Week 4 Day 2 Acids Bases

Question 1

What is an acid?

Answer 1

molecule that donates an H⁺ in solution

or

increases H⁺ concentration when in aqueous solution

HA⇔H⁺ + A^-

**where A^- would be a conjugate base**

Question 2

What is a base?

Answer 2

molecule that accepts an H⁺ in solution

or

molecule that increases OH concentration when in aqueous solution

H⁺ + B ⇔ HB⁺

**where HB⁺ is a conjugate acid**

Question 3

Hydronium Ion

Answer 3

H₃O⁺

Question 4

Strong acids _______ ionize in solution.

Answer 4

fully ionize (essentially all of the molecular species dissociate into ions)

i.e.

HCl → H⁺ + Cl^-

or

HCl + H₂0 → H₃0⁺ + Cl^-

**where HCl is the strong acid**

Question 5

Weak acids ______ ionize in solution.

Answer 5

partially

Some molecules dissociate, and some do not.

Question 6

INFO CARD

Example and explanation of conjugate bases and pairs

Answer 6

HCl is an acid and wants to give away its H+ ion. There is nothing else in the solution, so the only available base is H2O. Therefore, water in this case behaves as a base and accepts the proton from HCl. In this process, water is converted its conjugate acid, H30+, and HCl is converted into its conjugate base, Cl-.

Question 7

Examples of bases

Answer 7

NaOH - sodium hydroxide

NH_{3 -} ammonia

Question 8

Examples of acids

Answer 8

HCl - hydrochloric acid

H2SO4 - sulfuric acid

H3PO4 - phosphoric acid

CH3COOH - acetic acid

Question 9

What does Le Chatelier’s Principle state?

Answer 9

If a system at equilibrium is disturbed so that the ratio of products to reactants no longer equals the equilibrium constant, it will react so as to reestabilsh the equilibrium state.

K_eq = generic equilibrium contant

Question 10

Can something have a -pH?

Answer 10

yes

pH = -log[H⁺] or10^-pH = H⁺

if H⁺ = 2, then pH = -0.3

Question 11

Henderson-Hasselbalch equation

Answer 11

pH = pK_a + log([A^-] / [HA])

HA ⇔ H⁺ + A^-

**where HA is the acid, and A^- is the conjugate base**

Question 12

Strong acids include…

Answer 12

H2SO4 - sulfuric acid

HI - hydroiodic acid

HBr - hydrobromic acid

HCl - hydrochloric acid

HNO3 - nitric acid

**Most other acids are weak acids!**

**Note: When a strong acid dissolves in water, it dissociates completely. This reaction goes to completion and is not an equilibriating process.**

Question 13

The equilibrium constant (K) is often applied with a subscript. The subscript denotes the type of equilibrium reaction.

K_{<strong>a</strong>} is the equilibrium constant for which kind of reaction?

Answer 13

the ionization of weak acids

also stated…

K_a is a measure of the acid’s strength

Question 14

Acid-base regulation

Relationship of CO₂, H₂O, H+, HCO₃^-, and H₂CO₃

Answer 14

Question 15

In regards to the value of K (equilibrium constant), fill in the blanks.

As K increases (K>1), the reaction tends to favor ________.

As K decreases (K<1), the reaction tends to favor ________.

Answer 15

products; reactants

*K > 1 means that the forward reaction becomes more favorable*

*K < 1 means that the reverse reaction becomes more favorable*

Question 16

INFO CARD

Conjugates acids and bases simplifed

Answer 16

acid → H⁺ + conjugate base

base + H⁺ → conjugate acid

Question 17

The most common nonmetal oxide in physiology

Answer 17

carbon dioxide

Question 18

A buffer is a solution that contains a weak acid and its conjugate base.

Describe 3 additional characteristics of a buffer.

Answer 18

A buffer solution resists changes in pH

The weak acid absorbs any added strong base.

The weak base absorbs any added strong acid.

Question 19

T or F: K_eq is temperature dependent.

Answer 19

True

Question 20

INFO Card: memorize this formula

Answer 20

CO₂ + H₂O ⇔ H⁺ +HCO₃^-

pH = 6.1 + log ([HCO₃^-] / .03 * PCO₂])