Buffers and pH

What happens when the equilibrium reaction between ethanoate acid and water occurs?

The ethanoic acid is only slightly dissociated, leaving large amounts of undissociated ethanoic acid molecules, called a large reservoir of ethanoate acid.

What are the natural occurring buffers in the body?

The hydrogen/hydrogencarbonate buffer system (CO22-/HCO3-) and amino acids existing as a zwitterions and having the ability to accept or give up H plus ions to maintain the pH.

What happens when a small amount of base is added to an acid buffer

1. The OH- ions combine with the H+ ions to form water. 2. This causes a shift in equilibrium to the right, and a little more acid dissociates into ions. 3. But because of the relatively high concentration of the added base, the ratio of base to acid changes very little, and therefore the pH of the solution is maintained.

What happens when a small amount of acid is added to an acid buffer?

1. The excess H+ ions combine with the ethanoate ion 2. This causing a shift in equilibrium to the left as more undissociated acid is formed. 3. But because of the relatively high concentration of the added base, the ratio of base to acid changes very little hence the pH of the solution is maintained

What is an acid buffer?

An acid buffer consists of a weak acid (e.g. ethanoic acid) and its conjugate base - the salt of the weak acid. (e.g. sodium ethanoate).

What is the pH value of a basic buffer usually? Give an example of a basic buffer system.

It is usually between 8 and 10. Ammonia and ammonium chloride. The ammonia does not ionize completely in the aqueous solution leaving a large reservoir of unprotonated (unionized) ammonia molecule. The ammonium chloride salt dissociates completely in aqueous solutions producing a large reservoir of the ammonium ion.

What are buffers?

A buffer is a solution that resists a change of pH when small amounts of base or acid is added to it.

What is a buffer solution?

A buffer solution, is a solution having the ability to maintain its pH value whenever small amounts of acid or base is added to it.

How can a buffer be made more effective?

By increasing the concentration of both the acid and the conjugate base (salt).

What does sodium ethanoate ionize to produce?

It completely disassociates in aqueous solution resulting in a large reservoir of ethanoate ions.

What happens when you add small amounts base or acid to a basic buffer?

Th OH ions combine with the positive ion to form for example ammonia and water, this causes a shift to the left in the equilibrium. For acids the H+ ions combine with the OH- ions to form water

What is the pH of an acid buffer? What does this relate to the name "acid buffer"?

The pH of an acid buffer is less than 7, usually between 4 and 6. It is this pH value that resulted in the name acid buffer, as substances with a pH less than 7 are deemed acidic.

What happens when you add small amounts base to a basic buffer?

There is an increase in the concentration of OH- ions. This results in a shift in the equilibrium of the reaction to the left. The excess OH- are removed due to the formation of more undissociated ammonia, this therefore maintains the pH of the solution

What are Basic buffers?

These consists of a weak base and its conjugate acid (salt).

Where are synthetic buffers produced and what are the two types?

They are produced in a laboratory and the two types are Acid Buffers and Basic Buffers.

What do naturally occurring buffers in the body do?

They ensure the pH of the body remains constant.