CHEMICAL WEATHERING ACTIVITY LIMESTONE ROCK Materials: limestone chalk vinegar pipette
DIRECTIONS 1. Observe chalk and limestone and record your observations, including any similarities or differences. 2. Google and record information about the the following: * Composition of limestone rock * Composition of chalk * Composition of vinegar * Composition of carbonic acid * Cause of fizzing when vinegar applied to chalk/rock
Summarization of Research * Compositions of limestone and chalk * Chemical formulas * Similarities between chalk and limestone * Formation of limestone rock * Process of carbonic acid formation * Composition of vinegar * Similarities between vinegar and carbonic acid * Explain why rock/chalk fizzes when vinegar is applied. * Process of how limestone rock is weathered chemically
Scientific Process 1. State the problem to be solved, in the form of a question to be answered. 2. Make a hypothesis about what will happen if vinegar is added to chalk and limestone. 3. Write a Two-Part Experiment (List Materials & Write a Procedure) 4. Record and Analyze Results: * Data Table * Graph 5. Conclusion: state if hypothesis was right or wrong and why.
TEACHER NOTES Composition of Limestone: CaCO 3 Mainly made up of the minerals calcite and aragonite – which have crystal forms of calcium carbonate (CaCO 3 ). Formation of Limestone: Skeletal fragments of tiny marine organisms such as coral, that accumulate on seafloor. Once seafloor no longer seafloor, but sedimentary rock layers. The organisms are crushed in the layers to form limestone.
TEACHER NOTES Composition of Chalk: CaCO 3 Composed of calcium carbonate formed from crushed bodies of tiny sea creatures that accumulate on ocean floor. Composition of Carbonic Acid: H 2 CO 3 Made up of solutions of carbon Dioxide in water. It forms when CO 2 in the air mixes with rainwater during chemical weathering. H 2 CO 3 reacts with calcium carbonate CaCO 3 in limestone and dissolves the rock. Composition of Vinegar Acetic acid CH 3 COO 4 – a weak acid similar to carbonic acid H 2 COO 3
LAB – Chemical Weathering of Limestone OBJECTIVE: Students will simulate the chemical weathering of limestone by using vinegar to represent carbonic acid, and chalk to represent limestone. Students will observe how chalk fizzes and dissolves when a dropper full of vinegar is applied to surface. Limestone will fizz, but will take several weeks to dissolve. The fizzing is the release of carbon dioxide into the air. If limestone is submerged in vinegar, it will dissolve much quicker(3-4 weeks). In nature, it takes 1000’s of years for the rock to dissolve and form Karst topography like caves.