CHEM 1312 Exam 2

What is the pH of a buffer that consists of 0.378 M CH3CH2COONa and 0.473 M CH3CH2COOH?Ka of propanoic acid, CH3CH2COOH is 1.3 x 10-5

4.79 -log(1.3 x 10-5) + log(.378/.473)

What is the pOH of a 7.599 x 10-1 M solution of RbOH?

0.12 -log(7.599 x 10-1)

What is the buffer component ratio, (NO2-)/(HNO2) of a nitrite buffer that has a pH of 2.69. Ka of HNO2 is 7.1 x 10-4.

0.348 2.69= -log(7.1 x 10-4) + log(NO2-)/(HNO)

At 25 oC the solubility of calcium phosphate is 6.44 x 10-7 mol/L. Calculate the value of Ksp at this temperature. Give your answer in scientific notation to 2 sf

1.2E-29 Ca3(PO4)2- -> 3Ca2+ + 2PO43- [Ca2+] = 3(6.44 x 10-7) = 1.9E-6 [PO43-] = 2(6.44 x 10-7) = 1.3E-6 Ksp = [Ca2+]^3 * [PO43-]^2 = (1.9E-6)^3 * (1.3E-6)^2 Ksp = 1.2E-29

What is the pH of a solution prepared by diluting 25.00 mL of 0.124 M HCl with enough water to produce a total volume of 96.22 mL?

1.49 M1V1=M2V2 .124(.025) = M2 (.09622) M2 = .032 -log(.032)

Calculate the pH during the titration of 20.0 mL of 0.25 M HBr with 0.25 M KOH after 16.87 mL of the base have been added.

1.67 change to mol HBr + KOH = H2O + KBr .005 .0042 0 -.0042 -.0042 +.0042 .0008 0 .0042 H+ = mol HNO3/L = .0008/(.02+.01687) = .02 pH = -log(H+) pH = -log(.02) = 1.67

The Ksp of AgCl is 1.6 x 10-10. What is the solubility of AgCl in 0.010 M KCl? Give your answer using scientific notation and to 2 significant figures

1.6E-8 AgCl -> Ag+ + Cl- 1.6E-10 0 .01 +x +x 1.6E-10 x .01+x Ksp = [Ag+] [Cl-] 1.6E-10 = x(.01+x) take away +x x = 1.6E-8

What is the solubility in moles/liter for iron(II) hydroxide at 25 oC given a Ksp value of 1.6 x 10-14

1.6e-5 Fe(OH)2 -> Fe2+ + 2OH- 0 0 +x +2x 1.6 x 10-14 = x(2x)^2

At 25 oC the solubility of mercury(II) sulfide is 1.26 x 10-26 mol/L. Calculate the value of Ksp at this temperature. Give your answer in scientific notation to 2 SIGNIFICANT FIGURES

1.6e-52 HgS -> Hg2+ + S2- [Hg2+] = 1.26 x 10-26 [S2-] = 1.26 x 10-26 Ksp = [Hg2+] [S2-] = 1.26 x 10-26 * 1.26 x 10-26 Ksp = 1.6e-52

Calculate the pH during the titration of 20.00 mL of 0.1000 M C6H5OH(aq) with 0.2000 M NaOH(aq) after 7.02 mL of the base have been added. Ka of phenol = 1.0 x 10-10.

10.37 C6H5OH + NaOH = C6H5ONa + H2O .002 .0014 0 -.0014 -.0014 .0006 0 pH = -log( 1.0 x 10-10) + log(.0014/.0006) = 10.37

What is the solubility in moles/liter for copper(I) chloride at 25 oC given a Ksp value of 1 x 10-6. Write using scientific notation and use 1 or 2 decimal places

1.0e-3 CuCl -> Cu+ + Cl- Ksp = [Cu+][Cl-] 1 x 10-6 = x^2 x = 1E-3

The solubility of silver dichromate at a given temperature is 0.00395 g/100 mL. Calculate the Ksp at this temperature. After you calculate the Kspv alue, take the negative log and enter the (pKsp) value with 2 decimal places.

11.51 0.00395 g/100 mL = 9.14 x 10^-5 M Ag2Cr2O7 -> Cr2O72- + 2Ag+ [Cr2O72-] = 9.14 x 10^-5 M [Ag+] = 2(9.14 x 10^-5) = 1.8 x10^-4 Ksp = [Cr2O72-][Ag+]^2 = (9.14 x 10^-5)(1.8 x10^-4)^2 Ksp= 3.06E-12 -log(3.06E-12) = 11.51

Calculate the pH of a 0.20 M solution of methylamine (CH3NH2, Kb = 4.4 x 10-4.) 8.33 11.97 2.03 10.64 5.67

11.97 4.4 x 10-4 = x^2/.2 x = 9.4 x 10^-3 pOH = -log(9.4 x 10^-3) = 2.03 pH = 14 - 2.03 = 11.97

Calculate the pH during the titration of 30.00 mL of 0.1000 M NaOH(aq) with 0.1000 M HCl(aq) after 16.33 mL of the acid have been added.

12.47 same as before but 14 - 1.53

What is the pH of a 4.7 x 10-2 M solution of KOH?

12.7 -log(4.7 x 10-2) 14 - 1.3 = 12.7

Calculate the pH of a 0.400 M solution of lactic acid, for which the Ka value is 1.40 x 10-4. 11.87 2.13 5.27 8.73 7.48 x 10-3

2.13 Do ice table 1.40 x 10-4 = x^2/(.4-x) x = 7.5 x 10^-3 pH = -log(7.5 x 10^-3)

Calculate the pH of a 0.181 M solution of phenylacetic acid, for which the Ka value is 4.90 x 10-5.

2.53 4.90 x 10-5. = x^2/.181 x = 2.98 x 10^-3 pH = -log(2.98 x 10^-3) = 2.53

What is the pH of a 0.0015 M solution of HNO3? 11.18 5.65 2.82 You need the Ka value to answer this 0.0015

2.82 -log(.0015)

The Ksp of Al(OH)3 is 1.0 x 10-33. What is the solubility of Al(OH)3 in 0.0000010 M Al(NO3)3?

3.3e-10 Al(OH)3 -> Al3+ + 3OH- .000001 0 x 3x .000001+x 3x 1.0 x 10-33 = (.000001+x)(3x)^3 take +x away

At a certain temperature, a 0.333 M HOCl solution is measured to have a pH = 3.97.What is the value of Ka for hypochlorous acid, at this temperature?

3.45E-8 [H+] = x = 10^-3.97 = 1.07E-4 Ka = x^2/.333-x Ka = (1.07E-4)^2/(.333-1.07E-4) = 3.45E-8

Calculate the pH when 0.71 g of NaF is added to 24 mL of 0.50 M HF. Ignore any changes in volume. The Ka value for HF is 3.5 x 10-4.

3.60 mol NaF = .71/42 = .017 M NaF = .017/.024 = .7 pH = -log(3.5 x 10-4)+log(.7/.5) = 3.6

A solution of weak base has a pOH of 2.56. What is the hydrogen ion concentration, [H+], of this solution?

3.63E-12 pH= 14-2.56 = 11.44 [H+] = 10^-11.44 = 3.63E-12

A buffer that contains 0.47 M of an acid, HA and 0.32 M of its conjugate base A-, has a pH of 4.01. What is the pH after 0.011 mol of NaOH are added to 0.74 L of the solution?

4.02 Initial: A- = 0.32*.74 = .2368 mol HA = .47*.74 = .3478 mol 4.01 = pKa + log(.2368/.3478) pKa = 4.18 Final: A- = .2368+.011 = .2478 mol HA= .3478+.011 = .3588 mol pH = 4.18 + log(.2478/.3588) = 4.02

The Ksp of CaF2 is 4.0 x 10-11. What is the solubility of CaF2 in 0.0010 M NaF

4.0e-5 CaF2 -> Ca2+ + 2F- 4E-11 0 .001 +x +x 4E-11 x .001+x Ksp = [Ca2+] [F-]^2 4E-11 = x(.001+x)^2

Determine the pH at the equivalence (stoichiometric) point in the titration of 25.51 mL of 0.173 M hydrazine(aq) with 0.269 M HCl(aq). The Kb of hydrazine is 1.7 x 10-6.

4.6 same as above but stop at pOH

Calculate the pOH of a solution that results from mixing 35.1 mL of 0.13 M HCN(aq) with 24.7 mL of 0.15 M NaCN. The Ka value for HCN is 4.9 x 10-10.

4.78 35.1 * .13 = 4.56 24.7 * .15 = 3.71 pH = -log(4.9 x 10-10) +log(3.71/4.56) = 9.22 pOH = 14 - 9.22 = 4.78

Calculate the pH when 1.79 g of CH3COONa (FW = 82.03 g/mol) is added to 29.8 mL of 0.500 M acetic acid, CH3COOH. Ignore any changes in volume. The Ka value for CH3COOH is 1.8 x 10-5.

4.91 1.79/82.03 = .02mol/.0298L = .73 pH = -log(1.8 x 10-5) + log(.73 /.5) = 4.91

What is the pH of 0.303 M dimethylammonium iodide, (CH3)2NH2I? The Kb of (CH3)2NH is 5.9 x 10-4.

5.64 ka = (1x10^-14)/(5.9 x 10-4) = 1.7 x 10^-11 1.7 x 10^-11 = x^2/.303 x = 2.3 x 10^-6 pH = -log(2.3 x 10^-6) = 5.64

Determine the volume in mL of 0.158 M NaOH(aq) needed to reach the equivalence (stoichiometric) point in the titration of 32.71 mL of 0.261 M propanoic acid(aq). The Ka of propanoic acid is 1.3 x 10-5.

54.03 mol of acid = .0085 x L * .158 mol/L = .0085 mol x L = .0085/.157 = .054ml

The Ksp of AgCl is 1.6 x 10-10. What is the solubility of AgCl in 0.0010 M CaCl2? Give your answer using scientific notation and to 2 significant figures

8.0E-8 AgCl -> Ag+ + Cl- 1.6E-10 0 2(.001) +x +x 1.6E-10 x .002+x Ksp = [Ag+] [Cl-] 1.6E-10 = x(.002+x) take away +x x = 8E-8

Calculate the pH during the titration of 20.00 mL of 0.1000 M hydrazine, NH2NH2(aq), with 0.1000 M HCl(aq) after 10.64 mL of the acid have been added. Kb of hydrazine = 1.7 x 10-6.

8.17 NH2NH2 + HCl = NH2NH3+ + Cl- .002 .0011 -.0011 -.0011 .0009 Ka = (1x10^-14)/(1.7 x 10-6) = 5.9 x 10^-9 pH = -log(5.9 x 10^-9) + log(.0009/.0011) = 8.17

Calculate the pH of a 0.40 M solution of sodium formate (NaHCOO) given that the Ka of formic acid (HCOOH) is 1.8 x 10-4. 8.67 2.07 5.33 10.26 11.93

8.67 NaHCOO is basic Kb = (1x10^-14)/(1.8 x 10-4) kb = 5.6 x 10^-11 5.6 x 10^-11 = x^2/.4 x = 4.7 x 10^-6 pOH = -log(4.7 x 10^-6) = 5.3 pH = 14 - 5.3

Calculate the pH of a 0.30 M solution of sodium benzoate (NaC6H5COO) given that the Ka of benzoic acid (C6H5COOH) is 6.50 x 10-5. 8.83 2.35 5.17 11.65 9.81

8.83 NaC6H5COO is basic Kb = (1x10^-14)/(6.50 x 10-5) kb = 1.5 x 10^-10 1.5 x 10^-10 = x^2/.3 x = 6.8 x 10^-6 pOH = -log(4.7 x 10^-6) = 5. pH = 14 - 5.3

Determine the pH at the equivalence (stoichiometric) point in the titration of 25.37 mL of 0.292 M propanoic acid(aq) with 0.187 M NaOH(aq). The Ka of propanoic acid is 1.3 x 10-5.

8.97 M1V1= M2V2 -> V2= .04 L total vol = .04 + .02537 = .065 L Initial conc = .292*.02537 = 7.4x10^-3 mol/.065L = .11M Kb = (1x10^-14)/(1.3 x 10-5) = 7.7 x 10^-10 7.7 x 10^-10 = x^2/.11 x = 9.36 x10^-6 pOH = -log(9.36 x10^-6) = 5.03 pH = 14- 5.03 = 8.97

A buffer that contains 0.41 M of a base, B and 0.11 M of its conjugate acid BH+, has a pH of 9.29. What is the pH after 0.035 mol of HCl are added to 0.75 L of the solution?

9.18 same as before but 14 - 4.82

What is the pH of a one liter solution that is 0.100 M in NH3 and 0.100 M in NH4Cl after 1.33 g of NaOH has been added? Given: Kb for NH3 is 1.81 x10-5 at 25 °C.

9.5 mol NaOH =.03 NH4+ + OH- ---> NH3 + H20 .1 .1 -.03 +.03 0.07 0.13 pOH = -log 1.8 x 10-5 + log [ 0.07 / 0.13] pOH = 4.476 pH = 14 - 4.476= 9.524

Is an aqueous solution of FeCl3 acidic, basic or neutral

A

The solubility of magnesium phosphate is 3.32 x 10-4 g/L (MM = 262.9 g/mol) Calculate the Ksp for Mg3(PO4)2

A. 3.5 x 10-28 change g/L to mol/L

Calculate the pH of a solution prepared by adding 20.0 mL of 0.100 M HCl to 80.0 mL of a buffer that is comprised of 0.25 M NH3 and 0.25 M NH4Cl. Kb of NH3 = 1.8 x 10 -5. A. 9.17 B. 9.26 C. 4.66 D. 9.34 E.4.83

A. 9.17 Initial mol= .25*.08 = 0.02 mol for both Mol added = .02*.1 = .002 mol NH3 + H+ == NH4+ .02 .002 .02 -.002 -.002 +.002 0.018 0 .022 10^-14/kb = 5.6E-10 pOH = -log(5.6 x 10-10) + log(.018/0.022) = 9.17

A 0.060 M solution of an acid has a pH of 5.12. Calculate the Ka of the acid. A. 9.59 x 10-10 B. 5.75 x 10-11 C. 7.59 x 10-6 D. 4.55 x 10-7 E. 2.75 x 10-3

A. 9.59 x 10-10 [H+] = 10^-5.12 plug in the equation with .06

Which indicator would be the best to use for a titration between 0.20 M HI with 0.10 M Ba(OH)2? A. bromothymol blue, color change at pH 6-8 B. thymol blue, color change at pH 2-4 C. alizarin yellow R, color change at pH 10-12 D. phenolphthalein, color change at pH 8-10 E. methyl red, color change at pH 3-5

A. bromothymol blue, color change at pH 6-8 strong acid + strong base = neutral

Which of the following acids has the weakest conjugate base? A. chloroacetic acid, Ka = 1.26 x 10-3 B. benzoic acid, Ka = 6.31 x 10-5 C. 3-chlorobenzoic acid, pKa = 3.8 D. ascorbic acid, pKa = 4.1 E. 2-hydroxybenzoic acid, pKa = 3.0

A. chloroacetic acid, Ka = 1.26 x 10-3 Change to Ka and choose the largest one

Is an aqueous solution of KCN acidic, basic or neutral

B

Is an aqueous solution of KHCO3 acidic, basic or neutral

B

At a certain temperature, the percent dissociation (ionization) of chlorous acid, HClO2, in a 1.43 M solution water is 8.0%. Calculate the value of Ka for chlorous acid at this temperature. A. 1.1 x 10-1 B. 9.9 x 10-3 C. 4.7 x 10-3 D. 8.0 x 10-2 E. 1.3 x 10-2

B. 9.9 x 10-3 .08 = x/1.43 x = .115 Ka = x^2/1.43-x plug x in

If 100.0 mL of a 0.500 M aqueous hydrazine is mixed with 100.0 mL of 0.500 M aqueous hydrochloric acid, what will be the pH of the resulting solution? Hydrazine (NH2NH2) has a Kb = 3.0 x 10-6. A. =7 B. <7 C. >7 D. Cannot be predicted from the information given

B. <7 Initial mols: .1*.5 = 0.05 mol for both Total vol= .2L [H2NNH3+] = (0.0500 mol/0.2 L) = 0.250 M Ka = 10^-14/(3x10^-6) = 3.33x10-9 Ka = x^2/.25 x = 2.89x10-5 pH = -log[2.89x10-5] = 4.54

What are the formal charges on each of the atoms in the AsH4+ ion? A. As = 0; H = +1 B. As = +1; H = 0 C. As = 0; H = 0 D. As = +4; H = -1 E. As = 0; H = +(1/4)

B. As = +1; H = 0 draw lewis structure, FC = valence - nonbonding- bonding e/2 As: 5-0-8/2 H: 1-0-2/2

When 7.5 x 10-4 g of KOH is dissolved in 1.00 L of 1.0 x 10-10 M Cu(NO3)2, a precipitate of Cu(OH)2 is formed. True or False? (Ksp of Cu(OH)2 is 2.2 x 10-20) A. True B. False

B. False mol OH- = (7.5 x 10-4 g)/56g = 1.3x10-5mol mol Cu2+ = 1.0E-10 mol Cu(OH)2(s) ==> Cu2+(aq) + 2OH-(aq) Q = [Cu2+][OH-]^2 Q = (1.0E-10)(1.3x10-5)^2 Q = 1.69E-20 < Ksp

A precipitate of lead(II)chloride forms when 7.0 mg of NaCl is dissolved in 0.250 L of 0.12 M lead(II)nitrate. True or False? Ksp of PbCl2 is 1.7 x 10-5. A. True B. False

B. False mole Cl- = (.007g)/58.44g = 1.2x10-4mol mole Pb2+ = .12mol/L * .25 L = .03 mol PbCl2(s) ==> Pb2+(aq) + 2Cl-(aq) Q = [Pb2+][Cl-]^2 Q = (.03)(1.2x10-4)^2 Q = 4.32E-10 < Ksp

The Ksp of AgCl at 25 oC is 1.6 x 10-10. Consider a solution that is 1.0 x 10-5 M NaCl and 1.0 x 10-5 M AgNO3. A. Q > Ksp and a precipitate will not form. B. Q < Ksp and a precipitate will not form. C. Q < Ksp and a precipitate will form. D. The solution is saturated. E. Q > Ksp and a precipitate will form.

B. Q < Ksp and a precipitate will not form. Q = [Ag+][Cl-] Q = 1.0 x 10-5 x 1.0 x 10-5 Q = 1x10^-10

The formal charge on nitrogen in the nitrite ion, NO2-, is A. +2 B. +1 C. 0 D. -1 E. -2

C. 0

Calculate the pH of a solution prepared by adding 20.0 mL of 0.100 M HCl to 80.0 mL of a buffer that is comprised of 0.25 M CH3NH2 and 0.25 M CH3NH3Cl. Kb of CH3NH2 = 6.8 x 10-5. A. 9.83 B. 4.08 C. 9.75 D. 9.92 E. 4.25

C. 9.75 same as #68

Which of the following compounds will have a different solubility with a change in pH? A. AgI B. PbCl2 C. BaCrO4 D. CuBr E. Hg2I2

C. BaCrO4 I- conj base of strong acid Cl- conj base of strong acid Br- conj base strong acid only CrO42- conj base of weak acid so it will react with change in pH

The Ksp of Al(OH)3 at 25 oC is 1 x 10-33. Consider a solution that is 1.0 x 10-10 M in Al(NO3)3 and 1.0 x 10-8 M in NaOH. A. Q > Ksp and a precipitate will form. B. Q > Ksp and a precipitate will not form. C. Q < Ksp and a precipitate will not form. D. Q < Ksp and a precipitate will form. E. The solution is saturated.

C. Q < Ksp and a precipitate will not form. Q = [Al3+][OH-]^3 Q= 1x10^-34

Match each substance with the correct designation for the equation NH4+ + CN- <=> NH3 + HCN NH4+ CN- NH3 HCN A. conjugate base of HCN B. conjugate acid of CN- C. conjugate base of NH4+ D. conjugate acid of NH3

D NH4+ A CN- C NH3 B HCN

Which of the following compounds will not have a different solubility with a change in pH? A. AgF B. Ca3(PO4)2 C. SrCO3 D. CuBr E. CuS

D. CuBr it is soluble

For each of the pairs given, predict which acid is stronger i) H2S and H2Se ii) HBrO2 and HBrO3 iii) H2SeO3 and HBrO3 A. H2Se, HBrO2, H2SeO3 B. H2S, HBrO3, HBrO3 C. H2Se, HBrO3, H2SeO3 D. H2Se, HBrO3, HBrO3 E. H2S, HBrO3, H2SeO3

D. H2Se, HBrO3, HBrO3 stronger as move down, higher oxidation #

In which solution(s) will a precipitate form? I. 0.00090 g of Na2CrO4 (molar mass = 162.0 g/mol) is added to 225 mL of 0.00019 M AgNO3. Ksp Ag2CrO4 =1.1 x 10-12 II. 0.100L of 0.0015 M MgCl2 and 0.200L of 0.012 M NaF. Ksp MgF2 = 3.7 x 10-8 A. I no II yes B. I yes II no C. insufficient information given to say D. I no II no E. I yes II yes

D. I no II no 5.56E-6 mol/.225 = 2.5E-5 M CrO4 Ag2CrO4 -> 2Ag + CrO4 Ksp = (.00019)^2(2.5E-5) = .88E-13 < Ksp 0.0015 * .1/.3 = .0005 M Mg 0.012 * .2/.3 = .008 M F MgF2 -> 2F + Mg Ksp = (.008)^2 ( .0005) = 3.2E-8 <Ksp

For which salt in each of the following groups will the solubility depend on pH? i) AgF, AgCl ii) Sr(NO3)2, Sr(NO2)2 iii) Pb(OH)2, PbCl2 iv) Ni(NO3)2, Ni(CN)2 A. i) AgF; ii) Sr(NO2)2; iii) PbCl2; iv) Ni(CN)2 B. i) AgF; ii) Sr(NO3)2; iii) Pb(OH)2; iv) Ni(NO3)2 C. i) AgCl; ii) Sr(NO3)2; iii) PbCl2; iv) Ni(NO3)2 D. i) AgF; ii) Sr(NO2)2; iii) Pb(OH)2; iv) Ni(CN)2 E. i) AgCl; ii) Sr(NO2)2; iii) PbCl2; iv) Ni(CN)2

D. i) AgF; ii) Sr(NO2)2; iii) Pb(OH)2; iv) Ni(CN)2

Given the following pKa values, which is the strongest acid of those listed in the answers? HClO2 (pKa = 2.00) CCl3COOH (pKa = 0.52) HIO3(pKa = 0.77) HBrO2 (pKa = 4.69) HN3 (pKa = 4.72) A. HIO3 B. HBrO2 C. HClO2 D. HN3 E. CCl3COOH

E. CCl3COOH lower pka, stronger acid

Give the conjugate base of H3PO3

H2PO3-

Which of the following acids has the strongest conjugate base? HBrO, Ka= 2 x 10-9 HClO2, Ka= 1.2 x 10-2 HBrO2, Ka= 1.2 x 10-5 HClO, Ka= 3.5 x 10-8 HClO3, Ka= 1

HBrO, Ka= 2 x 10-9 lower Ka, stronger conj base

Which of the following is not a strong acid in aqueous solution? HI HF HBr HCl H2SO4

HF

Give the conjugate acid of PO33-

HPO32-

Give the conjugate acid of S 2-

HS-

Give the conjugate acid of SO42-. Write it ignoring super and subscripts

HSO4-

Select the weaker acid from each of the following pairs: I.HBr or H2Se II. HClO3 or H2SO3 III. H2SO3 or H2SO4 I. HBr, II. HClO3 III. H2SO4 I. HBr, II. H2SO3 III. H2SO4 I. H2Se, II. HClO3 III. H2SO3 I. H2Se, II. H2SO3 III. H2SO3 I. HBr, II. H2SO3 III. H2SO3

I. H2Se, II. H2SO3 III. H2SO3

Consider the reaction shown. Using your knowledge of relative acid-base strengths and equilibrium, determine what you can about the size of K c for the reaction. H3PO4(aq) + HSO4-(aq) ⇌ H2PO4-(aq) + H2SO4(aq) Kc < 1 Kc = 1 Kc > 1 Impossible to tell

Kc < 1

Use a table of Ka or Kb values to determine whether K c for the following reaction is less than, equal to or greater than 1 HCO3- + F- ⇌ CO32- + HF Kc = 1 Kc > 1 Kc < 1

Kc < 1 use table Ka x Kb x 1x10^-14

Use a table of Ka or Kb values to determine whether K c for the following reaction is less than, equal to or greater than 1 CH3CO2- + HSO4- ⇌ CH3CO2H + SO42- Kc = 1 Kc < 1 Kc > 1

Kc > 1

Determine the volume in mL of 0.544 M HNO3(aq) needed to reach the half-equivalence (stoichiometric) point in the titration of 45.75 mL of 0.624 M CH3NH2(aq)(aq). The Kb of methylamine is 3.6 x 10-4.

mol of base = .04575*.624 = .029 half of mol = .029/2 = .014 Vol = .014/.544 = 26.24 ml

Select the weaker acid from each of the following pairs: I. HI or HBr II. H3AsO3 or H2SeO3 III. HNO3 or HNO2 a) I. HBr II. H2SeO3 III. HNO2 b) I. HBr II. H3AsO3 III. HNO2 c) I. HBr II. H3AsO3 III. HNO3 d) I. HI II. H3AsO3 III. HNO2 e) I. HI II. H2SeO3 III. HNO3

b) I. HBr II. H3AsO3 III. HNO2

Phenol (C6H5OH) has a Ka = 1.05 x 10-10. If 100.0 mL of a 0.5000 M aqueous phenol solution is mixed with 100.0 mL of 0.5000 M aqueous sodium hydroxide, the resulting solution will have a pH

same as above but 14-pOH

Classify CH3COOH strong acid weak acid strong base weak base

weak acid

Classify H3AsO4 strong base weak base strong acid weak acid

weak acid

Classify CH3NH2 strong acid weak acid strong base weak base

weak base