Problem 68 - Chemistry: The Central Science

Question

Which of the following would you characterize as a pure or nearly pure substance? (a) baking powder; (b) lemon juice; (c) propane gas, used in outdoor gas grills; (d) aluminum foil; (e) ibuprofen; (f) bourbon whiskey; (g) helium gas; (h) clear water pumped from a deep aquifer.

Step-by-Step Solution

Answer

The substances that can be characterized as pure or nearly pure are: propane gas (c), aluminum foil (d), ibuprofen (e), and helium gas (g).

Step 1: Define the criterion for a pure substance

A pure or nearly pure substance is a material that consists of only one type of particle (either atoms or molecules) and has a fixed composition and distinct properties.

Step 2: Determine if the substance is pure or nearly pure

We will analyze each substance and decide whether it meets the criterion for being a pure or nearly pure substance. a) Baking powder: Baking powder is a mixture of different substances, such as sodium bicarbonate and cream of tartar. So, it is not a pure substance. b) Lemon juice: Lemon juice is a mixture of water, citric acid, and other substances. Therefore, it is not a pure substance. c) Propane gas: Propane gas is a compound made up of carbon and hydrogen atoms. It is used as a fuel in outdoor gas grills and is nearly pure. So, it can be considered a pure substance. d) Aluminum foil: Aluminum foil is made of almost pure aluminum. Although there might be traces of other elements, it is considered nearly pure and can be characterized as a pure substance. e) Ibuprofen: Ibuprofen is a compound consisting of hydrogen, carbon, and oxygen atoms. As a pharmaceutical drug, it is manufactured to be almost pure, so it can be considered a nearly pure substance. f) Bourbon whiskey: Bourbon whiskey is a mixture of alcohol, water, and various flavor compounds. Therefore, it is not a pure substance. g) Helium gas: Helium gas is an element that consists of only helium atoms. It can be obtained with a high degree of purity, so it is a pure substance. h) Clear water pumped from a deep aquifer: Although the water pumped from a deep aquifer is relatively clean and free of contaminants, it still contains dissolved minerals. Therefore, it is not a pure substance.

Step 3: Conclusion

From the analysis, we can conclude that the following substances can be characterized as pure or nearly pure: - Propane gas (c) - Aluminum foil (d) - Ibuprofen (e) - Helium gas (g)