chemistry

Performance Task # 4

Using the techniques of titration in the analysis of a household acid

Titration is a technique that can be used to determine either the volume or concentration of a reactant if the other reactant’s volume and concentration is known. This is true of neutralization reactions most commonly acid-base reactions.

In a titration, one solution called the titrant is slowly added to the other solution. The stoichiometric point of complete neutralization is called the Equivalence Point. This is when the moles of acid have s been neutralized with an equivalent amount of moles of base. This can be easily shown with a stoichiometric ratio.

A chemical method tells you when to stop the titration. An acid-base indicator will change color at a certain acidity and if chosen correctly, this color change denotes the end of titration. The color change of an indicator determines the end point of the titration.

In order to demonstrate this, control, left click on the following link: https://www.youtube.com/watch?v=5BZ0MPIgeEE

After watching the video, you noticed they determined the unknown using the simple formula:

Molarity acid X Volume acid = Molarity base X Volume base

For example: If it took 22.0ml of an unknown Ca(OH)2 solution to completely neutralize 10.0ml of 0.5 Molar H2SO4 ,, the Molarity of the Ca(OH)2 would be:

Molarity acid X Volume acid = Molarity base X Volume base

(0.5M) X (10ml) = ( ? ) X (22ml)

Therefore the Molarity of the Ca(OH)2 base = 0.28 Molar

Determining the % acidity in a household product

Example problem: If it takes 6.8ml of a 0.05 Molar NaOH solution to completely neutralize the Vitamin C (Ascorbic Acid = HC6H7O6) in a 3.0 multi-vitamin tablet. What is the % Vitamin C in the tablet?

Balanced neutralization reaction: NaOH + HC6H7O6 --- NaC6H7O6 + H2O

(Ascorbic Acid)

6.8ml of NaOH 0.05 moles NaOH 1 mole HC6H7O6 176 grams ---------------------- x ---------------------- x -------------------------- x ------------------ = _____grams

1 1000ml 1 mole NaOH 1 mole of HC6H7O6

Therefore the grams of Ascorbic Acid (Vitamin C) = 0.060 g

grams of Vitamin C = 0.060g

----------------------------------------------- x 100 = 2% Vitamin C in the tablet

grams of tablet = 3.0g

Performance Task 4 Data

Part 1: Determining the Molar concentration of NaOH using 0.5 Molar HCl:

a) Amount of HCl = 10.0ml

b) Amount of NaOH needed for neutralization = 31.0 ml

c) Molarity of the NaOH = ___________ Molar

(show calculations, you can use this NaOH molarity for the rest of the calculations where necessary)

Part 2: Determining the acidity of a household product

Group 1 (last name initial ___ to last name initial ____) Analysis of Vinegar

Group 2 (last name initial ____ to last name initial ____) Analysis of Lemon Juice

Group 3 (last name initial ____ to last name initial ____) Analysis of Apple Juice

Group 4 (last name initial ____ to last name initial ____) Analysis of Grape Juice

Group 1: Determining the % Acetic Acid (HC2H2O3) in Vinegar:

Balanced neutralization reaction: NaOH + HC2H3O2 ----- NaC2H3O2 + H2O

(acetic acid)

a) Volume of vinegar = 10.0ml

b) Mass of vinegar = 10.9g

c) Density of vinegar = _______g/ml

d) Amount of NaOH to neutralize = 62.1ml

e) Grams of Acetic Acid in vinegar = ______grams

f) % Acetic Acid in vinegar = ________%

(Show all Calculations)

Group 2: Determining the % Citric Acid (H3C6H5O7) in Lemon Juice

Balanced neutralization reaction: 3NaOH + H3C6H5O7 ------ Na3C6H5O7) + 3H2O

(Citric Acid)

a) Volume of Lemon Juice = 10.0ml

b) Mass of Lemon Juice = 11.1g

c) Density of Lemon Juice = _______g/ml

d) Amount of NaOH to neutralize = 63.9ml

e) Grams of Citric Acid in Lemon Juice = ______grams

f) % Citric Acid in Lemon Juice = ________%

(Show all calculations)

Group 3: Determining the % Malic Acid (H2C4H4O5) in Apple Juice

Balanced neutralization reaction: 2NaOH + H2C4H4O5 --------- Na2C4H4O5 + 2H2O

(Malic Acid)

a) Volume of Apple Juice = 10.0ml

b) Mass of Apple Juice = 10.1g

c) Density of Apple Juice = _______g/ml

d) Amount of NaOH to neutralize = 19.4 ml

e) Grams of Malic Acid in Apple Juice = ______grams

f) % Malic Acid in Apple Juice = ______%

(Show all calculations)

Group 4: Determining the % Tartaric Acid (H2C4H4O6) in Grape Juice

Balanced Neutralization reaction: 2NaOH + H2C4H4O6 ------ Na2C4H4O6 + 2H2O

(Tartaric Acid)

a) Volume of Grape Juice = 10.0ml

b) Mass of Grape Juice = 10.3g

c) Density of Grape Juice = _____ g/ml

d) Amount of NaOH to neutralize = 8.2 ml

e) Grams of Tartaric Acid in Grape Juice = ______grams

f) % Tartaric Acid in Grape Juice = ______%

(Show all calculations)