chem exam 2 Flashcards

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1

acids are a proton ____

donor

2

bases are proton _____

acceptors

3

acids create conjugated ____

bases

4

bases create conjugated ____

acids

5

Equilibrium will always favor the

weaker acid

6

What is the conjugate base of formic acid, HCO2H?

HCO2 -

7

The equilibrium constant Kc for the following reaction is 1.29E-2 at 600K. What is Kp

COCl2 -> CO + Cl2

Kp=Kc(RT)change in n --> ((1.29E-2)(0.08205)(600))2-1

0.635

8

Student ran an experiment at 546K

COCl2 --> CO + Cl2

She introduced 0.844 moles of COCl2 into a 1l container. [Cl2] came to be3.66E-2. What is Kc?

Ice table.

0.844mol/1L=0.844

K = (3.66E-2)2/0.807

K=1.66E-3

9

If Kp is 1.57 at 600K, then: (T or F)

CO + Cl2 --> COCl2

COCl2 will be consumed

Kp increases

CO will be produced

Q > K

Reaction at equilibrium

all F

10

Name the acid, base, CA and CB in:

HCO3 - + H2O --> CO3 2- + H3O+

HCO3 - - acid

H2O - base

CO3 2- -CB

H3O+ - CA

11

If [H3O+] > [OH-]

acidic

12

If [H3O+] < [OH-]

basic

13

Calculate the pH of a 0.015M solution of NaOH at room temperature

[OH-] = 0.015M

pOH = -log[OH-] = -log(0.015) = 1.82

pH +pOH = 14 --> pH + 1.82 = 14 = 12.18

14

pH scale goes from 0 to 14 with 0 being ____ and 14 being ____

acidic/basic

15

a strong acid has a weak ___

CB

16

what groups on the periodic table do not affect pH

1 & 2

17

The pOH of an aqueous solution at 25 °C was found to be 8.80.
Calculate the H3O+ ion in the solution

pH + pOH = 14

pH = 14-8.80 = 5.2

[H3O+] = 10-pH = 10-5.2 = 6.31E-6

18

Lower pKa, ____ acid and ___ base

stronger acid/weaker base

19

Calculate the pH of a 0.396 M aqueous solution of hydrofluoric acid (HF, Ka= 7.2x10-4)

1.77

20

The pH of aqueous 0.510 M hypobromous acid, HBrO, is 4.45. What is the Ka of this acid?

2.5E-9

21

If Ka > Kb

acidic

22

If Kb > Ka

basic

23

Strong base with strong acid yields a

pH = 7

24

Weak Rxns to Completion acid with strong base yields

pH > 7

25

Weak base with strong acid yields

pH < 7

26

When 25 mL of 0.20 M hydrocyanic acid (HCN) and 25 mL of 0.20 M
potassium hydroxide (KOH) are combined, the pH of the resulting
solution will be

>7

27

A buffer solution is 0.376 M in HCN and 0.215 M in NaCN. If Kb for CN is 2.5x10-5, what is the pH of this buffer solution?

9.16

28

Which of the following aqueous solutions are good buffer systems?

A. 0.28 M ammonia + 0.14 M HCl
B. 0.29 M nitric acid + 0.21 M sodium nitrate
C. 0.35 M perchloric acid + 0.26 M sodium perchlorate
D. 0.12 M sodium hydroxide + 0.27 M sodium bromide

A

29

What mass of solid NaCH3CO2 (molar mass = 82.0 g/mol) should be added to 1.00 L of 0.423 M CH3CO2H to make a buffer with a pH of 4.74? (pKa of CH3CO2H = 4.74)

34.7

30

Determine the pH when 0.095 mol NaOH is added to 1.00 L of a buffer solution that is 0.369 M in HNO2 and 0.278 M in NO2 Ka = 4.5x10-4

3.48

31

An acid-base equilibrium system is created by dissolving 0.50 mol CH3CO2H in water to a volume of 1.0 L. What is the effect of adding 0.50 mol CH3CO2– (aq) to this solution?

1.The pH of the solution will equal 7.00 because equal concentrations of a weak acid and its conjugate base are present.
2. Some CH3CO2H(aq) will ionize, increasing the concentration of CH3CO2- (aq) and increasing the pH.
3. Some CH3CO2– (aq) will react with H3O+, increasing the concentration of CH3CO2H(aq) and reestablishing the solution equilibrium.

only 3

32

100 mL of 0.100 M acetic acid is titrated with 0.100 M NaOH. Calculate the pH at EP

8.72

33

EP of weak base and strong acid

pH is less than 7

34

EP of strong acid and strong base

pH is equal to 7

35

neutral + neutral =

neutral solution

36

acidic + basic =

neutral solution

37

acidic + neutral =

acidic

38

basic + neutral =

basic

39

strong acids

HClO4, HCl, HBr, HI, HNO3, H2SO4

40

strong bases

LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

41

A 45.4 mL sample of a 0.566 M aqueous nitrous acid solution is titrated with a 0.450 M aqueous sodium hydroxide solution. What is the pH after 39.8 mL of base have been added?

3.71

42

Ka for hypochlorous acid, HClO, is 3.50E-8.
Ka for acetylsalicylic acid (aspirin), HC9H7O4, is 3.00E-4.
Ka for formic acid, HCOOH, is 1.80E-4.

weakest acid?

HC9H7O4

43

All of the following compounds are acids containing chlorine. Which compound is the strongest acid?

HClO2
HClO3
HClO
HCl
HClO4

HClO4

44

Calculate the pH of a 0.392 M aqueous solution of diethylamine ((C2H5)2NH, Kb = 6.9E-4)

12.22

45

Indicate whether each of the following compounds will gave an acidic, basic or neutral solution when dissolved in water.

calcium perchlorate
ammonium bromide
sodium hypochlorite
2 sodium bromide
The pH will be less than 7.

2)The pH will be approximately equal to 7.

3)The pH will be greater than 7.

2

1

3

2

46

The anion NO2- is expected to be a stronger base than the anion NO3-.

true

47

An aqueous solution contains 0.35 M ammonium nitrate. One Liter of this solution could be converted into a buffer by the addition of: 0.17 1. 0.17 mol NaOH
2. 0.35 mol HI
3. 0.34 mol Ca(NO3)2
4. 0.34 mol NH3
5. 0.17 mol H

1

4

48

Which of the following statements are true regarding a 1.0 M solution of a strong acid (HA) at 25oC.

1. [A–] > [H3O+]

2. the pH = 0.00

3. [H3O+] = 1.0 M

4. [HA] = 1.0 M

2

3

49

If 0.50 L of a buffer containing 1.0 mol H2PO4– and 1.0 mol HPO42– is diluted to a volume of 5.0 L, the pH

decreases by 10.
remains unchanged.
increases by 1.
increases by 10.
decreases by 1.

unchanged

50

In the laboratory, a general chemistry student measured the pH of a 0.337 M aqueous solution of hydrofluoric acid to be 1.822.

Use the information she obtained to determine the Ka for this acid.

7.05E-4

51

The weaker the base . . .
The higher the pKa . . .
A functional buffer system has . . .
The Henderson Hasselbach equation can be used . . .
At the equivalence point of an acid titration with a base . . .
1) the stronger the conjugate acid
2) the weaker the acid
3) has a pH within 1 unit of the pKa of the weak acid
4) all of the acid has been converted to its conjugate base
5) to calculate the [base] to [acid] ratio in a buffer
6) half of the acid has been converted to its conjugate base
7) the weaker the conjugate acid
8) the stronger the acid
9) to compute the capacity of a buffer
10) equal concentrations of weak acid and conjugate base

1

2

3

5

4

52

A buffer solution contains 0.263 M ammonium chloride and 0.372 M ammonia (Kb of ammonia = 1.8E-5).

If 0.0470 moles of hydroiodic acid are added to 250 ml of this buffer, what is the pH of the resulting solution?

8.866

53

Which of the following statement(s) are TRUE regarding the half EP of the titration of a weak base with a strong acid?
1. The pH of the solution will equal the pKa.
2. The [base] will equal the [CA]
3. The volume of acid added is equal to the volume of initial base in the beaker

1

2

54

A 42.5 mL sample of 0.672 M HCO2H(aq) is titrated with 0.199 M KOH(aq). What is the pH at the equivalence point? (Ka of HCO2H = 1.8E-4

8.47

55

What is the pH of a solution that results from diluting 0.638 mol acetic acid (CH3CO2H) and 0.201 mol sodium acetate (NaCH3CO2) with water to a volume of 1.31 L? (Ka of CH3CO2H = 1.8E-5)

4.24