Chemistry Module 5 IQ1

What is the reaction involving the dehydration of cobalt chloride?

CoCl2.6(H2O) + heat <—> CoCl2 + 6H2O(g)

What colour is cobalt chloride when hydrated?

Pink

What colour is cobalt chloride when dehydrated?

Blue

What is the equation for the formation of the Iron (III) Thiocyanate Ion?

Fe(3+)(aq) + SCN(-)(aq) <—> [FeSCN](2+)(aq)

What colour is the Iron(III) ion?

Yellow

What colour is the SCN(-) ion?

Colourless

What colour is the [FeSCN](2+) ion?

Dark red

What is the equation for the combustion of magnesium?

2Mg(s) + O2(g) → 2MgO(s)

What is the equation for the combustion of steel wool?

4Fe(s) + 3O2(g) → 2Fe2O(s)

What is an open system?

A system which exchanges mass with its surroundings

What is a closed system?

A system which does not exchanges mass with its surroundings

What is static equilibrium?

Equilibrium where there is no conversion of reactants into products or vice versa

What is dynamic equilibrium?

Equilibrium where the rate of the forward reaction is equal to the rate of the reverse reaction, and there is no net change in the amount of reactants or products

State the second law of thermodynamics

• For a closed system with fixed internal energy, entropy is maximised at equilibrium

• For a closed system with fixed entropy, the total energy is minimised at equilibrium.

• Chemical systems will tend towards a state of maximum entropy and minimum enthalpy

When will a reaction go to completion?

When entropy increases and enthalpy decreases

This reaction is spontaneous

When will a reaction not occur?

When entropy decreases and enthalpy increases

This reaction is not spontaneous

When will a reaction reach equilibrium?

When both entropy and enthalpy increase or decrease

This reaction is reversible

What is Gibbs Free Energy?

A measure of the net result of the energy and entropy drives for a reaction

What is the equation for Gibbs Free Energy?

Change in GFE = Change in Enthalpy - (Temperature (K))(Change in Entropy)

When deltaG < 0

The reaction is spontaneous

When deltaG > 0

The reaction is not spontaneous

When deltaG = 0

The reaction is at equilibrium

What happens in a chemical reaction that reaches equilibrium? Produce a timeline

• High rate of collisions between reactants. The rate of forward reaction is high

• Concentration of reactants decrease and rate of collisions decrease. Rate of forward reaction decreases.

• Concentration of products increases. Rate of collisions increase and rate of reverse reaction increases.

• Rate of forward reaction becomes equal to the rate of the reverse reaction and dynamic equilibrium is reached

• Concentrations remain constant