# Video: Identifying the Common Laboratory Test Used to Prove Carbon Dioxide Is a Product of a Reaction in a Set of Test Names

Dry calcium carbonate is placed in a crucible and heated over a flame. After cooling, the mass of the crucible and contents is determined. Recorded Data: Mass of crucible = 14.01 g. Mass of crucible and calcium carbonate = 64.05 g. And the mass of crucible and product (after heating) = 42.05 g. To prove that carbon dioxide is a product in this reaction, which common laboratory test could be used? [A] The pop test. [B] The limewater test. [C] The cobalt chloride test. [D] The glowing splint test. [E] the oil drop test.

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### Video Transcript

Dry calcium carbonate is placed in a crucible and heated over a flame. After cooling, the mass of the crucible and contents is determined. And we are given some recorded data. The mass of the crucible is 14.01 grams. The mass of crucible and calcium carbonate: 64.05 grams. And the mass of crucible and product after heating: 42.05 grams. To prove that carbon dioxide is a product in this reaction, which common laboratory test could be used? (A) The pop test. (B) The limewater test. (C) The cobalt chloride test. (D) The glowing splint test. Or (E) the oil drop test.

In this question, calcium carbonate, or CaCO3, is heated. When a metal carbonate, such as calcium carbonate, is heated, it breaks apart into a metal oxide, in this case, calcium oxide, and carbon dioxide gas. This breaking apart of one reactant into more than one product is called a decomposition reaction. A lot of energy is required to break apart the metal carbonate. And this energy is supplied through heat energy from a Bunsen burner. We do not need to consider the mass data given to us in this question because we are merely asked how we can prove that carbon dioxide is a product in this reaction.

The pop test tests for the presence of hydrogen gas. When hydrogen gas is present, a burning splint will make a sudden popping sound. This is because hydrogen gas is flammable. And in the presence of oxygen gas in the air and the heat from the burning splint, a mini explosion occurs. The cobalt chloride test tests for liquid water or moisture in the air. Moisture in the air is really tiny liquid water droplets. Cobalt chloride on a piece of paper will turn from blue to pink in the presence of water. The glowing splint test is used to test for oxygen gas. When oxygen gas is present, the glowing splint will burst into flame. The oil drop test was used in 1909 by scientists to determine the charge on one electron.

So, options (A), (C), (D), and (E) will not help us prove that carbon dioxide is a product in this reaction. To test for the presence of a gas which is thought to be carbon dioxide, the gas is allowed to bubble through a limewater solution. Limewater is an aqueous solution of calcium hydroxide or CaOH2. When calcium hydroxide reacts with carbon dioxide gas, calcium carbonate and water are produced. Calcium carbonate is a white solid. This precipitate consists of tiny white particles dispersed throughout the liquid, making the liquid look milky. So, in the limewater test, the clear liquid turns milky in the presence of carbon dioxide gas.

So, the correct answer is option (B). The limewater test will prove that carbon dioxide is a product in this reaction.