Virtual Try This Activity
Comparing Two Acids
Purpose
Do all acids behave similarly?
icon Science Skills
checkPerforming and Recording
checkAnalyzing and Interpreting

Materials
The following materials are shown in the photographs of this virtual investigation.
  • 1.00-mol/L ethanoic acid
  • 2, 10-mL graduated cylinders
  • 2 eyedroppers
  • 2, 5-cm lengths of magnesium ribbon
  • 2, 50-mL beakers
  • 2 test tubes (capacity around 5 mL)
  • pH paper (or pH meter)
  • 1.00-mol/L hydrochloric acid
  • test tube rack
  • scissors
  • grease pencil (or waterproof marker)
  • stopwatch (or clock)
  • conductivity meter
  • forceps or tweezers

Click on photos to enlarge.

icon CAUTION!
Use gloves, safety glasses, and a lab apron for this activity.

Procedure

step 1:

Prepare a data table with two columns. Use the names of the two acid solutions listed in the materials as the headings for your table.

 
step 2:

Use the grease pencil or waterproof marker to label one of the test tubes "Ethanoic Acid." Place the test tube into the test tube rack.

 
step 3:

Transfer exactly 5.00 mL of ethanoic acid to one of the graduated cylinders. Use an eyedropper to ensure the meniscus is at the 5.00-mL mark on the cylinder.

Measuring 5 mL of ethanoic acid

 
step 4:

Transfer the ethanoic acid in the graduated cylinder to the “Ethanoic Acid” test tube.

Labelled tubes containing respective acids

 
step 5:

Transfer enough of the ethanoic acid from the test tube to cover the bottom of one of the 50-mL beakers. Use the conductivity meter to test the solution. Record your observations in your data table. Use the acid in the beaker to measure the pH. Place one of the strips of pH paper into the remaining solution and record the pH of the solution in a data table. (If you are using a pH meter, you may have to use a larger volume of acid in the beaker to cover the electrode at the bottom of the meter. Ensure that you rinse the electrode before testing the pH of the second solution.)

Ethanoic acid in beaker
Results: Ethanoic acid undergoing conductivity test
  Ethanoic acid undergoing pH test
  pH results of ethanoic acid

 
step 6:

Repeat steps 2 to 5 using the hydrochloric acid solution.

Results: Hydrochloric acid undergoing conductivity test
  pH results (far left) of hydrochloric acid

 
step 7:

Place a strip of magnesium into each of the test tubes. Record the initial response of the magnesium to the acid and the length of time until a reaction no longer occurs in each of the test tubes. Estimate the amount of magnesium remaining in each test tube.

Results: Initial response of hydrochloric acid (left) and ethanoic acid (right)
  Response of hydrochloric acid (left) and ethanoic acid (right) after 20 min

 

Analysis
Use the data collected to prepare a list of similarities and differences between ethanoic acid and hydrochloric acid.