chem chapter 8 part 7

d-4.62

A buffer solution contains acetic acid (HC2H3O2) at a concentration of 0.225 M and sodium acetate (NaC2H3O2) at a concentration of 0.164 M. The value of Ka for acetic acid is 1.75 10−5. What is the pH of this buffer solution? A) 0.137 B) 0.862 C) 2.40 D) 4.62 E) 4.76 D

c 6.35

A buffer solution contains carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3), each at a concentration of 0.100 M. The relevant equilibrium is shown below. What is the pH of this buffer solution? H2CO3(aq) + H2O(l) H3O+(aq) + HCO3−(aq) Ka = 4.5 10−7 A) 4.50 B) 7.00 C) 6.35 D) 7.65 E) 2.16

Ans: True Bronsted Lowry- Acids: donates proton Bases: accept proton resolves issue for Arrhenius NH3+

All Brønsted-Lowry acids contain at least one hydrogen atom.

Ans: False

All Brønsted-Lowry bases contain hydroxide.

Ans: False 7 is neutral

All buffer solutions operate at a pH at or near 7.

Ans: True all metal hydroxides are strong bases

All metal hydroxides are strong bases.

CH3CH2CH2COOH(aq) + H2O(l) <---> CH3CH2CH2COO-(aq) + H3O+(aq)

Butyric acid is a weak acid. Which reaction equation properly represents the dissociation of butyric acid in water?

Ans: True The addition of an acid to water increases the [H3O+] hydronium and decreases the pH. ACid to water= H+ goes up PH goes down

The addition of an acid to water increases the [H3O+] and decreases the pH.

False Because A BUFFER solution resists large changes in PH when acids bases are added Buffer capacity resists large changes in PH when STRONG acids or bases are added

The combination of a weak acid and a strong acid form a buffer solution.

b

What is the conjugate base of H2SO4? A) SO42- B) HSO4− C) H2SO3 D) SO4− E) H2PO4+

oxidation

What is the general term for the process in which a chemical species loses electrons? A) oxidation D) Lewis base B) reduction E) decomposition C) dioxidation

1 x 10 -6

What is the hydronium ion concentration of a solution with a pH of 6.0?

d- 1.0

What is the hydronium ion concentration of pure water at 25°C? A) 7.0 107 M B) 7.0 10−7 M C) 1.0 107 M D) 1.0 10−7 M E) 1.0 10−14 M

B) 1.46

What is the pH of a 0.035 M HCl solution? A) 3.50 B) 1.46 C) 2.27 D) 5.59 E) 12.54

10

What is the pH of a 1.0 x 10−4 M solution of KOH? A) 4.00 B) 6.00 C) 7.00 D) 10.00 E) 14.00

b 2.22

What is the pH of a solution that has [H3O+] = 6.0 10−3 M? A) 1.7 10−12 B) 2.22 C) 3.60 D) 5.12 E) 11.78

b electron

What particle is transferred from one reactant to another in oxidation-reduction reactions? A) proton B) electron C) hydronium ion D) hydrogen ion E) hydride ion

Potential of Hydrogen

pH

BUffers consist of

weak acid & salt weak base & salt

Acetic ACid CH3COOH Carbonic Acid H2C03

weak acids CA

NH3+

weak base

A hydronium ion is a protonated water molecule. Ans: True

A hydronium ion is a protonated water molecule.

Ans: False A PH of 7 is neutral

A pH of 0 is considered neutral.

a- Increase the concentration of the weak acid.

A particular buffer solution consists of a weak acid and its conjugate base. How could this buffer solution be modified so as to increase its buffer capacity against added base? A) Increase the concentration of the weak acid. B) Increase the concentration of its conjugate base. C) Use a strong base and its conjugate acid instead. D) Use a strong acid and its conjugate base instead. E) Make the concentrations of the weak acid and its conjugate base equal.

a- acidic solution

A sample of black coffee was measured to have [H3O+] = 7.94 × 10−6. What is true about this solution? A) The solution is acidic. B) The solution contains less hydronium ions than pure water itself. C) The solution does not contain any OH− ions. D) The solution has [OH−] = 7.94 × 10−6. E) The pH of the solution is 7.94.

c-8.64

A solution containing a buffer has an initial pH of 8.78. If a student adds 5 drops of HCl to this solution, what would be a reasonable pH for the resulting solution? A) 5.22 B) 7.00 C) 8.64 D) 8.78 E) 8.89

True A standard solution is a solution whose concentration is accurately known.

A standard solution is a solution whose concentration is accurately known.

Ans: True Arhhenius Theory in water Acids: H+ Base: OH-

According to Arrhenius' theory of acids and bases, acids increase the hydrogen ion concentration in water. True/False?

d-1.0 m hcl

An aqueous solution with a low pH is necessary for a certain industrial process. Which of the following solutions would have the lowest pH? A) 2.0 M NaOH B) 0.5 M HCl C) 1.0 M acetic acid D) 1.0 M HCl E) All solutions would have the same pH.

Ans: True Strong acids are completely dissociated when dissolved in water.

Strong acids are completely dissociated when dissolved in water.

pH=-log[Ho3+]

To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). Negative log of the hydrogen ion concentration

B) A formic acid solution predominantly contains undissociated HCO2H molecules.

Formic acid (HCO2H) is a weak acid found in the venom of bees and ant stings. Which of the following is an accurate statement concerning an aqueous solution of formic acid? HCO2H(aq) + H2O(l) H3O+(aq) + HCO2−(aq) Ka = 1.8 10−4 A) The reaction between formic acid and water is slow, due to the low value for Ka. B) A formic acid solution predominantly contains undissociated HCO2H molecules. C) A formic acid solution predominantly contains H3O+ and HCO2− ions. D) A formic acid solution contains a greater concentration of dissolved ions than it does neutral formic acid molecules. E) A formic acid solution contains equal amounts of H3O+ and HCO2H.

hydronium ion

H30+

a The pH of the solution is 1.5.

HCl is a strong electrolyte. A bottle of HCl contains the label 0.015 M HCl(aq). Which statement concerning this HCl solution is FALSE? A) The solution is acidic. B) The pH of the solution is 1.5. C) The hydronium ion concentration in this solution is 0.015 M. D) The solution has a higher concentration of hydronium ions than hydroxide ions. E) The solution contains dissolved H3O+ and Cl− ions only; no HCl molecules are present.

Ans: True Strong Acids (degree of dissociation) HCl Sulfaric Acid Perchloric Acid Nitric Acid

Nitric acid is a strong acid and dissociates completely when dissolved in water. Hint Strong acids: (Hy Strong Nitric P)

NaOh KOH Ba(Oh)2

Strong Bases (all metal hydroxides) hint: BanK

Ans: False its the dissociation determines weak/strong base not concentration

The concentration of a weak acid or base affects its degree of dissociation in water.

Ans: True The ion product of water IS affected by change in temperature

The ion-product of water is affected by a change in temperature.

Ans: False Its bicarbonate buffer system Bicarbonate buffer system. Carbon dioxide, a by-product of cellular respiration, is dissolved in the blood, where it is taken up by red blood cells and converted to carbonic acid by carbonic anhydrase.

The main buffer system found in blood is the HCl/Cl− system.

water b

The reaction of an acid with a base produces a salt and another product. What is the identity of the other product? A) hydronium ion B) water C) a buffer D) a proton E) hydroxide ion

c-h20

The species that remains after an acid donates a proton is called its conjugate base. What is the conjugate base of the hydronium ion, H3O+? A) OH− B) H2O− C) H2O D) H2O+ E) H3O+ has no conjugate base.

c-0.0592 m

Titration of 25.0 mL of an HCl solution of unknown concentration requires14.8 mL of 0.100 M NaOH. What is the molar concentration of the HCl solution? NaOH(aq) + HCl(aq) ---> NaCl(aq) + H2O(l) A) 0.592 M B) 5.87 M C) 0.0592 M D) 0.0692 M E) 1.25 M

D) The solution resists large changes in pH when small amounts of acids or bases are added

What is always a characteristic of a solution that contains a buffer? A) The solution is neutral and has a pH of 7. B) The solution contains a small amount of solute dissolved in a large volume of solvent. C) The solution has been diluted by the addition of solvent. D) The solution resists large changes in pH when small amounts of acids or bases are added. E) The solution maintains a constant pH value; no amount of added acid or base can change the pH.

b-nh3

What is the conjugate acid of NH2-? A) NH2− B) NH3 C) NH4+ D) NH2+ E) NH4−

b It has a hydronium ion concentration that is higher than pure water itself.

What is true about a solution whose pH is less than 7? A) It has a hydronium ion concentration less than 1 × 10−7. B) It has a hydronium ion concentration that is higher than pure water itself. C) It has a hydroxide ion concentration equal to its hydronium ion concentration. D) It is a solution that requires a buffer. E) It is a basic solution.

a oxidizing agent

What term describes a reactant that removes electrons from another reactant? A) oxidizing agent B) reducing agent C) buffer D) base E) anode

E) Addition of a base to water increases the hydronium ion concentration of the solution. False

Which of the following statements concerning acids and bases is FALSE? A) A Brønsted-Lowry acid is a proton (H+) donor. B) A Brønsted-Lowry base is a proton (H+) acceptor. C) Reactions between acids and bases involve the transfer of a proton (H+) from the acid to the base. D) Addition of an acid to water decreases the pH of the solution. E) Addition of a base to water increases the hydronium ion concentration of the solution.

base does not increase H+ in water (yes OH-)

Which one of the following is NOT a characteristic property of a base? A) tastes bitter D) is corrosive B) feels slippery E) causes many metal ions to precipitate C) increases [H+] in water

D) Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases. false

Which statement concerning the relative strength of acids is FALSE? A) Strong and weak acids differ in their extent of proton transfer to water. B) Strong acids are good proton donors; weak acids are poor proton donors. C) A strong acid completely transfers its protons to water; a weak acid only partially transfers its protons to water. D) Strong acids produce strong conjugate bases; weak acids produce weak conjugate bases. E) A strong acid produces more hydronium ions in water than a weak acid of the same concentration.

A) A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton.

Which statement correctly describes conjugate acids and bases according to the Brønsted-Lowry theory? A) A conjugate base is the species formed when an acid donates a proton; a conjugate acid is the species formed when a base accepts a proton. B) A conjugate base is the species formed when an acid accepts a proton; a conjugate acid is the species formed when a base donates a proton. C) A conjugate acid is the species formed when an acid donates a proton; a conjugate base is the species formed when a base accepts a proton. D) A conjugate acid is an acid that does not completely transfer a proton to water; a conjugate base is a base that does not completely accept a proton from water. E) A conjugate acid is the solution formed when an acid is added to water; a conjugate base is the solution formed when a base is added to water