A+ Tutorial/Guide for Chemistry Lab assignment.

** NOTE: Use this to help you understand your lab assignment and solve the questions. All formulas and work shown. I used pH 4.5 for Orange Juice, and 7.0 for Milk, 30 g and 35 ml for density of vinegar, and 2.0 pH for vinegar. But you can use your own values and get help using this.

Experiment UTA 1451-400

Acids and Bases

Part A: Measuring the pH of solutions

1. Complete the following table. Show all work below the table.

SolutionH3O+OH-pOHAcidic, Basic, or Neutral

Orange Juice

Milk

Calculations for Orange Juice:

Calculations for milk:

Part B: Density of Vinegar

1. Calculate the density of distilled white vinegar. Show your all work.

2. The concentration 5% (w/v) means that 5 g of acetic acid (solute) are present in 100 mL of the solution. Using the density you determined in the previous problem, determine the mass of water (solvent) in 100 mL of the solution. Follow the guided steps below.

a. Determine the mass of 100. mL of the solution by using the density. Express your answer in three significant figures.

b. The mass of the solution should be the sum of the mass of the solvent and the mass of the solute. Now determine the mass of the solvent.

Part C: Determination of Ka of Acetic Acid

1. The concentration of distilled white vinegar is written as 5% (w/v) of acetic acid (CH3COOH). Convert the concentration in the unit of molarity. Express your answer in four significant figures. Show your work here.

2. Calculate the concentration of hydronium ions [H3O+] from the measured pH values. Express your answer in two significant figures. Show your all work.

3. Using the initial concentration of CH3COOH (from Problem 4) and the equilibrium concentration of H3O+ calculated (from Problem 5), complete the reaction table for vinegar. Then, calculate the acidity constant. Show your work.

Reaction Table: CH3COOH (aq) + H2O(l) ?CH3COO?(aq)+ H3O+(aq)

Initial

Change

Equilibrium

Using the concentrations at equilibrium, the acidity constant (Ka) is calculated as

1. The acidity constant of acetic acid is 1.8x10^-5. Calculate the % error of the measured Ka value.