16.1: Thermal Energy and Matter - Polk School District Thermal Energy and Matter . Heat •Heat is the transfer of thermal energy from one object to another because of a temperature

16.1: Thermal Energy and Matter

Heat • Heat is the transfer of thermal

energy from one object to another because of a temperature difference.

• Heat flows spontaneously from hot objects to cold objects.

Temperature

• Temperature is a measure of how hot or cold an object is compared to a reference point.

•On the Kelvin scale, absolute zero is defined as a temperature of 0 kelvins.

Temperature • As an object heats up, its particles move

faster, on average. The average kinetic energy of the particles increases.

• One way that heat flows is by the transfer of energy in collisions.

• On average, high-energy particles lose energy. Low-energy particles gain energy.

Thermal Energy • Thermal energy is the total

potential and kinetic energy of all the particles in an object.

• Thermal energy depends on the mass, temperature, and phase (solid, liquid, or gas) of an object.

Specific Heat • The amount of heat needed to raise

the temperature of one gram of a material by one degree Celsius.

• The lower a material’s specific heat, the more its temperature rises when a given amount of energy is absorbed by a given mass.

Calculating Specific Heat

• In this formula, heat is in joules, mass is in grams, specific heat is in J/g•°C, and the temperature change is in degrees Celsius.


An iron skillet has a mass of 500.0 grams. The specific heat of iron is

0.449 J/g•°C. How much heat must be absorbed to raise the skillet’s

temperature by 95.0°C?


• An iron skillet has a mass of 500.0 grams. The specific heat of iron is 0.449 J/g•°C. How much heat must be absorbed to raise the skillet’s temperature by 95.0°C?


How much heat is needed

to raise the temperature of 100.0 g of water by

85.0°C?


How much heat is needed to raise the temperature of 100.0 g of water by 85.0°C?

Q = m * c * ∆T = (100.0 g)(4.18 J/g•°C)(85.0°C)

= 35.5 kJ


How much heat is

absorbed by a 750-g iron skillet when its

temperature rises from 25°C to 125°C?


How much heat is absorbed by a 750-g iron skillet when its temperature

rises from 25°C to 125°C?

Q = m * c * ∆T = (750 g)(0.449 J/g•°C)(125°C – 25°C)

= (750 g)(0.449 J/g•°C)(100°C) = 34 kJ


• In setting up an aquarium, the heater transfers 1200 kJ of heat to 75,000 g of water. What is the increase in the

water’s temperature? (Hint: Rearrange the specific heat formula

to solve for ∆T


• In setting up an aquarium, the heater transfers 1200 kJ of heat to 75,000 g of water. What is the increase in the water’s temperature? (Hint: Rearrange the specific heat formula to solve for ∆T

∆T = Q / (m x c) = 1,200,000 J/(75,000 g × 4.18 J/g•°C)

= 3.8°C


• To release a diamond from its setting, a jeweler heats a 10.0-g

silver ring by adding 23.5 J of heat. How much does the temperature of the silver

increase?


• To release a diamond from its setting, a jeweler heats a 10.0-g silver ring by adding 23.5 J of heat. How much does the temperature of the silver increase?

∆T = Q / (m x c) = 23.5 J/(10.0 g × 0.235 J/g•°C)

= 10.0°C


• What mass of water will

change its temperature by 3.0°C when 525 J of

heat is added to it?


• What mass of water will change

its temperature by 3.0°C when 525 J of heat is added to it?

m = Q / (∆T x c) = 525 J/(3.0°C × 4.18 J/g•°C)

= 42 g


How many joules of heat are

needed to raise the temperature of 10g of aluminum from 22 C to

55 C, if the specific heat of aluminum is 0.90J/g C?


100g of 4 C water is heated until its temperature is 37 C. Calculate the amount of heat energy needed to cause this

rise in temperature.


How much heat is needed to raise the temperature of 16g of iron from 25 C to

175 C?

Calorimeter

An instrument used to measure changes in

thermal energy.

16.1: Thermal Energy and Matter - Polk School District Thermal Energy and Matter . Heat •Heat is the transfer of thermal energy from one object to another because of a temperature

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