chap 15 key terms

Question 1

absolute temperature scale

Answer 1

Absolute temperature scale- The absolute temperature scale is measured in kelvin (T[K] = T[OC] + 273). The scale starts at absolute zero, the temperature at which atoms and molecules have minimum kinetic energy.

Question 2

absolute zero

Answer 2

Absolute zero- A temperature of -273OC or 0 K. Molecules and atoms have minimum kinetic energy at this temperature.

Question 3

enhanced greenhouse effect

Answer 3

Enhanced greenhouse effect- An increase in the temperature of Earths surface due to an increased concentration of greenhouse gases, as a result of human activities.

Question 4

gas constant

Answer 4

Gas constant- The constant, R, in the ideal gas equation pV = nRT, R = 8.31 J K-1 mol-1 when pressure is measured in kPa, volume in L and temperature in K.

Question 5

greenhouse gas

Answer 5

Greenhouse gas- A gas that is able to absorb and re-radiate heat radiation. Examples are carbon dioxide, methane and water vapour.

Question 6

greenhouse effect

Answer 6

Greenhouse effect- The warming of the Earths atmosphere due to the absorption of infrared radiation by gases such as carbon dioxide, water and methane.

Question 7

ideal gas

Answer 7

Ideal gas- A gas that obeys the gas equations at all temperatures and pressures.

Question 8

ideal gas constant

Answer 8

Ideal gas constant- A constant value denoted by the symbol R and equal to a value of 8.31 J K-1 mol-1. Used in the formula pV=nRT where pressure is measured in kPa, volume in L, amount in mol and temperature in K.

Question 9

ideal gas equation

Answer 9

Ideal gas equation- The equation that describes the behaviour of an ideal gas pV=nRT.

Question 10

kelvin scale

Answer 10

Kelvin scale- The absolute temperature scale is measured in kelvin (T (K) = T (OC) + 273).

Question 11

kinetic energy

Answer 11

Kinetic energy- The energy that a particle or body has due to its motion (KE = ½ mv2)

Question 12

kinetic molecular theory

Answer 12

Kinetic molecular theory- A theory that aims to explain the behaviour of gases by assuming gases are composed of a large number of particles in random motion; these particles move in straight lines and have elastic collisions. The gas particles are very small and there is no attraction between the particles. The average kinetic energy of the gas particles is related to the temperature of the gas.

Question 13

molar mass

Answer 13

Molar mass- The mass of 1 mole of a substance measured in g mol-1; symbol M.

Question 14

molar volume

Answer 14

Molar volume- The volume occupied by 1 mole of gas at a specified set of conditions. At standard temperature (0OC or 273 K) and pressure (100kPa), the molar volume of a gas is 22.7 L mol-1.

Question 15

partial pressure

Answer 15

Partial pressure- The pressure exerted by an individual gas in a mixture of gases. The total pressure is the sum of the partial pressures.

Question 16

pascal

Answer 16

Pascal- Unit of pressure equal to 1 newton per square metre (1 N m-2), where pressure = force/area.

Question 17

pressure

Answer 17

Pressure- A measure of a force exerted on a surface per unit area of the surface. Common units for gas pressure are Pa, kPa and atm.

Question 18

standard atmosphere

Answer 18

Standard atmosphere- One standard atmosphere (1 atm) is the pressure required to support 760 millilitres pf mercury (760 mmHg) in a mercury barometer at 25OC. One atmosphere pressure is approximately the pressure experienced at sea level.

Question 19

standard laboratory conditions (SLC)

Answer 19

Standard laboratory conditions (SLC)- Conditions of temperature and pressure relevant to gas, where the temperature is 298 K (25OC) and the pressure is 100 kPa.

Question 20

volume

Answer 20

Volume- The amount of space that a substance occupies. It can be calculated by multiplying length by width by depth of a regular solid. Otherwise, it can be determined by finding the volume of water displaced by the substance.