Chemistry Unit 3 Topic 1

What is the difference between an open and closed system?

In an open system, energy and mass can be exchanged with surroundings whereas, in a closed system, only energy can be exchanged with surroundings

What is dynamic equilibrium?

When the forward and reverse reactions are occurring at the same rate.

Can dynamic equilibrium occur in an open system?

No

In a reversible reaction, one reaction is exothermic and the other is endothermic. True or false

True

How do we find equilibrium in a graph?

When all the lines become flat/horizontal

What are the three factors that affect equilibrium?

Temperature, Concentration, and Pressure

If the temperature of a reaction is increased, what will happen to the position of the equilibrium?

The position of the equilibrium will shift to favour the endothermic reaction

If the pressure of a system is increased, what will happen to the position of the equilibrium?

The position of the equilibrium will shift to favour the reaction which produces the lowest amount of moles

What is Le Chatelier’s Principle?

If a system in equilibrium is subject to change, the system will act to partially oppose that change

Based on Le Chatelier’s principle, what will happen if there is an increase in the concentration of a species?

The reaction that uses this species as a reactant will be favoured

Based on Le Chatelier’s principle, what will happen if there is an increase in the pressure or decrease in volume (if gas species)?

The reaction that produces the fewest mols will be favoured

Based on Le Chatelier’s principle, what will happen if the solution is diluted or there is a decrease in the concentration (if aqueous species)?

The reaction that produces the most mols will be favoured

Based on Le Chatelier’s principle, what will happen if there is an increase in temperature?

The endothermic reaction will be favoured

What is a heterogenous system?

Not everything is in the same state

What is a homogenous system?

All reactants and products are in the same state

What is the only way to change the value of the equilibrium constant?

To change the temperature

If there are many more mols of products than reactants at equilibrium, Kc will be … ?

Very large

If there are many more mols of reactants than products at equilibrium, Kc will be … ?

Very small

If Kc is small, the forward reaction occurs at a lesser or greater extent?

Lesser

If Kc is very small, what can you assume?

That the initial concentration of the reactants is approx. equal to the concentration of reactants at equilibrium

The acid donates a hydrogen ion (proton) and the base receives a hydrogen ion. True or false

True

What is a polyprotic acid

It donates multiple protons

What is a monoprotic acid?

It donates one proton

Strong acids dissociate ….., while weak acids dissociate …...

Entirely, partially

What is conductivity in terms of acids and bases?

Strong acids and bases producing ions to a greater extent than weak acids and bases

Solutions with strong acids and bases are better … and have increased …

Electrolytes, conductivity

Kw is essentially the concentration of … multiplied together. The value of Kw at 25 degrees Celsius is …

the products, 1×10^-14

What is pH? An increase by 1 pH represents a … increase in the concentration of hydrogen ions.

How acidic or basic an aqueous solution is, ten times 

What do pH and pOH add up to?

14

What are conjugate acids and bases?

An acid donating a hydrogen ion, and a base accepting the hydrogen ion in the reverse reaction

What are amphiprotic species?

Species that can act as both an acid and a base

What is a buffer solution and what does it do?

A solution which contains a conjugate acid and its base (or vice versa) and resists changes in pH. When H+ concentration is increased the buffer will act as a base and accept hydrogen ions to partially oppose the change in accordance to Le Chatelier’s principle. Similarly, when H+ concentration is decreased, the buffer will act as an acid.

The equilibrium constant for an acid is Kb and the constant for a base is Ka. True or false

False

The higher the value of the constant, the greater the extent that the … reaction occurs, Thus, the higher the Ka or Kb value, the more the acid or base …. and the … it is.

Forwards, dissociates, stronger

Ka x Kb for conjugate acids and bases = ?

Kw

Name three strong acids

Hydrochloric acid (HCl), Nitric acid (HNO3), Sulphuric acid (H2SO4)

Name two weak acids

Carboxylic acids (eg.C2H4O2), Carbonic acids (H2CO3)

Name two strong bases

Group 1 hydroxides (eg. NaOH), Barium hydroxide (Ba(OH)2)

Name two weak bases

Ammonia (NH3), Amines (C3H7NO)