SIUC CHEM 210 Chapter 14 homework

Select the pair of substances which is not a conjugate acid-base pair. 1) H3O+, H2O 2) H2S, S2- 3) HNO2, NO2- 4) NH3, NH2- 5) H2SO4, HSO4-

2

What is the pOH of a 0.0085 M KOH solution? 1) 2.07 2) 4.77 3) 9.23 4) 11.93 5) None of these choices is correct.

2.07

Which of the following pairs has the stronger acid listed first? 1) H2AsO3, H2AsO4 2) H2S, HCl 3) HI, HBr 4) H2SO3, H2SO4 5) HClO, HClO3

HI, HBr. This is because the A atom in H-A is larger when going down a period. In this case, Iodine is larger than Bromine. Therefore, the bond is weaker and it's a stronger acid

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak acid (0.10 mol L-1) with a strong base of the same concentration?

It is B because the pH starts higher and ends higher

The substance NaNO3 is considered 1) a weak Arrhenius acid. 2) a strong Arrhenius base. 3) a weak Arrhenius base. 4) a neutral compound. 5) a strong Arrhenius acid.

It is a neutral compound, because it has no hydroxide group or hydrogen atom.

The substance Ba(OH)2 is considered 1) a weak Arrhenius acid. 2) a strong Arrhenius base. 3) a weak Arrhenius base. 4) a neutral compound. 5) a strong Arrhenius acid.

It is a strong Arrhenius base, because there is no Nitrogen atom with a lone pair.

Which of the following is the strongest base? 1) CH3NH2 2) NaNO3 3) B(OH)3 4) Al(OH)3 5) LiOH

LiOH. You can rule out those with weak bases as well as B(OH)3 and Al(OH)3 because they are both too similar (the same period and same number of OH groups)

Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H3O+] for a 0.20 M solution of picric acid? 1) 0.022 M 2) 0.29 M 3) 0.052 M 4) None of these choices is correct. 5) 0.15 M

.15

Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 Mbutyric acid has a pH of 2.71. What is the Ka for the acid? 1) 0.36 2) 1.5 ´ 10-5 3) 2.4 ´ 10-2 4) None of these choices is correct. 5) 7.8 ´ 10-3

1.5e-5

Farmers who raise cotton once used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1= 2.5 ´ 10-4, K2= 5.6 ´ 10-8, and K3= 3 ´ 10-13. What is the pH of a 0.500 M solution of arsenic acid? 1) 0.85 2) 1.96 3) 3.90 4) 4.51 5) None of these choices is correct.

1.96

What is the [OH-] for a solution at 25°C that has pH = 4.29? 1) 1.4 ´ 10-2 M 2) 7.3 ´ 10-13 M 3) 5.l ´ 10-5 M 4) 9.71 M 5) 1.9 ´ 10-10 M

1.9e-10

What is the pH of a 0.050 M triethylamine, (C2H5)3N, solution? Kb for triethylamine is 5.3 ´ 10-4. 1) 11.69 2) 8.68 3) 5.32 4) 2.31 5) < 2.0

11.69

What is the pOH of a 0.0250 M HI solution? 1) 0.944 2) 13.056 3) 1.602 4) None of these choices is correct. 5) 12.398

14- pH= pOH. >12.4 is the pOH

Which one of the following pairs is not a conjugate acid-base pair? 1) H2O/OH- 2) H2O2/HO2- 3) OH-/O2- 4) H2PO4-/HPO42- 5) HCl/H+

3

What is the [OH-] for a solution at 25°C that has [H3O+] = 2.35 ´ 10-3 M? 1) 4.26 ´ 10-5 M 2) 2.35 ´ 10-17 M 3) 2.35 ´ 10-11 M 4) None of these choices is correct. 5) 4.26 ´ 10-12 M

4.26e-12

Formic acid, which is a component of insect venom, has a Ka = 1.8 ´ 10-4. What is the [H3O+] in a solution that is initially 0.10 M formic acid, HCOOH? 1) 4.2 ´ 10-3 M 2) 1.8 ´ 10-5 M 3) 8.4 ´ 10-3 M 4) 1.8 ´ 10-6 M 5) 1.8 ´ 10-4 M

4.2e-3

The substance HCl is considered 1) a weak Arrhenius acid. 2) a strong Arrhenius base. 3) a weak Arrhenius base. 4) a neutral compound. 5) a strong Arrhenius acid.

A strong Arrhenius Acid This is because there are more Hydrogen atoms than oxygen atoms and it will completely dissociate.

The substance HClO4 is considered 1) a weak acid. 2) a strong base. 3) a weak base. 4) a neutral compound. 5) a strong acid.

A strong acid because it has 2 or more oxygen atoms than hydrogen atoms.

The substance H2SO3 is considered 1) a weak Arrhenius base. 2) a neutral compound. 3) a strong Arrhenius acid. 4) a weak Arrhenius acid. 5) a strong Arrhenius base.

A weak Arrhenius Acid This is because there are more Oxygen atoms than hydrogen atoms.

The substance NH3 is considered 1) a weak acid. 2) a strong base. 3) a weak base. 4) a neutral compound. 5) a strong acid.

A weak base, because it has a Nitrogen with a lone pair

Which one of the following will give a solution with a pH > 7, but is not an Arrhenius base in the strict sense? 1) CH3NH2 2) NaOH 3) CO2 4) Ca(OH)2 5) CH4

CH3NH2 because it doesn't contain an OH- group

Which of the following liquids contains the strongest acid?0.1 M HA, pH = 6.85 0.1 M HD, pH = 7.22 0.1 M HE, pH = 8.34 0.1 M HJ, pH = 11.88 pure water 1) HE 2) HA 3) HJ 4) HD 5) pure water

HA because it has the lowest pH

What is the pH of a 0.20 M HCl solution? 1) < 0 2) 0.70 3) 1.61 4) 12.39 5) 13.30

Molarity is calculated by the H+ concentration. Therefore, you can take the negative log of molarity. After doing this, you can find that the pH is .698 or .70.

What is the pH of a 0.050 M LiOH solution? 1) < 1.0 2) 1.30 3) 3.00 4) 11.00 5) 12.70

The negative log of the molarity (which represents the OH- concentration) will give the pOH. Subtract this from 14. The pH is 12.70

What is the pH of a 0.050 M HBr solution? 1) 0.89 2) 1.12 3) 1.30 4) 3.00 5) None of these choices is correct.

The pH is 1.30

Which of the following acids has the lowest pH? 0.1 M HBO, pKa = 2.43 0.1 M HA, pKa = 4.55 0.1 M HMO, pKa = 8.23 0.1 M HST, pKa = 11.89 pure water 1) HA 2) HST 3) HMO 4) HBO 5) pure water

To fin pH you need to find Ka and H3O+ Ka=10^-pKa. ->Ka=[H3O+]/Molarity ->pH=-log[H3O+]. ->After using this on all the answers, you can determine HBO is the answer.