Follow-up:

Use stronger acids like a 10 % solution of Hydrochloric Acid ( stir carefully do not shake ) and just look to see if you observe any changes in your samples. You may use an eye dropper to add the diluted HCL a drop at a time. Have baking soda ready in case of a spill.

Observation Questions:

Analysis Questions:

1. Which rock type was affected by the carbonic acid? Support your answer with examples from your data. Rocks containing calcium carbonate like limestone and marble should be decomposed faster. Students should look to their observations.
2. Which samples showed signs of mechanical weathering? Give examples. Samples with the greatest surface area exposed should be broken down faster and disintegrate more. Samples like shale or mudstone should break a part first. Limestone and marble and even basalt will leave dust in the containers. Again students should consult their observations.
3. Which samples showed signs of chemical weathering? Give examples. The samples containing calcium carbonate and clay minerals should chemically weather first. Also the first formed igneous rocks like olivine and basalt should chemically weather before rocks that take longer to crystallize and contain higher concentrations of quartz. Again students should consult their measurements and observations.
4. How did time relate to the rate of weathering? Give examples. Longer time should result in greater weathering of all kinds. You may replace the carbonic acid and continue to shake the jars until the end of the year and save a sample to show next years class. Put them out and let the students guess what happened to the rocks.
5. Which rock type was least effected by the carbonic acid? Support with an example. The granite should be least affected or any rock with a high quartz content.
6. How does weathering relate to the Bowen's Reaction Series for igneous rock? The igneous rocks that are the first to crystallize are the first to show signs of weathering. The magma melts at a high temperature and their minerals cool at a higher temperature. Fro example Basalt will weather long before granite. You may ask the students to find examples of weathered mountains and relate them to this information.