Heat Unit chapters 9 and 10

Heat Unit chapters 9 and 10

First Chapter 9Pages 134-150

First Chapter 9Pages 134-150

Thermal EnergyThermal Energy

What is matter?Matter is anything that has mass.

Mass is composed of atoms. These atoms are constantly moving.

The state of matter decides how fast these atoms move.

The movement of these atoms produces energy.

What is matter?Matter is anything that has mass.

Mass is composed of atoms. These atoms are constantly moving.

The state of matter decides how fast these atoms move.

The movement of these atoms produces energy.

Thermal Energy Definition

Thermal Energy Definition

Thermal energy in a substance is the total energy of all its atoms and molecules.

What does this really look like? Let’s find out!

Thermal energy in a substance is the total energy of all its atoms and molecules.

What does this really look like? Let’s find out!

In Terms of Thermal Energy

In Terms of Thermal Energy

Hot vapors are composed of molecules traveling very fast. HIGH THERMAL ENERGY

Liquids are composed of molecules that travel fast. MEDIUM THERMAL ENERGY

Solids are composed of molecules that travel slowly. LOW THERMAL ENERGY

Hot vapors are composed of molecules traveling very fast. HIGH THERMAL ENERGY

Liquids are composed of molecules that travel fast. MEDIUM THERMAL ENERGY

Solids are composed of molecules that travel slowly. LOW THERMAL ENERGY

TemperatureTemperature

Definition: the degree of hotness or coldness of a body or environment (corresponding to its molecular activity)

Molecular activity can be defined as movement (expansion or contraction)

Definition: the degree of hotness or coldness of a body or environment (corresponding to its molecular activity)

Molecular activity can be defined as movement (expansion or contraction)

TemperatureTemperature

A molecule is something that is composed of two or more atoms.

Temperature is related to the random motion of molecules.

Temperature is proportional to the average kinetic energy of the molecules.

A molecule is something that is composed of two or more atoms.

Temperature is related to the random motion of molecules.

Temperature is proportional to the average kinetic energy of the molecules.

TemperatureTemperature

Celsius Hundred step scale

0º C freezing point

100ºC boiling point

Named after Anders Celsius (1701-1744)

Used in all countries that use metric system

Celsius Hundred step scale

0º C freezing point

100ºC boiling point

Named after Anders Celsius (1701-1744)

Used in all countries that use metric system

Fahrenheit Used in the USA

32ºF freezing point

212ºF boiling point

Named after Gabriel Fahrenheit (1686-1736)

Fahrenheit Used in the USA

32ºF freezing point

212ºF boiling point

Named after Gabriel Fahrenheit (1686-1736)

QuestionQuestion

What is the difference between thermal energy and temperature?

What is the difference between thermal energy and temperature?

Kelvin ScaleKelvin Scale

The absolute scaleKelvin cannot be negative.

0 K=-273ºCConversion:

K=C+273At 0 K, no molecular movement is possibleAbsolute Zero

The absolute scaleKelvin cannot be negative.

0 K=-273ºCConversion:

K=C+273At 0 K, no molecular movement is possibleAbsolute Zero

KelvinKelvin

Named after British physicist, Lord Kelvin

Absolute zero is a limit.

A limit is something that cannot be reached.

Today’s technology can get close to absolute zero, but not reach it.

Named after British physicist, Lord Kelvin

Absolute zero is a limit.

A limit is something that cannot be reached.

Today’s technology can get close to absolute zero, but not reach it.

Homework (due THURSDAY!)

Homework (due THURSDAY!)

Complete RQ 1-7 pg 148If you want a head start, do them all!

Complete RQ 1-7 pg 148If you want a head start, do them all!

HeatHeat

Direction of heat flow is ALWAYS from hot to cold. Heat is the movement of thermal energy due to a temperature difference between objects.

Rubbing hands produces heat. Does the object have heat in it? Why or why not?

Direction of heat flow is ALWAYS from hot to cold. Heat is the movement of thermal energy due to a temperature difference between objects.

Rubbing hands produces heat. Does the object have heat in it? Why or why not?

Heat and Thermal Energy

Heat and Thermal Energy

Example: Drop a red hot piece of metal into a large bucket of warm water. Thermal energy does not flow from the water to the metal, but from the HOT metal to the COLD water.

Heat will flow until objects reach equilibrium.

Example: Drop a red hot piece of metal into a large bucket of warm water. Thermal energy does not flow from the water to the metal, but from the HOT metal to the COLD water.

Heat will flow until objects reach equilibrium.

ColdCold

Cold is the absence of thermal energy like black is the absence of light. Remember that heat travels from hot to cold.

Therefore cold does not travel at all because its not “a thing” itself.

Cold is the absence of thermal energy like black is the absence of light. Remember that heat travels from hot to cold.

Therefore cold does not travel at all because its not “a thing” itself.

QuestionQuestion

Suppose you apply a flame to 1 L of water and its temperature rises by 3°C. If you apply the same flame for the same length of time to 3 L of water, by how much does its temperature rise?

Why?

Suppose you apply a flame to 1 L of water and its temperature rises by 3°C. If you apply the same flame for the same length of time to 3 L of water, by how much does its temperature rise?

Why?

Units of EnergyUnits of Energy

Energy is measured in joules

4.18 J of heat=1 calorieA calorie is the energy required to change the temperature 1°C of 1 gram of water.

A Calorie is 1000 calories

Energy is measured in joules

4.18 J of heat=1 calorieA calorie is the energy required to change the temperature 1°C of 1 gram of water.

A Calorie is 1000 calories

HomeworkHomework

RQ 1-12 pg 148-149RQ 1-12 pg 148-149

Rules to EnergyRules to Energy

With everything in life, there are always rules to follow.

These rules, or laws, are called the Laws of Thermodynamics.

This is just a way to say why and how thermal energy behaves.

With everything in life, there are always rules to follow.

These rules, or laws, are called the Laws of Thermodynamics.

This is just a way to say why and how thermal energy behaves.

The 1st Law of ThermodynamicsThe 1st Law of Thermodynamics

Whenever heat flows into or out of a system, the gain or loss of thermal energy equals the amount of heat transferred.

What is a system? This law really means that you are not powerful enough to create energy, you just reuse it.

Whenever heat flows into or out of a system, the gain or loss of thermal energy equals the amount of heat transferred.

What is a system? This law really means that you are not powerful enough to create energy, you just reuse it.

The 2nd Law of ThermodynamicsThe 2nd Law of Thermodynamics

Heat never spontaneously flows from a cold substance to a hot substance.

Two examples:Keep the doors shut in the winter and the summer.

Listen to your parents (They know science after all!)

Heat never spontaneously flows from a cold substance to a hot substance.

Two examples:Keep the doors shut in the winter and the summer.

Listen to your parents (They know science after all!)

The Third Law of Thermodynamics

The Third Law of Thermodynamics

No system can reach absolute zero. Why? Because it’s the lower limit of temperature.

Scientists have came close, 1 millionth of a Kelvin close.

No system can reach absolute zero. Why? Because it’s the lower limit of temperature.

Scientists have came close, 1 millionth of a Kelvin close.

Specific Heat Capacity

Specific Heat Capacity

Different substances have the capacity to hold thermal energy for a longer time. Soup Toast

Example: it takes longer for a pot of water to boil than it takes an iron to heat up.

Different materials require more thermal energy to heat them up.

Different substances have the capacity to hold thermal energy for a longer time. Soup Toast

Example: it takes longer for a pot of water to boil than it takes an iron to heat up.

Different materials require more thermal energy to heat them up.

In other words…In other words…

….depending on the substance, it takes more energy to get the molecules to move.

Water is a liquid, molecules move more freely, while in a solid, the molecules are stuck together.

….depending on the substance, it takes more energy to get the molecules to move.

Water is a liquid, molecules move more freely, while in a solid, the molecules are stuck together.

Definition of Specific HeatDefinition of Specific Heat

The specific heat capacity of any substance is defined as the quantity of heat required to change the temperature of a unit mass of the substance by 1 degree.

Specific heat is related to the resistance to change temperature.

Water has a very high specific heat capacity. It takes a long time to heat up, and a lot of time to cool down.

The specific heat capacity of any substance is defined as the quantity of heat required to change the temperature of a unit mass of the substance by 1 degree.

Specific heat is related to the resistance to change temperature.

Water has a very high specific heat capacity. It takes a long time to heat up, and a lot of time to cool down.

HomeworkHomework

RQ 13-16 pg 148 & 149RQ 13-16 pg 148 & 149

Organize your Thoughts!

Organize your Thoughts!

Many terms in this chapter relate to each other. Create a graphic organizer (including definitions or pictures and real-life examples of each) with the following terms:

Temperature3 Laws of ThermodynamicsThermal EnergyHeatColdSpecific HeatThermal Expansion

Many terms in this chapter relate to each other. Create a graphic organizer (including definitions or pictures and real-life examples of each) with the following terms:

Temperature3 Laws of ThermodynamicsThermal EnergyHeatColdSpecific HeatThermal Expansion