Unit B - Gases

Question 1

What is pressure?

Answer 1

Measurement of force per unit area.

Question 2

What is the formula for Boyle’s Law?

Answer 2

P1V1 = P2V2

P1 = initial pressure (kPA)
P2 = final pressure (kPA)
V1 = initial volume (L)
V2 = final volume (L)

Question 3

What is absolute zero?

Answer 3

If a gas was cooled down sufficiently, the gas particles would lose all of their kinetic energy and their motion would then stop.

The lowest possible temperature that can be attained, it is the temperature at which all molecular motion stops.

Question 4

What is the formula for Charles’ Law?

Answer 4

V1 / T1 = V2 / T2

V1 = initial volume (L)
V2 = final volume (L)
T1 = initial temperature (K)
T2 = final temperature (K)

Question 5

What is the formula for Combined Gas Law?

Answer 5

P1 V1 / T1 = P2 V2 / T2

P1 = initial pressure (kPA)
V1 = initial volume (L)
T1 = initial temperature (K)

P2 = initial pressure (kPA)
V2 = final volume (L)
T2 = final temperature (K)

Question 6

What is the kinetic molecular theory?

Answer 6

It is when the motion of molecules is different for solids, liquids, and gases.

Question 7

Can you explain various properties of gases using the kinetic molecular theory?

Answer 7

Translational - motion (straight line)
Rotational - motion (turning or spinning)
Vibrational - motion (back or oscillating)

Question 8

What is the Law of Combining Volumes?

Answer 8

When measured at the same temperature and pressure, volume of gaseous reactants and products of chemical reactions are always in simple ratios of whole numbers.

Question 9

What is Avogadro’s Law?

Answer 9

Equal volume of gases at the same temperature and pressure contain equal numbers of molecules.

Question 10

What is the formula for Molar Volume?

Answer 10

N = V / Vm

Question 11

What is an ideal gas?

Answer 11

A hypothetical gas that obeys all the gas laws perfectly.

A gas which is speculative and they ob all the gas laws perfectly.

Question 12

What are some differences between an ideal gas and a real gas?

Answer 12

Ideal Gas - doesn’t condense assumes particles have no volume and are not attracted to each other.

• Molecules collide like perfectly hard spheres and rebound very quickly after collision. No energy is lost.
• Does not condense when cooled.
• Follows all gas laws perfectly under all conditions.
• Assumes that the particles have no volume and are not attracted to each other.

Real Gas - Collision takes longer, particles are attracted to each other and have volume, condenses to liquid or sometimes solid when cooled or under pressure.

• The molecules are “soft” (can be deformed) and intermolecular attractions are important.
• Condenses to liquid or sometimes solid when cooled or under pressure.
• Particles are attracted to each other and have volume.
• Behaves like an ideal gas was a higher temperature and lower pressures.

Question 13

Under what conditions do real gases behave least like ideal gases?

Answer 13

Real gases behave LEAST like ideal gases at low temperature and high pressure.

Question 14

What is the formula for ideal gas law?

Answer 14

PV = nRT

Question 15

What is partial pressure?

Answer 15

In a mixture of gases that do not react chemically, the total pressure is the sum of the partial pressures of each individual gas.

Question 16

Under what conditions do real gases behave most like ideal gases?

Answer 16

Real gases behave the MOST like ideal gases at high temperature and low pressure.