Acids and Bases
This is the ion an acid produces when dissolved in water
H+ or H3O+
A solution has [OH⁻] = 1×10⁻⁸ M. Calculate the pOH.
pOH = 8
This law states that pressure and volume are inversely proportional at constant temperature.
Boyle's Law (P₁V₁ = P₂V₂)
State the Ideal Gas Law equation and identify what each variable represents.
PV = nRT; P = pressure (atm), V = volume (L), n = moles, R = 0.0821, T = temperature (K)
The volume occupied by 1 mole of any ideal gas at STP.
22.4 L
KOH is a base because when dissolved in water, it releases this ion.
OH-
A solution has a pOH of 2. What is the pH, and is the solution acidic, basic, or neutral?
pH = 12; basic
A gas occupies 6.0 L at 1.0 atm. Pressure doubles to 2.0 atm at constant temperature. Find the new volume.
3.0 L
Find the volume of 1.0 mol of gas at 273 K and 1.0 atm. (R = 0.0821)
V = (1.0 × 0.0821 × 273) / 1.0 ≈ 22.4 L
How many moles are in 67.2 L of a gas at STP?
67.2 ÷ 22.4 = 3.0 moles
A solution of sulfuric acid (H₂SO₄) is added to water. Write the dissociation equation and explain what makes it an acid.
H₂SO₄ → 2H⁺ + SO₄²⁻; it is an acid because it produces H⁺ ions when dissolved in water.
A solution has [H⁺] = 1×10⁻⁵ M. Calculate the pH and pOH.
pH = 5; pOH = 9
A gas at 200 K occupies 5.0 L. Temperature rises to 400 K at constant pressure. Find the new volume and name the law.
10.0 L; Charles's Law (V₁/T₁ = V₂/T₂)
Find the volume of 1.5 mol of gas at 300 K and 2.0 atm. (R = 0.0821)
V = (1.5 × 0.0821 × 300) / 2.0 ≈ 18.5 L
What volume does 4.0 moles of gas occupy at STP?
4.0 × 22.4 = 89.6 L
A student is titrating an unknown base with HCl using phenolphthalein as an indicator. What color is the solution at the start, and what color change signals the equivalence point?
Starts dark purple (basic); turns light pink when the equivalence point is reached (solution becomes neutral)
Two solutions — one with pH 4 and one with pH 10. Which is acidic, which is basic, and what is the pOH of each?
pH 4 is acidic (pOH = 10); pH 10 is basic (pOH = 4)
A gas is at 1.0 atm and 200 K. Temperature increases to 400 K at constant volume. Find the new pressure and name the law.
2.0 atm; Gay-Lussac's Law (P₁/T₁ = P₂/T₂)
A 5.0 L container holds gas at 2.0 atm and 350 K. How many moles of gas are present? (R = 0.0821)
n = (2.0 × 5.0) / (0.0821 × 350) ≈ 0.35 mol
For N₂(g) + 3H₂(g) → 2NH₃(g): if 44.8 L of H₂ reacts at STP, how many liters of NH₃ are produced?
29.9 L
A solution has a pOH of 3. Calculate the pH, determine [OH⁻], and classify the solution as acidic, basic, or neutral.
pH = 11; [OH⁻] = 1×10⁻³ M; basic
A solution has [H⁺] = 1×10⁻² M. Find the pH, pOH, and [OH⁻]
pH = 2; pOH = 12; [OH⁻] = 1×10⁻¹² M
A balloon contains 3.0 mol of gas. If moles are increased to 6.0 mol at constant temperature and pressure, what happens to the volume and what law explains this?
Volume doubles; Avogadro's Law (V₁/n₁ = V₂/n₂)
A gas sample has a volume of 8.2 L at 400 K. If it contains 2.0 mol, what is the pressure? (R = 0.0821)
P = (2.0 × 0.0821 × 400) / 8.2 ≈ 8.0 atm
For 2CO(g) + O₂(g) → 2CO₂(g): if 3.0 moles of CO burn at STP, what volume of CO₂ is produced?
67.2 L