Science 10

Lab Investigation

Title: Some Say I'm Just Too Blunt!

Background: Chemistry is literally everywhere - inside us and all around us. An obvious example of this ties in with Weathering; the erosion of limestone and marble building facades and statuary.

Process:

1. Make a proposal sketch of a sculpture you will make from a half stick of board chalk.

2. Once the design is approved, create the sculpture. Use any reasonably sharp point, e.g., the end of a compass or a straightened out paper clip. Since ideas may change during the sculpting process (the chalk breaks into tiny pieces!), make a detailed sketch of your finished creation. This will be an important reference for later.

3. In lab, obtain a medium test tube and clean it with water and a test tube brush. Make sure the test tube's outside is clean and dry. Use a china marker to identify it as yours.

4. The students assigned to Section 1 will add enough water to 1/2 fill a medium test tube. Those in Section 2 will make a 50 % vinegar solution by adding equal amounts of water and vinegar to the medium test tube until it is 1/2 full. Students in Section 3 will fill a medium test tube 1/2 full of plain vinegar.

5. Place your chalk sculpture in the solution and stand your test tube in the 400 ml beakers set aside as test tube stands. Let the chalk sit in the liquid for 50 minutes.

6. Carefully pour out liquid but hold back the chalk sculpture. Vinegar is a safe, common cooking and cleaning agent and no hand protection is needed. Note: all the sculptures from each Section must be brought to the same spot in the lab for evaluation. Carefully lay your sculpture on a piece of paper towel. Next to the sculpture, place your sketch from Step 2.

Questions:

1. Compare the sculptures with their sketches from Step 2. Based on changes in the look of the sculptures, categorize the solutions according to their weathering "power".

2. Reword your ideas from Q 1. in terms of the rate of weathering caused by the solutions.

3. What are concerns created by the weathering of building facades and statuary?

Go to: http://pubs.usgs.gov/gip/acidrain/5.html and please print the image of the damaged roof Antefixes.

Go to: http://ga-mac.uncc.edu/faculty/haas/geol3190/termpap/earwood/ and please print the image of the sandstone statue affected by acid rain.

4. Suggest two ways this type of weathering can be minimized. Ideas can be found in the information at: http://members.aol.com/profchm/acidrain.html