Heat Temperature and Specific Heat What is temperature

Heat, Temperature, and Specific Heat

What is temperature? • Measure of average KE of molecules • Units of Temp => o. C

Specific Heat • Specific Heat is the amount of heat needed to raise the temperature of 1 g of substance 1 o. C • We represent it as Cp • Units are J/go. C OR cal/go. C

Specific Heat • Specific heat is specific for different materials, much like properties such as boiling points and freezing points • Different substances have different specific heats

HEAT • Heat is represented as Q • Units in Joules (J) • 1 cal = 4. 184 J • Heat is defined as Q = m*Cp*ΔT

What the terms mean Q = m*Cp*ΔT • • Q = heat (J) m = mass (g) Cp = specific heat (J/go. C) ΔT = change in temp (o. C) ΔT is final temp minus initial temp

Q = m*Cp*ΔT How would Q change if the mass of a substance increased? (Cp unchanged) Q would increase also

Q = m*Cp*ΔT • What if you had a smaller Cp? Q will be smaller

Q = m*Cp*ΔT • What if you had a greater temperature change? Q would be greater

Heat vs. Temperature Which has more heat. . . A spoonful of water at 100ºC or a bucketful of water at 100ºC?

Heat vs. Temperature Which has more heat. . . A spoonful of water at 100ºC or a bucketful of water at 100ºC? The bucketful, because it has more mass ! Heat is NOT the same as temperature!

Calorimetry Demo • In a calorimeter, usually you put something hot in water and measure the ΔT of water • The ΔT tells you the Q that left the hot substance (heat transfer) • Heat transfer is always from hot ---> cold