Thermal Energy and Heat Chapter 16 Thermal Energy and Heat Thermal energy is used to help this locomotive steam along

16.1 Key Concepts In what direction does heat flow spontaneously? What causes thermal expansion? How is a change in temperature related to specific heat? On what principle does a calorimeter operate?

In the 1700s, most scientists thought that heat was a fluid called calorie that flowed between objects Count Rumford noticed that when drilling brass canons, heat ______________ when drilling stopped Rumford concluded that heat could _______ be a kind of matter, but was related to the _______________ of the drill subsided not motion

Heat flows spontaneously from ______ objects to _________ objects. Work and Heat Heat is the _________________ of thermal energy from one object to another because of a temperature ___________________. transfer difference Heat flows spontaneously from ______ objects to _________ objects. Think of holding an ice cube in your hand… describe the flow of heat. warm cool Hand  ice cube (melts)

Temperature Temperature is related to the average _____________ energy of the particles in an object due to their random ______________ through space. Temperature is a measure of how _______ or ________ an object is compared to a reference point. On the Celsius scale, the reference points are the freezing and boiling points of ______________. On the Kelvin scale, absolute zero is defined as a temperature of ______ ___________________. kinetic motion hot cold water Kelvin

As an object heats up, its particles move _____________, on average. Temperature As an object heats up, its particles move _____________, on average. Overall, _________________ transfer thermal energy from hot to cold objects. Thermal energy is the total _____________ and ______________ energy of all the particles in an object. faster collisions kinetic potential

Thermal energy depends on the… ______________ ________________ and _______________ (solid, liquid, or gas) of an object mass temperature phase

Thermal energy depends on mass. A cup of tea and a teapot full of tea can have the ____________ temperature. The average kinetic energy of the particles is the _________ in the cup and the pot. There is __________ thermal energy in the teapot because it contains more _______________. same same more particles

Thermal energy depends on temperature. Compare a cup of hot tea with a cup of cold tea. In both cups, the tea has the same __________ and _______________ of particles. The average kinetic energy of particles is higher in the _________ tea, so it has greater thermal energy. mass number hot

The tea is at a ____________ temperature than the lemonade. Thermal Energy Thermal energy depends on mass and temperature. The tea is at a ____________ temperature than the lemonade. The lemonade has more _______________ energy because it has many more ___________ higher thermal particles

Thermal Contraction and Expansion Thermal expansion is an increase in the _______________ of a material due to a temperature increase. volume Thermal expansion occurs when particles of matter move _________________ apart as temperature increases. farther

If you bring the balloon inside, it ___________ Thermal Energy If you take a balloon outside on a cold winter day, it _______________ in a process of thermal ________________. Slower particles collide ________ often and exert less force. shrinks contraction less If you bring the balloon inside, it ___________ _____________ expand more than liquids and liquids usually expand more than solids. expands Gases

Thermal Energy As temperature increases, the alcohol in a thermometer expands, and its ____________ increases in proportion to the increase in temperature. In an oven thermometer, strips of steel and brass expand at different rates as the coil heats up. The coil ____________, moving the needle on the temperature scale. height unwinds

Specific Heat Specific heat is the ______________ of heat needed to raise the temperature of _______ of a material by ________. amount 1 g 1 °C The lower a material’s specific heat, the _________ its temperature __________ when a given amount of energy is absorbed by a given mass. changes more

Specific Heat Think about going to the beach on a warm summer day…what heats up faster: the air around you or the water? the sand or the water?

Specific Heat

Q is _________ in joules, m is __________ in grams, Specific Heat In this formula… Q is _________ in joules, m is __________ in grams, c is __________________ in J/g•°C ΔT is the _______________________ in degrees Celsius. heat mass Specific heat change in temperature

Calculating Specific Heat 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? Q = (500.0 g) (0.449 J/g·°C) (95.0 °C) Q = 21,300 J

A calorimeter is used to measure specific heat. A ______________________ is an instrument used to measure changes in thermal energy. A calorimeter is used to measure specific heat. calorimeter

A sample is heated and placed __________ the calorimeter. Specific Heat A sample is heated and placed __________ the calorimeter. The temperature change of the ______________ is observed. The hot sample will _____________ energy but the water will ____________ it inside water release absorb

What is the difference between temperature and heat? Assessment Questions What is the difference between temperature and heat? Measure of how hot or cold an object is Transfer of thermal energy (Kinetic energy)

What causes a gas to expand when its temperature is increased? Assessment Questions What causes a gas to expand when its temperature is increased? The number of particles increases as temperature increases. Each particle expands as its temperature increases, so the total volume increases. As temperature increases, more electrons leave atoms and move separately. As gas particles move faster, they overcome some forces of attraction.

Water has a high specific heat…what does that mean? Assessment Questions Water has a high specific heat…what does that mean? Water requires a large energy transfer to change is temperature

How does a calorimeter work? Assessment Questions How does a calorimeter work? A hot sample transfers energy to the water… The temperature change of the water can be recorded