🔥Heat and Temperature (DNF) Flashcards
Define heat capacity
the heat energy of an object that’s needed to change its temp. by 1K (1°C)
symbol = C (capital c)
unit = joules per kelvin (JK−1)
Define temperature
the measure of the hotness or coldness of a body
S.I. unit of temperature?
an S.I. unit is a unit that is used worldwide for measurement eg. second
kelvin (K)
273.15K = 0°C
Degrees - 273.15 = Kelvin
Define thermometric property
it is the physical property of a thermometer that changes measurably with temp.
ie. it allows us to measure temp.
name some thermometric properties
resistance of a wire, colour of liquid crystals, a gas, Emf of a thermocouple
explain how the Emf of a thermocouple can measure temperature
Emf drives current to flow (battery provides Emf)
- Two wires made of different metals (copper and constantan) are joined at both ends
*if these ends are at a different temp. then emf generated, - The size of the emf depends on the temp. difference between the ends of the wires => size of emf can be used to measure temp.
explain how the resisitance of a wire can measure temperature
- as the temperature of the wire increases, so does resistance of wire
- resistance depends on temperature => resistance can be used to measure temp.
explain how the colour of liquid crystals can be used to measure temperature
- Temperature changes affects the colour of a liquid crystal => can be used to measure temp.
eg. thermometer black = placed on someones forehead = change in colour
explain how a gas can be used to measure temp.
- as volume rises in gas, so does its temp. and pressure (at a fixed position = so that it won’t go up)
formula for heat capacity?
Q = CΔθ
Δθ = change in temperature ie. Final temp. - initial temp.
define specific heat capacity
it is the substance of heat energy needed to change the temp. of 1KG of that substance by 1K
ie. the amount of heat needed to raise a substances temp by 1K
What’s the symbol for specific heat capacity?
c (lowercase ‘c’)
what’s the unit of specific heat capacity?
joule per kilogram per kelvin =>
J kg-1K-1
What is the specific heat capacity formula?
Q = mc ∆θ
∆θ = (rise/fall in temperature)
Define latent heat
It is the heat energy needed to change state of matter without a change in temperature