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 HC1 solution (an acid), a standard solution of NaOH (a base) is added to a measured volume of HCl 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 2KOH(aq) + H2SO4(aq) right arrow K2SO4(aq) + 2H2O(l) Express your answer with the appropriate units. molarity =0.000001 M Part B Redox titrations are used to determine the amounts of oxidizing and reducing agents in solution For examp4e. a solution of hydrogen peroxide. H2O2, can be titrated against a solution of potassium permanganate, K Mn04 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 20.3mL of the KMnO4 solution? Express your answer with the appropriate units. mass of H2O2=Value Units

Explanation / Answer

Part A

VKOH = 40 ml

VH2SO4 = 19.7 ml

[H2SO4] = 1.50M

[KOH] = ?

molH2SO4= 1.5mol/1000ml x 19.7ml = 0.0295mol

2 mol KOH ----1mol H2SO4

X ------ 0.0295 molH2SO4

X = 0.059 mol

[KOH] = 0.059/40 ml x 1000ml/1l = 1.48 M

Part B

nKMnO4 = 1.68mol/1000mL x 20.3ml = 0.03410 mol

2 molKMnO4 ------ 1mol H2O2

0.03410 mol KMnO4-------- X = 0.01705 molH2O2

H2O2 = 34g/mol

gH2O2 = 34g/mol x 0.01705 molH2O2 = 0.5797 g

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