Unit 1: Section 12- Acids and Bases + RP 9

Question 1

Define a Bronsted-Lowry acid

Answer 1

a substance that can donate a proton

Question 2

Define a Bronsted-Lowry base

Answer 2

a substance that can accept a proton

Question 3

What is the equation for calculating pH?

Answer 3

pH = log[H+]

Question 4

What does [H+] represent?

Answer 4

the concentration of the hydrogen ions in the solution

Question 5

Define strong acid

Answer 5

they fully dissociate

Question 6

What is a monoprotic acid?

Answer 6

an acid that donates one H+ ion or proton per every molecule when it dissociates with water

Question 7

How many d.p. values is pH given to?

Answer 7

2d.p.

Question 8

How do you rearrange the pH equation to find [H+]?

Answer 8

[H+] = 1 x 10 ^-pH

Question 9

What is the equilibrium equation that occurs in all aqueous solutions and pure water?

Answer 9

H2O (l) ⇌ H+ (aq) + OH- (aq)

Question 10

Why is Kw used and not Kc?

Answer 10

because [H2O (l)] is much bigger than the concentrations of the ions, we assume its value is constant and make a new value, Kw

Question 11

What is the Kw expression?

Answer 11

Kw = [H+ (aq)] [OH- (aq)]

Question 12

What type of compound are weak acids usually?

Answer 12

organic

Question 13

What type of compound are strong acids usually?

Answer 13

inorganic

Question 14

What is a diprotic acid?

Answer 14

donates two hydrogen ions (H2SO4), the [H+] is 2x that of the acid

Question 15

How can the Kw equation be rewritten for pure and neutral solutions?

Answer 15

Kw = ([H+])²
because [OH-] = [H+]

Question 16

What is the Kw value of an aqueous solution at room temp (25°C)?

Answer 16

1.0 x 10^-14 mol^2 dm^-6

Question 17

define strong base

Answer 17

they completely dissociate into their ions in solution

Question 18

How to calculate pH of strong base

Answer 18

1) use pH equation
2) use Kw equation
3) pH of a base = -log√Kw

Question 19

What is Kw?

Answer 19

the ionic product of water, 1.0 x 10^-14 mol^2 dm^-6

Question 20

Define weak acid

Answer 20

only partially dissociate into their ions in solution

Question 21

What is Ka?

Answer 21

the acid dissociation constant

Question 22

What does the size of the Ka value mean?

Answer 22

larger Ka= compounds that dissociate more completely into solution, stronger acids

smaller Ka= weaker acids

Question 23

What is the Ka equation?

Answer 23

Ka = [H+]² / [HA]initial

Question 24

What are the two key assumptions when using Ka to calculate the pH of weak acids?

Answer 24

1. that [H+] = [A-]
2. that conc of HA at equilibrium is the same as initial conc of the acid because of small dissociation

Question 25

What is the equation for converting pKa into Ka?

Answer 25

Ka = 10 ^-pKa

Question 26

What is pKa?

Answer 26

the negative logarithm of Ka

Question 27

What is the equivalence point?

Answer 27

the volume of one solution that exactly reacts with the volume of the other solution

Question 28

What is the end point of a titration?

Answer 28

when the indicator changes colour

Question 29

How to pick an indicator?

Answer 29

needs to be at the end point, in the vertical section of the curve