CH.29 Acids & Bases -CH. 39 Entropy Flashcards
(28 cards)
Which of the following is a strong acid?
A. HF
B. HNO₃
C. H₂CO₃
D. CH₃COOH
Answer: B
✔️ HNO₃ (nitric acid) is one of the six strong acids.(HCIO4,
HClO4 > HI > HBr > HCl > H2SO4 > HNO3 > HClO3
Which base is weak?
A. NaOH
B. Ca(OH)₂
C. NH₃
D. KOH
Answer: C
✔️ NH₃ (ammonia) is a weak base, unlike group 1/2 metal hydroxides.
What is the pH of a 0.001 M HCl solution?
A. 1
B. 2
C. 3
D. 4
Answer: C
✔️ HCl is strong → [H⁺] = 0.001 M → pH = –log(1×10⁻³) = 3
If the pOH of a solution is 5, what is the pH?
A. 5
B. 7
C. 9
D. 14
Answer: C
✔️ pH + pOH = 14 → pH = 14 – 5 = 9
What is the conjugate base of HCO₃⁻?
A. CO₃²⁻
B. H₂CO₃
C. OH⁻
D. H₃O⁺
Answer: A
✔️ Conjugate base = remove H⁺ → HCO₃⁻ → CO₃²⁻
Which of the following is the conjugate acid of NH₃?
A. NH₂⁻
B. NH₄⁺
C. NH₃⁺
D. NO₃⁻
Answer: B
✔️ Conjugate acid = add H⁺ → NH₃ → NH₄⁺
What is the product of a reaction between HCl and NaOH?
A. H₂O and NaCl
B. H₂ and NaCl
C. NaClO and H₂
D. HClO and NaOH
Answer: A
when water is a
✔️ Strong acid + strong base → salt + water
Acid is always added to water true or false
true never add water to an acid as the acid can become too exothermic.
Which of the following best describes a buffer?
A. Strong acid + strong base
B. Weak acid + conjugate base
C. Weak base + strong acid
D. Neutral salt solution
Answer: B
✔️ Buffers = weak acid/base + conjugate base /acid pair
Which of the following statements is true about Ka and acid strength?
A. A lower Ka means a stronger acid
B. A higher Ka means a weaker acid
C. A higher Ka means a stronger acid
D. Ka is unrelated to acid strength
Answer: C
✔️ Stronger acids ionize more → higher Ka
If an acid has a Ka = 1.0 × 10⁻⁵, what is its pKa?
A. 1
B. 3
C. 5
D. 10
Answer: C
✔️ pKa = –log(Ka) = –log(10⁻⁵) = 5
Which of the following acids is the strongest based on pKa values?
A. pKa = 3
B. pKa = 5
C. pKa = 7
D. pKa = 10
Answer: A
✔️ Lower pKa = stronger acid
What happens to a buffer when small amounts of strong acid are added?
A. pH changes drastically
B. The buffer is destroyed
C. The pH changes slightly
D. The buffer becomes neutral
Answer: C
✔️ Buffers resist pH change — slight change only.
A buffer is made using 0.10 M acetic acid (pKa = 4.76) and 0.20 M acetate. What is the pH?
A. 4.46
B. 4.76
C. 5.06
D. 5.76
Answer: C
✔️ pH = 4.76 + log(0.20 / 0.10) = 4.76 + log(2) ≈ 4.76 + 0.30 = 5.06
The Bronsted – Lowry definition defines an acid as __________________.
a proton donor
a proton acceptor
an electron donor
an electron acceptor
None of the above
a proton donor AND the base is a proton acceptor
Which of the following substances is the conjugate acid of NH3?
NH4+
NH
NH2-
NH3
None of the above
NH4+
Which of the followings is an example of a Lewis acid?
BF3
CO2
AlCl3
NH4+
All of the above
All of the above
has a positive or neutral charge
if was Lewis base it would be negative or neutral
Which of the followings is an example of a Bronsted – Lowry base?
NH2-
OH-
Cl-
NH3
All of the above
All of the above it can be negative, positive, or neutral
Which of the following compounds is amphiprotic?
CO2
NH3
H2O
B and C
All of the above
B and C
An amphiprotic compound is any compound that can either accept or donate a proton !! can
co2 has no hydrogen
Which of the following compounds has the lowest pH?
HI
HBr
HClO4
H2SO4
HNO3
HClO4
The compound with the lowest pH is the strongest acid. Among the seven strong acids, HClO4 is the strongest and thus, has the lowest pH.
The order of strong acids from strongest to weakest:
HClO4 > HI > HBr > HCl > H2SO4 > HNO3 > HClO3
Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴
- What is the concentration of OH⁻ in a solution where [H⁺] = 1.0 × 10⁻³ M?
A. 1.0 × 10⁻³ M
B. 1.0 × 10⁻¹¹ M
C. 3.0 × 10⁻⁷ M
D. 1.0 × 10⁻¹⁴ M
Answer: B
Kw = [H⁺][OH⁻] = 1.0 × 10⁻¹⁴
1.0 × 10⁻¹⁴ / 1.0 x 10^-3 = 1.0 x10^-11
- In pure water at 25°C, what is the concentration of both H⁺ and OH⁻?
A. 1.0 × 10⁻⁷ M
B. 1.0 × 10⁻⁴ M
C. 1.0 M
D. 7.0 M
Answer: A
✔️ Water auto-ionizes:
it is just 1.0 × 10⁻¹⁴ the constant divided by 2 because Kw = [H⁺][OH⁻] is 2
What is the pH of a solution with [H⁺] = 1.0 × 10⁻⁶ M?
A. 4
B. 5
C. 6
D. 7
Answer: C
✔️ pH = –log(1.0 × 10⁻⁶) = 6
same for POH
If a solution has [H⁺] = 2.0 × 10⁻⁵ M, what is its pH approximately?
A. 4.3
B. 5.7
C. 5.0
D. 4.0
Answer: A
✔️ Estimate: –log(2 × 10⁻⁵) ≈ 5 – 0.3 = 4.7
