weak and strong acids

What is an acid

A substance that forms aqueous solutions with pH of less than seven. Reason because they ionise in aqueous solutions to release hydrogen ions which just means they split or dissociate into their ions

What is ph

The measure of the concentration of hydrogen ions in the solution

Give examples of strong acids and their equations 3

Hydrochloric acid

Nitric acid

Sulferic acid

HCl - H+. + Cl-

HNO3 - H+. + NO3

H2SO4

What is a strong acid

An acid which completely ionises(dissociates) in an aqueous solution.(to release hydrogen ions)

What is a weak acid

An acid which only partially ionises(dissociates) in an aqueous solution.(to form hydrogen ions)

Which category of acids are weak acids and give examples in it

Carboxylic acids

Example ethanoic acid , citric acid , carbonic acid

Why do only a small portion of acid particles don’t fully dissociate to form hydrogen ions in weak acids

because the ionisation of a weak acid is reversible

Which means there is an equilibrium between the undissociated and the dissociated forms of the acid

Give an example of a reversible reaction ethanoic acid state why it’s reversible

CH3COOH—> H+ + CH3COO-

<—

Because it has a double arrow it shows the reaction is reversible

Give definition of a reversible reaction

As well as the reactants being able to form the products , the products can react to form the reactants

Basically the reaction can go both forwards and backwards

Why do we say that the equilibrium lies on the left?

Because only a few of the acid particles actually dissociate we say that it lies on the left which mean at equilibrium would have far more molecules of undissociated acid than it will dissociated acid

Is the ionisation/dissociation of strong acids reversible?

No

Is the ionisation/dissociation of weak acids reversible?

Yes it is a reversible reaction

Why are strong acids more reactive than weak acids?

Strong acids have greater concentration of H⁺ ions, so more of them will react a given amount of time.

This increases the rate of reaction

What is a good indicator to use for a titration between a strong acid and a weak alkali?

Methyl Orange.

Each time the pH increases by 1, how much does the H⁺concentration change by?

For each increase by 1 on the pH scale, the concentration of H⁺ ions gets 10x lower.

For each decrease by 1 on the pH scale, the concentration of H+ ions gets 10x higher.

(remember low pH is acidic - and acidic solutions have a high concentration of H+ ions)

What does acid strength mean

Strength is about how much an acid dissociates( what proportion of acid molecules ionise in water )

What is concentration

A measure of how much acid there is in a certain volume

With a more concentrated solution containing more acid per unit volume so it’s possible to get a strong acid at both a high and low concentration just like a weak acid can either be concentrated or dilute