Heat and Temperature

By: JVDCJ

Objectives Explain the difference between heat and temperature. State the relationship between movement of

molecules and temperature. Determine the factors that affect heat and

temperature. Determine the units of heat and temperature. Identify the types of temperature scale. Derive the formula for Celsius and Fahrenheit. Convert one temperature unit to the other.

What did you observed on the picture?

What did you observed?

Activity

HEAT VESUS TEMPERATURE

What will happen when you touch a hot stove?

What will happen when you touch an ice?

What is Heat??

Heat is energy in transit as a result of temperature difference.

Heat = Thermal Energy!! Thermal Energy = the total energy of all

of the particles in a material or object. Throughout the ages people have invented a variety of

devices to help create and capture heat for use.

What will happen to the thermal energy of a substance when it gives off heat? Thermal Energy decreases.

What will happen to the thermal energy of a substance when it absorbs heat? Thermal Energy increases.

For two things in thermal contact.

Is the statement, “heat flow is from the higher temperature substance to lower temperature substance” the same as “a flow from a substance with more thermal energy to a substance with less thermal energy? Explain your answer.

Not necessarily.

A bowl of warm water has more thermal energy than a red hot thumbtack.

This is so because thermal energy depends on the number of molecules in a substance. The more molecules in a substance the more thermal energy it has.

Its temperature will rise by only 10C, because there are twice as many molecules in 2L of water and each molecule receives only half as much energy on the average.

Measuring Heat

Since heat is a form of energy, it is measured in joules.

Heat is also measured in calorie. Calorie is the amount of heat required to

change the temperature of 1 gram of water by 1Celius degree.

Measuring Heat

1 calorie (cal)= 4.186 joules (J) 1 kilocalorie(kcal) = 1000 calorie (cal) 1 kilocalorie (kcal) = 4.186 x 103 joules (J)

Temperature is the quantity that indicates how warm or hot or cold an object is with respect to some standard.

What is temperature?

TRUE OR FALSE?

Temperature is a measure of the total kinetic energy in a substance.

FALSE

Temperature is a measure of the average translational kinetic energy of molecules in a substance.

Measuring Temperature

Thermometer: Mechanical or electrical device for measuring temperature. Early thermometer was invented by Galileo.

Scale: A series of equally measured sections that are marked and numbered for use in measurement.

Thermometer

The device used to measure temperature of a substance.

Celsius, Fahrenheit, Kelvin are the common T scale used.

Thermometry is the science of measuring the temperature of matter.

Celsius Scale

Celsius Scale: Most commonly used in Canada. Unit of temperature is called a degree. Based on the boiling and freezing points of water.

Boiling Point: The temperature at which water boils. 100o C at sea level.

Freezing Point: The temperature at which water freezes. 0o C at sea level.

Another Scale…

Kelvin is another way of measuring temperature.

Scientists use Kelvin to explain the behaviour of gases.

“Absolute Zero” is measured in Kelvin – which is the coldest possible temperature

0 Kelvin = -273 ºC

Right Device for the Job

Each thermometer has a sensor – a material which is affected by changes in the environment (such as temperature)

The sensor produces a signal (information about temperature, such as an electrical current) which affects a responder (a pointer, light or other mechanism that uses the signal in some way)

Why is it important to ensure considerable time for the thermometer to be in contact with the substance being measured? Because, what the thermometer really

displays is its own temperature. When a thermometer is in thermal contact

with something whose temperature we wish to know, energy flow between the two until their temperatures are equal and thermal equilibrium is established.

Comparison of the T Scale

Temperature Celsius Fahrenheit Kelvin

Inventor Anders Celsius Gabriel Daniel Fahrenheit

William Thompson (Lord Kelvin)

Unit 0C 0F K

Freezing Point 00C 320F 273 K

Boiling Point 1000C 2120F 373 K

Body Temperature 370C 98.6 310.15

Room Temperature 200C 68 293

Absolute Zero -2730C -459 0

Temperature Scale Conversion

C = (5/9) (F – 32) F = (9/5) C +32 K = C + 273.15 C = K – 273.15

Sparkles produced by the firework and welding are of very high temperature.

Scald is burn injury caused by hot liquid or gas.(e.g. boiling water)

Sparkle of fireworks and welding have higher temperature as compared to boiling

Based on the pictures presented, why is it people who come into contact with the sparkles are not injured but people who come into contact with boiling water are injured?

Evaluation1. Why does a penny becomes warmer when it is struck by a hammer?

2. Suppose you apply the a flame to 1L of water for a certain time and its temperature rises by 20C. If you apply the same flame for the same time to 2L of water, by how much will its temperature rise?How is the motion of the particles within a substance related to thermal energy of the substance?

3. The temperature of a certain substance is 400C. What is the F and K equivalent of this?

4. What is the F equivalent of the melting points of:

a. Mercury (234K)

b. Copper (1356K)

c. Oxygen (54.4K)

Assignment 1. What is thermal expansion? 2. Formula for the type of thermal

expansion. 3. State the following law that involves

expansion of gases and express them in mathematical form:

A. Boyle’s Law B. Charles’s Law C. Gay Lussac’s Law D. Comnined Gas laws

Topic 8: Conserving Our Fossil Fuel Resources

Insulate homes and water lines Reduce the amount of energy we use Install a programmable thermostat Carpool

Others????