Chapter 15: Acids and Bases

Question 1

How do you tell if a compound is an acid or a base?

Answer 1

Acids tend to start with H or end with COOH. Memorize strong acids.

Strong bases contain a metal cation and OH. Weak bases contain nitrogen. **Not all things ending with OH are bases. Always categorize acids first.

Question 2

What is an Arrhenius acid?

Answer 2

It is a substance that when dissolved in water increases the concentration of the hydronium ion.

Question 3

What is an Arrhenius base?

Answer 3

It is a substance that when dissolved in water increases the concentration of the hydroxide ion.

Question 4

What does an acid or base have to do in water in order to be considered a strong acid or base?

Answer 4

The acid or base must fully dissociate in water, leaving nothing but charged particles in the water.

Question 5

What is a weak acid or base?

Answer 5

The acid or base does not fully dissociate in water and although it does partially dissolve, the end result is hydronium ions or hydroxide ions, but also a large molecule.

Question 6

What is a Bronsted-Lowry acid?

Answer 6

It is a species that donates protons to another species/

Question 7

What is a Bronsted-Lowry base?

Answer 7

It is a species that accepts protons from another species.

Question 8

What is a conjugate acid-base pair?

Answer 8

It is a pair of species, one an acid, and the other a base, which differ only by the loss or gain of a proton.

Question 9

What is an amphiprotic species?

Answer 9

It is a species that can act as either an acid or a base depending on the other species involved in the reaction. Water is a great example of an amphiprotic substance.

Question 10

What is a Lewis Acid?

Answer 10

A species that forms a covalent bond by accepting an electron pair from another species.

Question 11

What is a Lewis Base?

Answer 11

A species that forms a covalent bond by donating an electron pair to another species.

Question 12

How do you know which way a reaction is going to go (left or right) based on acid strength?

Answer 12

Strong acids have weak conjugate bases, so it is highly unlikely that the reaction will go in the direction towards a strong acid. Instead it will go towards the conjugate base.

Question 13

How do you determine from a list of acids, how strong each acid is compared to the others?

Answer 13

Look at the electronegativity and the solubility in water of each acid. The more electronegative a dipole moment is, the easier the acid will break down into ions, thus making more electronegative elements stronger acids. If acids are close in strength, then see which one is more soluble in water because that also helps determine how effective and strong an acid is.

Question 14

How do you determine if products or reactants are favored in an acid-base reaction?

Answer 14

Figure out the conjugate acid-base pairs. From there, see which side has the stronger acid and base. Stronger base and acid makes that side favored.

Question 15

How does the polarity of bonds affect acid strength?

Answer 15

The larger the dipole moment between H—-X, the easier it is to remove protons, the stronger the acid is.

Question 16

How does the strength of the bond affect acid strength?

Answer 16

The size of X in H—–X increases as you travel down the periodic table. The bigger the X, the weaker the bond strength, and thus the stronger the acid.

Question 17

What are oxoacids and how do you determine their strength?

Answer 17

Oxoacids are like acids, but also have an oxygen atom in there H—–O—–Y. The strength of the oxoacid is associated with moving down the periodic table. The farther down you go, the larger the Y, the weaker the dipole moment and bond strength, meaning the weaker the oxoacid.

Question 18

What are oxyacids and how do you determine their strength compared to one another?

Answer 18

Oxyacids are just like oxoacids, but they have multiple oxygen atoms attached. The more oxygen an oxyacid has, the stronger it is as an acid.

Question 19

What are polyprotic acids and how do you know how strong they are?

Answer 19

They are acids that can have multiple protons removed , subsequently dissociating better, but the more protons that are removed ((-) goes up), the weaker the acid becomes.

Question 20

What is the autoionization of water? What is the ion product constant and how does it relate to self-ionization?

Answer 20

Water will ionize with itself and form protons and hydroxide ions. The ion product constant is the equilibrium concentrations of hydronium and hydroxide ions. It is highly dependent on temperature.

Question 21

In an ion equilibrium problem, what do know if you know the concentration of a strong acid or base?

Answer 21

You know the concentration of hydronium or hydroxide ions.

Question 22

If there is more than one strong acid or strong base in an ion equilibrium problem, what do you do?

Answer 22

You add up the concentrations of each strong acid or base to find the concentrations of hydronium or hydroxide ions.

Question 23

What is the solution if H+ is >1.0*10^-7?

Answer 23

The solution will be acidic.

Question 24

What is the solution if H+ is =1.0*10^-7?

Answer 24

The solution will be neutral.

Question 25

What is the solution if H+ is

Answer 25

The solution will be basic.

Question 26

If a strong acid or base produces more than 1 ion, how does that affect the concentration?

Answer 26

The concentration is multiplied by n, where n is the number of ions produced, which will rapidly increase the concentration of hydronium or hydroxide ions.

Question 27

How do you find the pH of a solution if you have the hydronium ion concentration? The pOH? The OH- concentration if you are not given the ion equilibrium constant?

Answer 27

pH = -log(H3O+)

pH + pOH = 14

[OH-] = 10^(-pOH)

Question 28

How many significant figures do you use in ion concentration and pH problems?

Answer 28

After the decimal point of a pH number, you use how ever many decimals are there. Typically, the concentrations are rounded to 2 significant figures and pH is normally kept at 3 significant figures.