Question

Question 1

A monoprotic solid acid, Potassium Hydrogen Phthalate (aka, KHP), KHC₈H₄O₄, (molar mass = 204.22 g/mol) is used to standardize solutions of NaOH. (see KOTZ p. 218, and problem 72.)

A student weighs out 1.3009 g of KHP and dissolves it in some water. The student then performs a titration with a solution of unknown concentration of NaOH, using 41.20 mL to reach the equivalence point.

What is the Molarity of the NaOH solution?

Question 2

25.00 mL of a H₂SO₄ solution is titrated with a 0.184 M NaOH solution. It required 34.23 mL of the NaOH solution to reach the equivalence point.

What is the molarity of the H₂SO₄ solution?

H₂SO_{4 (aq)} + 2 NaOH _(aq) --> Na₂SO₄ (aq) + 2 H₂O _(l)

NOTE: Sulfuric Acid is a diprotic acid and therefore requires two moles of NaOH for each mole of H₂SO₄ in the reaction.

Question 3

As a chemist, you are requested to identify a solid unknown monoprotic acid, HA. (The general formula HA is often used to represent any monoprotic acid.)

You take 0.1999 g of this solid and titrate it with 10.59 mL of 0.1546 M NaOH to reach the equivalence point.

What is the molar mass of this unknown acid?

HA _(aq) + NaOH _(aq) --> NaA _(aq) + H₂O _(l)

Question 4

Potassium Permanganate, KMnO₄, is a common strong oxidizing agent, but it is also a very nice titrant for redox reactions because it is a dark purple solution but when it is reduced to Mn²⁺, it is colorless. Therefore, the equivalence point is indicated by the lasting purple/pink color of the solution.

Suppose 35.00 mL of a solution of Fe(NO₃)₂ is titrated with 28.65 mL of 0.0254 M KMnO₄, reaching the equivalence point.  

What is [Fe²⁺] in the iron (II) solution?  

Answer 1