destroyed; it can only change forms.
True or False:
The total energy in the universe can change over time.
False
The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed. This means the total energy in an isolated system (like the universe) remains constant.
What are the most common units for measuring heat?
- Joules (J)
- Calories
- British Thermal Units (BTU).
Heat is the transfer of thermal energy, and these units quantify that energy. Temperature, however, is measured in Celsius, Kelvin, or Fahrenheit.
What is calorimetry?
The process of measuring heat transfer during physical or chemical changes.
Calorimeters are instruments used to measure heat changes in reactions. This helps determine properties such as specific heat capacity or enthalpy changes.
What does the unit J/g°C represent?
Joules per gram per degree Celsius.
This unit measures specific heat capacity, which tells you how much heat energy (in joules) is needed to raise the temperature of 1 gram of a substance by 1°C.
Fill in the blank:
A BTU is the amount of energy required to raise the temperature of 1 pound of water by ______ degree Fahrenheit.
1
A BTU is used to measure energy in heating systems and is approximately equal to 1,055 joules.
What is the purpose of a bomb calorimeter?
To measure the heat released in combustion reactions.
Bomb calorimeters are used to determine the energy content of fuels and foods by measuring the heat produced when substances are burned under controlled conditions.
What does Kinetic Molecular Theory (KMT) describe?
The behavior of particles, especially in gases.
KMT helps explain properties like pressure, temperature, and volume by modeling the motion and collisions of molecules.
What are the five main assumptions of Kinetic Molecular Theory?
- Gases are composed of particles in random, constant motion.
- Gases move in a straight line until they collide.
- Gas molecules are not attracted to one another or the container.
- Collisions between gas molecules are perfectly elastic.
- Average kinetic energy depends only on the temperature of the gas.
Some sources may vary in the number of assumptions.
True or False:
Kinetic Molecular Theory assumes that gas molecules are attracted to each other.
False
Kinetic Molecular Theory assumes that gas molecules have no intermolecular attractions and move independently.
Fill in the blank:
Boyle’s Law describes the _______ relationship between pressure and volume at constant temperature.
inverse
Boyle’s Law states that as the volume of a gas increases, its pressure decreases, and vice versa, provided the temperature is held constant. This is mathematically expressed as P1V1 = P2V2.
Fill in the blank:
Charles’ Law describes the _______ relationship between the temperature and volume of a gas when other factors are held constant.
direct
Charles’ Law can be expressed as T1/V1 = T2/V2, showing how volume increases with temperature at constant pressure.
Fill in the blank:
According to Avogadro’s Law, if the number of moles of gas increases, the volume of the gas will ________, assuming temperature and pressure are constant.
increase
Avogadro’s Law shows that volume and moles are directly proportional, meaning if the number of moles increases, the volume increases in direct proportion, as long as temperature and pressure stay the same.
How is kinetic energy (KE) calculated for an ideal gas?
KE = (3/2) RT
where:
R is the gas constant
T is the temperature in Kelvin
Kinetic energy depends on temperature and the gas constant.
True or False:
Tire pressure increases when the temperature decreases.
False
Cooler temperatures slow molecules, reducing tire pressure.
Define:
Phase diagram
A graph showing the temperature and pressure conditions for solid, liquid, and gas phases.
Phase diagrams illustrate equilibrium and help predict phase behavior.
What are supercritical fluids?
Fluids above the critical point, exhibiting both liquid and gas properties.
Supercritical fluids can diffuse through solids like gases but dissolve substances like liquids.
True or False:
The critical point is where liquid and gas phases merge, and phase transitions like condensation no longer occur.
True
Beyond the critical point, the distinction between liquid and gas disappears, and gases cannot be liquefied, regardless of pressure.
What is the difference between triple point and critical point?
Triple point is where all phases coexist; the critical point is where gas can’t be turned into liquid.
The critical point marks the end of the liquid-gas boundary, while the triple point is where solid, liquid, and gas exist together.
What does a heating curve demonstrate?
Temperature vs. time
A heating curve shows how temperature changes with added heat, including phase transitions.
Fill in the blank:
The average kinetic energy of gas molecules is directly proportional to the ________.
temperature (in Kelvin)
Higher temperature increases the kinetic energy of gas molecules, as the molecules move faster with increased heat.
True or False:
Gases can be compressed because there is a significant amount of space between their molecules.
True
Gases have large spaces between molecules, allowing compression.
What is the ideal gas law equation?
PV = nRT
where:
P is pressure
V is volume
n is moles
R is the ideal gas constant
It describes the relationship between pressure, volume, temperature, and moles of gas.
What is the mathematical expression for Avogadro’s Law?
V₁/n₁ = V₂/n₂
This equation represents the relationship between the initial and final volumes (V₁, V₂) and the number of moles (n₁, n₂) of a gas, at constant temperature and pressure.
What is the value of the ideal gas constant R when using atmospheric pressure?
0.0821 L ⋅ atm / mol ⋅ K
R is constant in all gas law equations involving pressure, volume, and temperature.
What is the conversion formula from Celsius to Kelvin?
K = °C + 273.15
This conversion is crucial for gas law calculations, as temperature must be expressed in Kelvin, not Celsius, to ensure accurate results.
Calculate the volume of gas using the ideal gas law.
Given 0.988 mol, 1.47 atm, and 425 K.
V = 23.4 L
R = 0.0821 L ⋅ atm / mol ⋅ K
Use the ideal gas law formula PV=nRT. Rearrange to solve for volume V = nRT/P. Substitute the given values to calculate volume.
Calculate the number of moles of gas using the ideal gas law.
Given 1.789 atm, 4.78 L, and 306.15 K.
n = 0.34 mol
R = 0.0821 L ⋅ atm / mol ⋅ K
Use the ideal gas law formula PV=nRT. Rearrange to solve for moles n = PV/RT. Plug in the values for pressure, volume, temperature, and the ideal gas constant to find the number of moles.
Fill in the blank:
The ideal gas constant is expressed as _____.
R
R is a key constant in the ideal gas law, ensuring consistent units across calculations.
What does the ideal gas law combine?
Boyle’s, Charles’s, and Avogadro’s laws
These laws describe the relationship between pressure, volume, temperature, and moles.
What does STP stand for in gas law?
Standard Temperature and Pressure
STP refers to a standard set of conditions used in gas law calculations: a temperature of 0°C (273.15 K) and a pressure of 1 atm and provide a reference point for comparing the properties of gases and ensure consistency across different experiments and calculations.
True or False:
An ideal gas is a gas that follows the ideal gas law.
True
Ideal gases follow the combined principles of Boyle’s, Charles’s, and Avogadro’s laws.
What unit is pressure measured in according to the ideal gas law?
Atmosphere (atm)
When using the gas constant R=0.0821L⋅atm/mol⋅K, pressure must be expressed in atm. Other units like pascals (Pa) or mmHg can be used with different values of R.
True or False:
Water vapor in the air behaves exactly like an ideal gas.
False
Water vapor is a real gas and does not always follow the ideal gas law, especially at high pressures or low temperatures, where intermolecular forces cause deviations from ideal behavior.
How is the volume of a gas measured?
in liters (L)
In gas law calculations, volume is typically measured in liters to maintain consistency with the ideal gas law equation (PV = nRT), ensuring that all units align properly.
True or False:
In a closed container, if the temperature of the gas is doubled, its volume will also double.
False
According to the Ideal Gas Law, while temperature and volume are related (Charles’ Law), the volume does not double if the temperature is doubled unless the pressure is held constant.
Fill in the blank:
Gay-Lussac’s Law states that the pressure of a gas is _______ proportional to its temperature when the volume is held constant.
directly
This means that if the temperature of a gas increases, its pressure will also increase, provided the volume doesn’t change. The law can be mathematically represented as P1/T1 = P2/T2, where P is pressure and T is temperature in Kelvin.
What happens to the pressure inside a basketball when you dribble it on a hot day?
It increases.
As the temperature of the air inside the basketball rises (due to contact with the hot surface), the pressure increases according to Gay-Lussac’s Law, which relates pressure and temperature at constant volume.
True or False:
When you inflate a balloon, the gas inside does not obey the ideal gas law because it is not in a rigid container.
False
Even though a balloon is flexible, the gas inside still follows the ideal gas law, assuming conditions of temperature, pressure, and volume are controlled, and the gas behaves ideally within the balloon’s limits.
