Things to ponderThings to ponder

Why does it take Lake Sammamish so Why does it take Lake Sammamish so long to warm up?long to warm up?

How do fireworks work?How do fireworks work?

What are you feeling when you feel What are you feeling when you feel warm?warm?

What is energy? What is heat? What is What is energy? What is heat? What is the difference between them?the difference between them?

What is heat?What is heat?What is temperature?What is temperature?What is the difference What is the difference

between heat and between heat and temperature?temperature?

What does temperature What does temperature measure?measure?

The The raterate of movement of atoms and of movement of atoms and moleculesmolecules

If temperature is a measure of the If temperature is a measure of the speed of molecules,speed of molecules,

Then, what is Then, what is HEAT?HEAT?

Which has more heat?Which has more heat?

one drop of water at 100⁰ Cone drop of water at 100⁰ C

or one cup of water at 100⁰ Cor one cup of water at 100⁰ C

While temperature is a measure of While temperature is a measure of the speed of molecules,the speed of molecules,

Heat is a measure of the Heat is a measure of the quantityquantity of of energy present. Heat is a form of energy present. Heat is a form of Energy.Energy.

What do you think will happen to the temperature of water What do you think will happen to the temperature of water when I add the same mass of boiling water to it?when I add the same mass of boiling water to it?

Why?Why?

What will happen to the temperature of water when the What will happen to the temperature of water when the same mass of metal is added to it?same mass of metal is added to it?

Why is the temperature change different with a metal than Why is the temperature change different with a metal than water?water?

Q(water)=s(water)m(water)∆tQ(water)=s(water)m(water)∆tQ= Energy requiredQ= Energy requiredM=Mass of objectM=Mass of object∆∆t= Change in temperaturet= Change in temperatureWhat do you think s is???What do you think s is???

How can scientists measure the How can scientists measure the amount of heat that is contained in amount of heat that is contained in something?something?

You measure by transfer of energy You measure by transfer of energy from a hot object to a cooler object.from a hot object to a cooler object.

A calorimeter is an instrument that A calorimeter is an instrument that measures heat by the transfer of measures heat by the transfer of energy.energy.

One unit of energy is the calorie:One unit of energy is the calorie:

What is the definition of a calorie?What is the definition of a calorie?

The amount of energy needed to The amount of energy needed to raise the raise the temperature of 1.0 gram temperature of 1.0 gram of water 1.0 of water 1.0 degree Celcius.degree Celcius.

Chemists don’t use calories. Instead, Chemists don’t use calories. Instead, we use the unit we use the unit joulejoule. One calorie . One calorie equals 4.184 joulesequals 4.184 joules

Specific HeatSpecific Heat

The specific heat measures how The specific heat measures how much energy one gram of a much energy one gram of a substance absorbs before its substance absorbs before its temperature increases one degree temperature increases one degree Celcius.Celcius.

Every pure substance has its own Every pure substance has its own unique specific heatunique specific heat

In summary, to measure energy In summary, to measure energy transferred, transferred, QQ, we must record the , we must record the following things in the absorbing following things in the absorbing medium:medium:– Change in temperature in degrees Celcius: Change in temperature in degrees Celcius:

∆T∆T– Mass of the medium: Mass of the medium: mm– Specific heat of the medium in Joules/ gram: Specific heat of the medium in Joules/ gram:

SS

Q = SmQ = Sm∆T∆T

Can we determine the amount of Can we determine the amount of energy transferred in the water?energy transferred in the water?We need specific heat We need specific heat S= S= Q m* ∆t m* ∆tS= The amount of energy it requires to raise 1 S= The amount of energy it requires to raise 1 g of water 1 degree Cg of water 1 degree CThe specific heat of water is The specific heat of water is 4.184 J4.184 J

g*Cg*C

How much energy was added to the to the How much energy was added to the to the water?water?

How could we determine the specific How could we determine the specific heat of a washer (an unknown heat of a washer (an unknown metal)?metal)?

Keep in mind the amount of energy is Keep in mind the amount of energy is never lost just transferred.never lost just transferred.

What do you think?What do you think?

Could you determine the amounts Could you determine the amounts of another metal?of another metal?

How?How?