Objective: To quickly be able to test rock specimens and identify them and to also learn about the chemical properties of rocks.
Standards: Properties of Earth Materials (physical and chemical properties of rocks).
Materials: small sampling of various rocks including limestone or marble and two ounces (60 mL) of lemon juice (or vinegar).
(1) Pour lemon juice over the various rocks.
(2) Observe and discuss.
Science Behind It: Students will be able to quickly identify samples of limestone and marble because the lemon juice will “bubble” or effervesce on the surfaces of these rocks. This occurs because limestone contains calcium carbonate which is an alkaline substance. When the acidic lemon juice is added, it reacts with the alkaline of the limestone to produce carbon dioxide, therefore resulting in the appearance of bubbles. Marble is a rock formed from limestone and will react with the acid the same way as the limestone. Similar results will also occur when adding lemon juice to chalk, as it is also made of limestone.