Chem 0200 Quiz 1

The solubility product of magnesium hydroxide, Mg(OH)₂ in pure water is 1.96 × 10^^-11 M³ at room temperature. Calculate its molar solubility.

• 0.00017 mol L^-1

• 0.003 mol L^-1

• 1.022 mol L^-1

• 1.598 mol L^-1

A 0.10 M sodium hydroxide solution was prepared and titrated against 25 mL of 0.55 M formic acid, HCOOH. Which of the following is true if 25 mL of the base are added to the acid?

• 0.0035 moles of formate ions are produced from the reaction

• The mixture shows an alkaline pH

• The initial pH before titration is approximately 10

• The resultant solution is acidic

A student prepares a buffer solution in the lab by adding together 0.18 mol H₂PO₄^- and 0.08 mol HPO₄^2-. What amount of H₂PO₄^- will be present after 2.0 g of H₂SO₄ is added to the solution? Molar mass of H₂SO₄: 98 g mol^-1

• 0.07 mol

• 0.18 mol

• 0.22 mol

• 0.04 mol

A 0.57 mol L^-1 calcium chloride is prepared and some lead chloride, PbCl₂ is added to the solution. Which of the following represents the chloride ion concentration in the resultant solution given that the molar solubility of PbCl₂ is b mol L^-1?

• (b + 0.13) mol L^-1

• (b + 0.57) mol L^-1

• (0.57 + 2b) mol L^-1

• (2b + 1.14) mol L^-1

Which of the following statements are true about the dissociation of water:

H₂O (l) ⇌ H⁺ (aq) + OH^- (aq) ? ΔH = 96 kJ

(i) The value of the ionic produce K_sp increases with a rise in temperature

(ii) An increase in temperature will shift the equilibrium in the forward direction

(iii) the pH of water decreases as temperature increases.

• (i) and (ii) only

• (ii) and (iii) only

• (i) and (iii) only

• (i), (ii) and (iii)

Some lead nitrate solution was added to a solution of sodium sulfate and a white precipitate was seen. Given that the solubility product of lead sulfate is 6.3 x 10⁷, which of the following statements is correct?

• The solubility product far exceeded the reaction quotient of the mixture

• The solubility product was less than the reaction quotient

• The reaction quotient of the mixture was less than 6.3 x 10⁷

• The reaction quotient was calculated by finding the sum of the ions present in the reaction mixture

The solubility product of magnesium bromide, MgBr₂ in pure water is 2.6 x 10^-5 at room temperature. Calculate its molar solubility.

• 0.003 mol L^-1

• 0.019 mol L^-1

• 1.022 mol L^-1

• 1.598 mol L^-1

Analysis of a silver sulfate, Ag₂SO₄ aqueous solution revealed the concentration of sulfate ion to be 0.025 mol dm^-3 at 10°C. What will be the K_sp of Ag₂SO₄ at this temperature?

• 2.07 x 10^-5 mol³ dm^-9

• 6.25 x 10^-5 mol³ dm^-9

• 8.11 x 10^-6 mol³ dm^-9

• 4.52 x 10^-8 mol³ dm^-9

A sample of lithium carbonate, Li₂CO₃ was added to a 0.07 mol L^-1 lithium nitrate solution at 25°C and stirred. Which of the following correctly expresses the lithium ion concentration in the new solution given that the molar solubility of Li₂CO₃ is y mol L^-1?

• (y + 0.07) mol L^-1

• (0.07 + 3y) mol L^-1

• (y + 0.14) mol L^-1

• (0.07 + 2y) mol L^-1

A 1 L solution of sodium hydroxide gave a reading of 12.8 when checked with a pH meter. What concentration of sodium hydroxide was used to prepare the solution?

• 1.026 mol

• 0.063 g

• 1.940 M

• 0.063 M