A titration is a procedure for determining the concentration of a solution by al

Question

A titration is a procedure for determining the concentration of a solution by allowing it to react with another solution of known concentration (called a standard solution). Acid base reactions and oxidation-reduction reactions are used in titrations. For example, to find the concentration of an HCI solution (an acid), a standard solution of NaOH (a base) is added to a measured volume of HCI from a calibrated tube called a buret. An indicator is also present and it will change color when all the acid has reacted. Using the concentration of the standard solution and the volume dispensed. we can calculate molarity of the HCI solution. Part A A volume of 40.0mL of aqueous potassium hydroxide (KOH) was titrated against a standard solution of sulfuric acid (H2SO4). What was the molarity of the KOH solution if 19.7 mL of 1.50 M H2SO4 was needed? The equation is Part B Redox titrations are used to determine the amounts of oxidizing and reducing agents in solution. For example, a solution of hydrogen peroxide. H2O2, can be titrated against a solution of potassium permanganate. KMnO4. The following equation represents the reaction: A certain amount of hydrogen peroxide was dissolved in 100. mL of water and then titrated with 1.68 M KMnO4. What mass of H2O2 was dissolved if the titration required 20.3 mL of the KMnO4 solution?

Explanation / Answer

A)

1000 mL = 1 L
M = mol/L

.0197 L x (1.5 mol H2SO4/ 1 L) x (2 mol H+/ 1 mol H2SO4) x (1 mol OH-/1 mol H+) x (1 mol KOH/ 1 mol OH-) = .0591 mol KOH

so you have .0591 mol KOH in 40 mL of water

M KOH = .0621/.05 = 1.4775 M

B)

C(KMnO4) x V(KMnO4) = 2 x C(H2O2) x V(H2O2)

C(H2O2) = C(KMnO4) x V(KMnO4) / ( 2 x V(H2O2) )
C(H2O2) = 1,68 x 20,3 / ( 2 x 100 )
C(H2O2) = 0,171 mol/L

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