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Home / Find the Ph of a 0.32 M Ethylamine C2h5nh2 Solution

Find the Ph of a 0.32 M Ethylamine C2h5nh2 Solution

Northrup's Chem 112 Section TTU General Chemistry

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Chem 1120 - Chapter 16: Acid-Base Equilibria
Practice Quiz 3

1. Calculate the [H3O+] in 0.010 M HOCl solution. Ka = 3.5 x 10-8.

a) 1.9 x 10-5 M
b) 3.6 x 10-5 M
c) 5.8 x 10-5 M
d) 4.0 x 10-6 M
e) 7.2 x 10-6 M

2. The reaction that occurs when NH4Br dissolves in water is __________.

a) NH4 + + OH- <----> NH4OH
b) Br- + H3O+ <----> HBr + H2O
c) NH3 + H2O <----> NH4 + + OH-
d) NH4 + + H2O <----> NH3 + H3O+
e) Br-- + H2O <----> HBr + OH-

3. A 0.10 M solution of which of the following salts is MOST basic?

a) NH4F
b) NH4NO2
c) NH4CH3COO
d) NH4OCl
e) NH4CN

4. In the laboratory, a general chemistry student measured the pH of a 0.599 M aqueous solution of ethylamine, C2H5NH2 (a weak base), to be 12.192. Use the information she obtained to determine the Kb for this base.

a) 2.41 x 10-11
b) 10-1.88
c) 4.15 x 10-4
d) 1.56 x 10-2

5. The pOH of an aqueous solution of 0.500 M trimethylamine (a weak base, Kb = 6.3 x 10-5) with the formula (CH3)3N) is:

a) 9.8
b) 7
c) 4.2
d) 2.25
e) less than 1

6. What is the [H3O+] of a solution that is 0.0100 M in HNO2 (Ka = 4.5 x 10-4 ) and 0.0100 M in NaNO2?

a) 2.14 x 10-4 M
b) 1.45 x 10-4 M
c) 7.41 x 10-4 M
d) 4.5 x 10-4 M
e) 1.17 x 10-4 M

7. When a weak acid is titrated with a strong base, the pH at the equivalence point is ALWAYS __________.

a) 7
b) < 7
c) > 7
d) < 1
e) > 4

8. Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.10 M HF and 200. mL of 0.10 M KF.

a) 2.82
b) 2.96
c) 3.32
d) 3.44
e) 3.53

9. If 0.040 moles of solid NaOH is added to 1.0 liter of a solution that is 0.10 M in NH3 and 0.20 M in NH4Cl, what will be the pH of the resulting solution? Assume no volume change due to the addition of the NaOH.

a) 4.80
b) 8.95
c) 5.05
d) 8.65
e) 9.20

10. A solution is initially 0.100 M in HOCl and 0.300 M in NaOCl. What is the pH if 0.030 mol of solid NaOH is added to 1.00 L of this solution? Assume no volume change.

a) 5.24
b) 5.38
c) 8.02
d) 8.13
e) 9.06

11. Which of the following aqueous solutions are good buffer systems?

I. 0.20 M calcium hydroxide + 0.20 M calcium chloride
II. 0.35 M ammonia + 0.32 M ammonium nitrate
III. 0.10 M hypochlorous acid + 0.14 M hydrobromic acid
IV. 0.33 M barium iodide + 0.27 M sodium iodide
V. 0.29 M hydrochloric acid + 0.19 M sodium chloride

a) II III, and IV
b) II and V
c) I and IV
d) II
e) All would be good buffers

12. What is the [H3O+] of a solution that is 0.0100 M in HOCl (Ka = 3.5 x 10-8) and 0.0300 M in NaOCl?

a) 2.14 x 10-7 M
b) 1.45 x 10-7 M
c) 7.41 x 10-8 M
d) 2.29 x 10-8 M
e) 1.17 x 10-8 M

13. What is the pH at the equivalence point in the titration of 50.0 mL of 0.100 M hydrofluoric acid, HF, (Ka = 7.2 x 10-4) with 0.100 M NaOH?

a) 5.88
b) 6.08
c) 7.92
d) 8.12
e) 8.56

14. How many grams of solid sodium acetate should be added to 1.50 L of a 0.287 M acetic acid solution to prepare a buffer with a pH of 4.140 ? Grams sodium acetate = ?

a) 2.43 g
b) 8.77 g
c) 4.14.g
d) 8.00 g

15. Which salt dissolved in water will give the highest pH?

a) NaCl
b) KBr
c) NaNO3
d) NH4Cl
e) NaF

16. The Ka of the weak acid HNO2 is 7.4 x 10-4. What is the Kb of its conjugate base, NO2 -?

a) 7.4 x 10-4
b) 1.35 x 103
c) 1.35 x 10-11
d) 1.0 x 10-14
e) 1.8 x 10-5

17. What is the pH of 0.10 M sodium acetate (NaAc) solution? The Ka of acetic acid (HAc) is 1.8 x 10-5.

a) 1.0
b) 0.10
c) 7.0
d) 8.9
e) 5.1

18. Which titration curve below represents the titration of a strong base with a strong acid titrant?

Consider the following table of indicator ranges.

19. Which indicator(s) would be the best choice for the titration like the (b) curve in Problem #18?

a) Methyl orange and methyl red would work best.
b) Bromothymol blue and phenolphthalein would work.
c) Methyl red would be best.
d) Phenolphthalein would work best.

KEY

1)a 2)d 3)e 4)c 5)d 6)a 7)c 8)d 9)e 10)d 11)d 12)e 13)c 14)b 15)e 16)c 17)d 18)a 19)d

Find the Ph of a 0.32 M Ethylamine C2h5nh2 Solution

Source: https://www.cae.tntech.edu/~snorthrup/chem1120/QUIZ3-16.html