Exam3
Determine the pH of a 0.023 M HNO3 solution
-log(0.023)=1.64
Adding 300 mL: ph=
12.4
Determine the pH of a 0.116 M Ba(OH)2 solution
13.37
A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH. Determine the pH of the solution before the addition of any KOH. The Ka of HF is 3.5 x 10-4.
2.08
Determine the molar solubility of Fe(OH)2 in pure water. Ksp for Fe(OH)2= 4.87 x 10^-17
2.30 x 10^-6 M Fe(OH)2 (s) <=> Fe2+ + 2 OH- let x = mol/L of Fe(OH)2 that dissolve : this will give x mol/L Fe2+ and 2 mol/L OH- Ksp = 4.87 x 10^-17 = [Fe2+][OH-]^2 = (x)(2x)^2 = 4 x^3 x = molar solubility =2.30 x 10^-6 M
A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH. Determine the pH of the solution after the addition of 100.0 mL of KOH. The Ka of HF is 3.5 x 10^-4
3.46 (.1L)(.20M)=.02 mol Hf (.1L)(.10)= 0.01 mol KOH subtract .01 from .02 since adding KOH, not HF pKa=-log(3.5 x10^-4)=3.46 pH= 3.46 + log(.01/.01)=3.46
Determine the molar solubility of AgBr in a solution containing 0.200 M NaBr. Ksp (AgBr) = 7.7 x 10^-13
3.8 x 10^-12 M 7.7E-13/ .200
Calculate the pH of a buffer that is 0.225 M HC2H3O2 and 0.162 M KC2H3O2. The Ka for HC2H3O2 is 1.8 x 10^-5
4.60 pH= -log(1.8 x 10^-5) + log (0.162/0.225)=4.60
Determine the pH of of a 0.62 M NH4Br solution
4.73
Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 M HClO with 100.0 mL of 0.20 M KClO. The Ka for HClO is 2.9 x 10^-8.
7.06 (.3 M)(.200L) = .06 moles HClO / .300 L = 0.20 M HClO (.2 M)(.100L)= .02 moles KClO/ .300 L = 0.067 M KClO pka=-log(2.9x10^-8) = 7.54 pH= 7.54 + log (.067/.20)= 7.06 or u could use log(.02/.06)
A 100.0 mL sample of 0.20 M HF is titrated with 0.10 M KOH. Determine the pH of the solution after the addition of 200.0 mL of KOH. The Ka of HF is 3.5 x 10^-4
8.14 moles KOH = 0.200 L x 0.10 M= 0.020 = moles HF moles F- = 0.020 total volume = 0.300 L [F-]= 0.020/ 0.300=0.067 M F- + H2=<=> HF + OH- Kb = Kw/Ka =2.9 x 10^-11 = x^2 / 0.067-x x = [OH-]= 1.4 x 10^-6 M pOH = 5.9 pH = 8.1
Determine the Ka of an acid whose 0.294 M solution has a pH of 2.80
8.5 x 10^-6 [H+] = 10^-2.8 = 0.00158 M [H+] = [A-] = 0.00158 M [HA] = 0.294 M Ka = (0.00158) (0.00158) / 0.294 = 8.55x10^-6
Calculate the pH of a solution that contains 7.8 x 10^-6 M OH- at 25 C.
8.89
Calculate the pH of a solution that has a molarity of 7.8E-6 OH-
8.89
Determine the pH of a 0.22 M NaF solution at 25 C. The Ka of HF is 3.5 x 10^-5.
8.90
Determine the pH of a 0.22 M NaF solution. The Ka of HF is 3.5x10^-5
8.90
Determine the pH of a 0.227 M C5H5N solution
9.29
Which is true
Acidic has H3O>OH-
Which of the following solutions would have the highest pH? Assume that they are all 0.10 M in acid at 25°C. The acid is followed by its Ka value. A) HF, 3.5 × 10-4 B) HCN, 4.9 × 10-10 C) HNO2, 4.6 × 10-4 D) HCHO2, 1.8 × 10-4 E) HClO2, 1.1 × 10-2
B
Which is polyprotic?
H2SO4
Which is not a conjugate acid-base pair?
H3O+/OH-
Increasing acid strength
HBrO<HBrO2<HBrO3<HBrO4
Which is a weak acid?
HCO2H
Which of the following acids is the strongest?
HClO2, 1.1x10^-2 larger Ka=stronger
All of the following anions are considered basic except
HPO42-
Amphoteric
HPO42-
What is the conjugate base of H2PO42-?
HPO42-
Which is a Bronsted-Lowry acid?
NH4+
Which is true?
The conjugate base of a very weak acid is stronger than the conjugate base of a strong acid
A Lewis acid
accepts electrons
FeCl3, Al(NO3)3, NH4Br
acidid
NaF, Ca(C2H3O2)2, KNO2
basic
A Lewis base
donates electrons
Higher Ksp=_____molar solubility in water
higher
NaCl, Ca(NO3)2, KBr
neutral
When titrating a strong monoprotic acid with KOH at 25 C, the
pH will be equal to 7 at the equivalence point
When titrating a monoprotic strong acid with a weak base at 25 C, the
pH will be less than 7 at eq pt
