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Assignment 8: 15.1 - 15.8

Terms in this set (47)

HCl
Express your answer as a chemical formula.
Cl−
H3PO4
Express your answer as a chemical formula.
H2PO4−
HCHO2
Express your answer as a chemical formula.
CHO2−
HF
Express your answer as a chemical formula.
F−
C2H5NH2
Express your answer as a chemical formula.
C2H5NH3+
ClO4−
Express your answer as a chemical formula.
HClO4
HPO42−
Express your answer as a chemical formula.
H2PO4−
HCO3−
Express your answer as a chemical formula.
H2CO3
Classify each of the following acids as strong or weak.
HF
Weak
HCHO2
weak
H2SO4
strong
H2CO3
weak
Write an expression for the acid ionization constant (Ka) for HCHO2.
Ka=[H3O+][CHO2−]/[HCHO2]
Write an expression for the acid ionization constant (Ka) for HF.
Ka=[H3O+][F−]/[HF]
Write an expression for the acid ionization constant (Ka) for H2CO3.
Ka=[H3O+][HCO−3]/[H2CO3]
Consider the given acid ionization constants. Identify the strongest conjugate base.
Acid Ka
HNO2(aq) 4.6×10−4
HCHO2(aq) 1.8×10−4
HClO(aq) 2.9×10−8
HCN(aq) 4.9×10−10
CN−(aq)
What is the pH of a solution whose hydroxide ion concentration, [OH-], is 4.3 × 10-4 M?
10.63
What is the H+ concentration for an aqueous solution with pOH = 3.58 at 25 ∘C?
Express your answer to two significant figures and include the appropriate units.
[H+] =
3.8×10−11 M
Arrange the following aqueous solutions, all at 25 ∘C, in order of decreasing acidity.
Rank from most acidic to most basic. To rank items as equivalent, overlap them.
Most acidic to least:
0.0023M HCl
pH= 5.45 & pOH= 8.55
0.0018 M KOH
At a certain temperature, the pH of a neutral solution is 7.24. What is the value of Kw at that temperature?
Express your answer numerically using two significant figures.
Kw =
3.3×10−15
What volume of a concentrated HCl solution, which is 36.0% HCl by mass and has a density of 1.179 g/mL, should be used to make 5.30 L of an HCl solution with a pH of 1.8?
Express your answer with the appropriate units.
V = 7.22 mL
A certain weak acid, HA, has a Ka value of 9.7×10−7.
Calculate the percent dissociation of HA in a 0.10 M solution.
Express your answer as a percent using two significant figures.
0.31 %
Calculate the percent dissociation of HA in a 0.010 M solution.
Express your answer as a percent using two significant figures.
0.98%
Find the pH of a 0.390 M aqueous benzoic acid solution. For benzoic acid, Ka=6.5⋅10−5.
Express your answer using two decimal places.
pH= 2.30
Determine the pH of a solution that is 3.55% KOH by mass. Assume that the solution has density of 1.01 g/mL.
Express your answer using two decimal places.
pH= 13.81
Aspirin (acetylsalicylic acid, C9H8O4) is a weak monoprotic acid. To determine its acid-dissociation constant, a student dissolved 2.00 g of aspirin in 0.600 L of water and measured the pH. What was the Ka value calculated by the student if the pH of the solution was 2.60?
Express your answer numerically using two significant figures.
Ka = 3.9×10−4
A 0.100 M solution of ethylamine (C2H5NH2) has a pH of 11.87. Calculate the Kb for ethylamine.
Express your answer numerically using two significant figures.
Kb = 5.9×10−4
If Kb for NX3 is 3.0×10−6, what is the pOH of a 0.175 M aqueous solution of NX3?
Express your answer numericall
pOH= 3.14
If Kb for NX3 is 3.0×10−6, what is the percent ionization of a 0.325 M aqueous solution of NX3?
Express your answer numerically to three significant figures.
percent ionization =
0.304 %
If Kb for NX3 is 3.0×10−6 , what is the the pKa for the following reaction?
HNX3+(aq)+H2O(l)⇌NX3(aq)+H3O+(aq)
Express your answer numerically to two decimal places.
pKa= 8.48
What is the relationship between the acid ionization constant for a weak acid (Ka) and the base ionization constant for its conjugate base (Kb )?
Ka⋅Kb=Kw
Which of the following anions act as weak bases in solution?
Check all that apply.
NO2−
C2H3O2−
For NO2−, write an equation that shows how the anion acts as a base.
Express your answer as a chemical equation. Identify all of the phases in your answer.
NO2−(aq)+H2O(l)⇌HNO2(aq)+OH−(aq)
For C2H3O2−, write an equation that shows how the anion acts as a base.
Express your answer as a chemical equation. Identify all of the phases in your answer.
C2H3O2−(aq)+H2O(l)⇌HC2H3O2(aq)+OH−(aq)
Determine the [OH−] of a solution that is 0.140 M in F−.
Express your answer using two significant figures.
[OH−] = 2.0×10−6 M
Determine the pH of this solution.
Express your answer to two decimal places.
pH= 8.30
Determine whether each of the following cations is acidic or pH-neutral.
Sr2+
pH- neutral
Mn3+
acidic
C5H5NH+
acidic
Li+
pH-neutral
For Mn3+, write an equation that shows how the cation acts as an acid.
Express your answer as a chemical equation. Identify all of the phases in your answer.
Mn(H2O)63+(aq)+H2O(l)⇌Mn(H2O)5OH2+(aq)+H3O+(aq)
For C5H5NH+, write an equation that shows how the cation acts as an acid.
Express your answer as a chemical equation. Identify all of the phases in your answer.
C5H5NH+(aq)+H2O(l)⇌C5H5N(aq)+H3O+(aq)
Which aqueous solution is expected to have a pH less than 7?
NH4Br (aq)
Given that at 25.0 ∘C
Ka for HCN is 4.9×10−10 and
Kb for NH3 is 1.8×10−5,
calculate
Kb for CN− and
Ka for NH4+.
Enter the Kb value for CN− followed by the Ka value for NH4+, separated by a comma, using two significant figures.
2.0×10−5,5.6×10−10
Keep these values in mind for the remaining questions:
Kb for CN− is 2.0×10−5.
Ka for NH4+ is 5.6×10−10.
Identify the following salts as neutral, acidic, or basic.
Neutral Salts: SrBr2, LiNO3
Acidic Salts: NH4Br, NH4ClO4
Basic Salts: NH4CN, LiF, KCN
Calculate the pH of a 0.20 M solution of KCN at 25.0 ∘C.
Express the pH numerically using two decimal places.
pH= 11.30
Calculate the pH of a 0.20 M solution of NH4Br at 25.0 ∘C.
Express the pH numerically using two decimal places.
pH= 4.98
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