Section 3 Flashcards

A reaction in which thermal energy is transferred to the surroundings, causing the temperature of the surroundings to increase.

A reaction in which thermal energy is taken in from the surroundings, causing the temperature of the surroundings to decrease.

Endothermic, as energy is required to break chemical bonds.

Exothermic, as energy is released when new chemical bonds are formed.

\(Q = m \times c \times \Delta T\) (where \(m\) is the mass of the water or solution, \(c\) is the specific heat capacity, and ΔT is the temperature change).

\(\Delta H = -\frac{Q}{\text{moles}}\) (converted to kJ/mol by dividing \(Q\) by 1000).

A diagram showing reactants at a higher energy level than products, with a curve showing activation energy (\(E_{\text{a}}\)) and a negative enthalpy change (ΔH).

The minimum amount of energy that colliding particles must possess for a chemical reaction to occur.

Enthalpy change = total energy required to break bonds - total energy released when making bonds.

1. Particles must collide with energy greater than or equal to the activation energy. 2. Particles must collide with the correct orientation.

Particles gain kinetic energy and move faster, leading to more frequent collisions. A higher proportion of particles possess energy greater than or equal to the activation energy, leading to more successful collisions per second.

There are more reactant particles per unit volume, which increases the frequency of collisions, resulting in a higher rate of successful collisions per second.

More reactant particles are exposed at the surface, which increases the frequency of collisions, resulting in a higher rate of successful collisions per second.

It provides an alternative reaction pathway with a lower activation energy, so a higher proportion of collisions have energy greater than or equal to the activation energy.

No, it increases the rate of both the forward and reverse reactions equally, so equilibrium is reached faster but the position remains unchanged.

A state in a closed system where the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant.

A system in which no reactants or products can enter or escape.

If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.

The equilibrium position shifts to the side with fewer moles of gas to decrease the pressure.

The equilibrium position shifts in the direction of the endothermic reaction to absorb the added heat energy.

N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g)

A temperature of 450 degrees Celsius, a pressure of 200 atmospheres, and an iron catalyst.

The forward reaction is exothermic, so a lower temperature gives a higher yield. However, a higher temperature is used to ensure a sufficiently fast rate of reaction.

A higher pressure shifts the equilibrium to the right (fewer gas moles), increasing the yield of ammonia and the rate of reaction, but higher pressures are expensive and dangerous to maintain.

Solid ammonium chloride decomposes into ammonia and hydrogen chloride gases when heated (endothermic), and recombines into ammonium chloride when cooled (exothermic).