Gases and Temperature
Physical Science Guided Notes
➔ Charles’ Law: for a constant amount of gas at constant pressure, temperature of the gas and
volume of the gas will be directly proportional.
◆
Directly proportional
relationship: as one value increases, the other increases, and
vice versa.
◆
If a gas gets hotter, its
volume will tend to get bigger.
◆
If a gas gets cooler, its
volume will tend to get smaller.
◆
If the volume of a gas
expands, it’s temperature will go down.
◆ If the volume of a gas shrinks, it’s temperature will go up.
◆ Think of it kinetically: as particles have more energy, they
will hit the walls of its container more often, and harder.
◆ Heated air spreads out to increase volume of the balloon.
➔ We can represent Charles’ Law with this equation:
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 𝑉𝑉𝑉𝑉𝑉𝑉
=
𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉 𝑉𝑉𝑉𝑉𝑉𝑉
➔ T (both initial and final) must be not in degrees celsius, but in degrees kelvin (K).
◆ Named after William Thomson, 1st Baron Kelvin, call him Lord Kelvin.
◆ This temperature scale has zero degrees set at the coldest possible temperature,
absolute zero.
◆ As particles get cooler and cooler, they have move less and less, and temperature gets
lower and lower.
◆ Zero on the kelvin scale is where particles (theoretically) have no motion
◆ Calculating a kelvin value from a celsius value is easy! (Degrees kelvin are the same
size as degrees celsius, you see)
𝑉 = °𝑉 − 273.15
Physical Science Guided Notes
If a 15 cm3 balloon at 23 °C is heated to 50°C, what will it’s new volume be?
Ti =
Tf =
Vi =
Vf =
If a 15 cm3 balloon at 23 °C is compressed to 10 cm3, what will it’s new temperature be?
Vi =
Vf =
Ti =
Tf =
If a 0.5 L cylinder of gas is heat from 300 K to 430 K, what will be the new volume of the gas?
(assume the cylinder expands easily)
Vi =
Vf =
Ti =
Tf =
Physical Science Guided Notes
For the graph above, what will be the new temperature of 1250 cm3 at 15 K if it is compressed to
1000 cm3?