Chapter 18: Aqueous Ionic Equilibrium

What is the initial effect of ethylene glycol in antifreeze?

It causes drunkenness.

What condition is caused by an excess of acid in the body?

Acidosis.

Why is glycolic acid considered toxic?

It can overwhelm the buffering ability of HCO₃ in blood, causing blood pH to drop, low pH compromises ability to carry O2

What treatment is given for ethylene glycol poisoning?

Ethyl alcohol, which has a high affinity for the enzyme that metabolizes ethylene glycol.

What is a buffer?

An aqueous solution containing substances that prevent major changes in pH when small amounts of acid or base are added.

what are buffers typically composed of?

weak acid and conjugate base

What are the two active components of a buffer?

1) A substance to react with and remove added base; 2) A substance to react with and remove added acid.

What happens when a base is added to a buffer?

The added OH⁻ reacts with H₃O⁺ producing water, shifting equilibrium right/to produce more H₃O⁺

What occurs when an acid is added to a buffer?

The added H₃O⁺ increases the overall amount of H₃O⁺, shifting equilibrium to left/consume excess H₃O⁺.

If a strong base is added to an acidic buffer solution, how is it neutralized?

By the weak acid in the buffer

If a strong acid is added to an acidic buffer solution, how is it neutralized?

Neutralized by conjugate base

How do buffers work when theres an addition of base?

Buffers contain lots of weak acids (HA), they react with added base to neutralize

HA(aq)+OH- -> A-(aq)+H2O(l)

How do buffers work when theres an addition of acid?

Buffers contain lots of conjugate base anion (A-), ions combine with added acid to make more HA

H+(aq)+A- -> HA(aq)

what is the common ion effect?

in weak acid solution, adding salt containing anion NaA (Conjugate base of acid+common ion) shifts equilibrium left

what are basic buffers?

composed of weak base and its conjugate acid, usually in form of salt

What is buffer capacity?

The amount of acid or base a buffer can neutralize without causing a major pH change.

what is buffer range?

pH range in which buffer can be effective

what is the most effective buffer ratio?

[Base] : [Acid] = 1

0.1 < [base] : [acid]

True or false, when choosing which acid to make buffer with, choose one whose pKa is closest to pH of buffer

True, pKa + or - 1

what are acid base titrations?

basic solution of unknown concentration reacts with acidic solution of known concentration, vice versa

What is a titration curve?

pH vs amount of added titrant

How many equivalence points are for titration of polyprotic acid?

If Ka1 >> Ka2, then there are 2

What is the solubility product (Ksp)?

The equilibrium constant for the dissociation of solid salt into aqueous ions

What is the effect of the common ion on solubility?

Adding a salt with a common ion decreases the solubility of an insoluble salt.

What is molar solubility?

The number of moles of solute that will dissolve in a liter of solution.

How does pH affect the solubility of insoluble ionic hydroxides?

Increasing pH, decreases solubility and increases [OH]

What happens to the solubility of ionic compounds containing anions of weak acids when pH decreases?

Their solubility increases.

What is the equivalence point in a titration?

The point when the number of moles of acid equals the number of moles of base.

What is the significance of the ratio of [base] to [acid] in a buffer?

As the ratio approaches 1, the ability to neutralize improves.

What is the effect of adding a strong base to an acidic buffer?

It is neutralized by the weak acid present in the buffer.

What is the effect of adding a strong acid to a basic buffer?

It is neutralized by the conjugate base present in the buffer.

What is the role of indicators in titrations?

Indicators signal the endpoint of the titration by changing color.