Deck 7

Question 1

Hess’law

Answer 1

Hess’law states that, if a reaction can take place by more than one route and the initial and final conditions are the same, the total enthlpy change is the same for each route.

Question 2

An enthalpy cycle

Answer 2

Is a diagram showing alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess’law.

Question 3

The rate of reaction

Answer 3

The rate of reaction is the change in concentration of a reactant or a product in a given time.

Question 4

Heterogeneous catalysis

Answer 4

Is catalysis of a reaction in which the catalyst has a different physical state from the reactants; frequently, reactants are gases whilst the catalyst is a solid.

Question 5

Homogeneous catalysis

Answer 5

Homogeneous catalysis is catalysis of a reaction in which the catalyst and reactants are in the same physical state, which is most frequently the aqueous or gaseous state.

Question 6

The Boltzmann distribution

Answer 6

The Boltzmann distribution is the distribution of energies of molecules at a particular temperature, often shown as a graph.

Question 7

le Chatelier’s principle

Answer 7

le Chatelier’s principle states that when a system in dynamic equilibrium is subjected to a change, the position of equilbirum will shift to minimise the change.

Question 8

Dynamic equlibrium

Answer 8

Dynamic equilibrium is the equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction.

Question 9

The greenhouse effect

Answer 9

The greenhouse effect is the process in which the absorption and subsequent emission of infrared radiation by atmoshperic gases warms the lower atmosphere and the planets surface.

Question 10

The troposphere

Answer 10

The troposphere is the lowest layer of the Earth’s atmosphere, extending from the Earth’s surface up to about 7km (above the poles) and to about 20Km(above the tropics).

Question 11

The stratosphere

Answer 11

The stratosphere is the second layer of the Earth’s atmosphere, containing the “ozoner layer”, about 10km to 50km above the Earth’s surface.

Question 12

Adsorption

Answer 12

Adsorption is the process that occurs when a gas, liquid or solute is held to the surface of a solid or, more rarely, a liquid.