CH1 - Equilibria and acid base reactions

A substance that donates hydrogen ions during neutralisation reacts

e.g. HCl, HNO3, CH3COOH, H2SO4

HX (aq) ⇌ H+ (aq) + x- 

They are substances that accept hydrogen ions. They neutralise an acid, producing a salt

Not all bases are alkalis, all alkalis are bases

e.g. NaOH, KOH, NH3

The acidity of an aqueous solution depends on the number of H+ ions in solution

pH is related to [H+]

As [H+] increases, pH decreases

Concentration of [OH-] increases as [H+] decreases

Anything below 7 is acidic, above 7 is alkaline, 7 is neutral

Neutralisation occurs between acids and bases, including carbonates, metal oxides and alkalis.

It produces a neutral solution containing a salt and water

acid + base > salt + water

acid + carbonate > salt + water + carbon dioxide

acid + metal > salt + hydrogen

Strong acids fully dissociate in aqueous solution and have a low pH as the concentration of H+ is high

Weak acids partially dissociate in aqueous solution and have a higher pH than strong acids, but less than 7. They have a lower concentration of H+.

A reversible reactioncan go in either direction, both forward and reverse

Dynamic equilibrium is when the forward and reverse reactions occur at the same rate

The equilibrium constant is represented by Kc

General reaction: aA + bB ⇌ cC + dD 

[C]c[D]d (products)  / [B]b[A]a (reactants)

Large value of Kc shows there are more products than reactants

Value of less than one shows that there are more reactants than products

The proportion of products to reactants in an equilibrium mixture

It states that if a system at equilibrium is subjected to change, the equilibrium tends to shift to minimse the effect of change

Increasing the temperature of an endothermic reaction moves equilibrium to the right, but decreasing it moves equilibrium to the left.

Increasing the temperature of an exothermic reaction moves equilibrium to the left, but decreasing it moves equilibrium to the right.

If the concentration of A is increased, equilibrium will shift to the right to reduce the amount of A

If the concentration of A is reduced, equilibrium will shift to the left, increasing the amount of A

Increasing pressure results in equilibrium moving to the side with fewer moles

Decreasing pressure results in equilibrium moving to the side with more moles

It doesn't, there is no change in the position, equilibrium is just reached faster

-log[H+]

Pour one solution (acid) into a burette using a funnel. Remove the funnel and read burette

Use a pipette to add a measured volume of the other solution (base) into conical flask

Add a few drops of indicator to solution in the flask

Run the acid from the burette to the solution in the concical flask whilst swirling the flask

Stop when the indicator changes colour

Read burette again and substract from initial value to find volume of acid used

Repeat