Chem 116 Exam 3 WVU

HCl

Hydrochloric acid. A strong acid

HBr

Hydrobromic acid. A strong acid

HI

Hydroiodic acid. A strong acid

HNO3

Nitric acid. A strong acid

H2SO4

Sulfuric acid. A strong acid

HClO3

Chloric acid. A strong acid

HClO4

Perchloric acid. a strong acid

The conjugate base of a strong acid is acidic, basic, or neutral?

Neutral

The conjugate acid of a strong base is acidic, basic, or neutral?

Neutral

The conjugate base of a weak acid is acidic, basic, or neutral?

Basic

The conjugate acid of a weak base is acidic, basic, or neutral?

Acidic

Strong bases..

• Have a pH over 7

• Include OH group along with a metal from group 1

When a weak acid + a conjugate base are added, what happens to the pH?

pH of the solution increases

When a weak base + a conjugate acid is added, what happens to the pH?

pH of the solution decreases

What happens when H+ is added and a weak acid is produced? Is the solution basic, neutral, or acidic?

The solution is basic

What happens when H+ is added and a strong acid and strong base are produced?

The solution is neutral

What happens when H+ is added and a weak base is produced? Is the solution basic, neutral, or acidic?

The solution is acidic

Oxygen atoms and central nonmetal electronegative atoms are..

Acidic

Compounds including NH..

Are often weak bases

If given Kb and are solving for pH..

Subtract from 14 to find pH

When a strong acid is added to a buffer, what will react?

The conjugate base will react

When a strong base is added to a buffer, what will react?

The weak acid reacts

For a weak acid and a strong base to be considered a buffer..

There must be a lower concentration of the strong base

For a weak base and a strong acid to be considered a buffer..

There must be a lower concentration of the strong acid

Weak acids and a conjugate base OR weak bases and conjugate acids..

Are considered buffers

What is the equivalence point for a strong base and strong acid?

pH = 7

What is the equivalence point for a weak acid and a strong base?

pH is over 7

What is the equivalence point for a strong acid and weak base?

pH is less than 7

At pH = pKa..

The indicator is halfway through its color change. It’s 50% base and 50% acid

When an ion already present in a solution is added, what happens to solubility?

Solubility decreases

If a substance reacts with H+..

It’s solubility increases and it’s pH decreases

What’s a conjugate base?

When an acid donates H+, what’s left on the products side is its conjugate base.

What’s a conjugate acid?

When a base accepts H+, it becomes its conjugate acid

Which equation do you use to find acid or base disassociation constants?

Kw = (Ka)(Kb)

A solution is prepared by adding 0.10 mol of sodium fluoride, NaF, to 1.00 L of water. Will the solution be basic, acidic, or neutral?

• Basic because OH will be produced in the reaction

• F + H2​O⇌ HF + OH−

How do you find pH if given the Ka or Kb?

1. Find either Ka or Kb, depending on which one is not given

2. Do equilibrium problem with ICE table and algebra

3. Calculate pH by taking the -log of whatever answer you got in step 2

4. Subtract from 14 if you found the answer using Kb

How do you find pH if given the [H] or [OH]?

1. Find the pOH by doing -log[H] or -log[OH]

2. If given [OH], Find pH by doing 14 - (-log[OH])

How do you find the pH of a buffer?

1. Take the -log of Ka or Kb, depending on if the buffer is basic or acidic

2. Divide the molarity of the base by the molarity of the acid

3. Add the answers from step 1 and 2 together

4. Subtract final answer from 14 if dealing with a weak base

Which equation do you use to find the moles of a substance if given the volume and molarity?

Number of moles = Molarity x Volume

A smaller Ka..

Means the substances is stronger and less likely to dissolve

If pH < pKa..

Acidic color dominates

If pH > pKa..

Basic color dominates

How do you find pKa from Ka or Ka from pKa?

• Ka = 10^-pKa

• pKa = -log(Ka)