Gas Laws 2

What is pressure?

Force per unit area.

What causes gas pressure?

Force exerted by gas molecules hitting surfaces.

What instruments measure pressure?

Mercury barometer, aneroid barometer, Bourdon gauge.

What does the height of the mercury column indicate?

Downward force of atmospheric pressure.

What equilibrates with atmospheric pressure in a mercury barometer?

Weight of the mercury column.

What is an aneroid barometer?

A mechanical pressure gauge with a sealed evacuated metal box and flexible spring.

How does an aneroid barometer work?

External pressure compresses the container, rotating gears to display pressure.

What does a Bourdon gauge measure?

Gas pressure.

How does a Bourdon gauge work?

Pressure straightens a coiled tube, moving a gear mechanism and indicator needle.

1 atm equals how many mmHg?

760 mmHg.

1 atm equals how many PSI?

14.7 psi

1 mmHg = how many cmH₂O?

1.36 cmH₂O.

1 PSI = how many cmH₂O?

70.34 cmH₂O.

What primarily influences evaporation?

Temperature.

What happens when water is heated?

Increased kinetic activity → molecules escape surface tension → increased vapor pressure.

What is vaporization?

Change of liquid into gas; includes evaporation and boiling.

What is condensation?

Opposite of evaporation; warm vapor cools and becomes liquid.

What is water vapor pressure?

Kinetic activity of water molecules in air.

What is water vapor content?

Actual amount of water vapor in air.

What is thermal equilibrium?

Heat moves from higher temp to lower until equal.

Three methods of heat transfer?

Conduction, convection, radiation.

What is heat capacity?

Calories needed to raise 1 g of a substance by 1°C.

What is absolute humidity?

Actual weight of water vapor in air (mg/L)

What is absolute humidity in the lungs at 37°C?

43.8 mg/L.

What is relative humidity?

Ratio of actual water vapor to maximum capacity at that temperature.

Water vapor content at body temp?

44 mg/L.

Water vapor pressure at body temp?

47 mmHg

What is STPD?

0°C, 760 mmHg, dry.

What is BTPS?

37°C, 760 mmHg, saturated.

What is cohesion?

Attraction between like molecules; forms convex meniscus.

What is adhesion?

Attraction between unlike molecules; forms concave meniscus.

How does temperature affect surface tension?

Surface tension varies inversely with temperature.

Laplace's Law?

P=2T/r

What is molar volume at STPD?

22.4 L.

Density formula?

GMW ÷ 22.4 L.

Which is heavier: O₂ (32) or He (4)?

O₂.

Partial pressure of O₂ at 21%?

760 × 0.21 = 159.6 mmHg.

What does Dalton's Law state?

Total pressure = sum of partial pressures.

Boyle's Law?

P₁V₁ = P₂V₂ (inverse relationship).

Charles' Law?

V1/T1=V2/T2

Gay‑Lussac's Law?

P1/T1=P2/T2

Graham's Law?

Rate1/Rate2 = √(M2/M1)

What is diffusion?

Movement from high concentration to low.

Henry's Law?

C=kP