# Assignment 8: 15.1 - 15.8

## Unlock all answers in this set

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Clâˆ’
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H2PO4âˆ’
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CHO2âˆ’
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Fâˆ’
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C2H5NH3+
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HClO4
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H2PO4âˆ’
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H2CO3
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Classify each of the following acids as strong or weak. HF
Weak
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HCHO2
weak
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H2SO4
strong
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H2CO3
weak
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Write an expression for the acid ionization constant (Ka) for HCHO2.
Ka=[H3O+][CHO2âˆ’]/[HCHO2]
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Write an expression for the acid ionization constant (Ka) for HF.
Ka=[H3O+][Fâˆ’]/[HF]
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Write an expression for the acid ionization constant (Ka) for H2CO3.
Ka=[H3O+][HCOâˆ’3]/[H2CO3]
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Consider the given acid ionization constants. Identify the strongest conjugate base. Acid Ka HNO2(aq) 4.6Ã—10âˆ’4 HCHO2(aq) 1.8Ã—10âˆ’4 HClO(aq) 2.9Ã—10âˆ’8 HCN(aq) 4.9Ã—10âˆ’10
CNâˆ’(aq)
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What is the pH of a solution whose hydroxide ion concentration, [OH-], is 4.3 Ã— 10-4 M?
10.63
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What is the H+ concentration for an aqueous solution with pOH = 3.58 at 25 âˆ˜C? Express your answer to two significant figures and include the appropriate units.
[H+] = 3.8Ã—10âˆ’11 M
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Arrange the following aqueous solutions, all at 25 âˆ˜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
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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 = 3.3Ã—10âˆ’15
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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
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A certain weak acid, HA, has a Ka value of 9.7Ã—10âˆ’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 %
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Calculate the percent dissociation of HA in a 0.010 M solution. Express your answer as a percent using two significant figures.
0.98%
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Find the pH of a 0.390 M aqueous benzoic acid solution. For benzoic acid, Ka=6.5â‹…10âˆ’5. Express your answer using two decimal places.
pH= 2.30
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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
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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 = 3.9Ã—10âˆ’4
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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 = 5.9Ã—10âˆ’4
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If Kb for NX3 is 3.0Ã—10âˆ’6, what is the pOH of a 0.175 M aqueous solution of NX3? Express your answer numericall
pOH= 3.14
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If Kb for NX3 is 3.0Ã—10âˆ’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 %
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If Kb for NX3 is 3.0Ã—10âˆ’6 , what is the the pKa for the following reaction? HNX3+(aq)+H2O(l)â‡ŒNX3(aq)+H3O+(aq) Express your answer numerically to two decimal places.
pKa= 8.48
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What is the relationship between the acid ionization constant for a weak acid (Ka) and the base ionization constant for its conjugate base (Kb )?
Kaâ‹…Kb=Kw
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Which of the following anions act as weak bases in solution? Check all that apply.
NO2âˆ’ C2H3O2âˆ’
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For NO2âˆ’, 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.
NO2âˆ’(aq)+H2O(l)â‡ŒHNO2(aq)+OHâˆ’(aq)
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For C2H3O2âˆ’, 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.
C2H3O2âˆ’(aq)+H2O(l)â‡ŒHC2H3O2(aq)+OHâˆ’(aq)
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Determine the [OHâˆ’] of a solution that is 0.140 M in Fâˆ’. Express your answer using two significant figures.
[OHâˆ’] = 2.0Ã—10âˆ’6 M
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Determine the pH of this solution. Express your answer to two decimal places.
pH= 8.30
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Determine whether each of the following cations is acidic or pH-neutral. Sr2+
pH- neutral
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Mn3+
acidic
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C5H5NH+
acidic
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Li+
pH-neutral
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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)â‡ŒMn(H2O)5OH2+(aq)+H3O+(aq)
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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)â‡ŒC5H5N(aq)+H3O+(aq)
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Which aqueous solution is expected to have a pH less than 7?
NH4Br (aq)
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Given that at 25.0 âˆ˜C Ka for HCN is 4.9Ã—10âˆ’10 and Kb for NH3 is 1.8Ã—10âˆ’5, calculate Kb for CNâˆ’ and Ka for NH4+. Enter the Kb value for CNâˆ’ followed by the Ka value for NH4+, separated by a comma, using two significant figures.