Indicate whether each of these is a pure substance or mixture.
a. pulp-free orange juice – mixture
b. ibuprofen – pure substance
c. chlorine gas – pure substance
d. Tootsie-pop lollipop – mixture
The correct answer and explanation is:
Correct Answers:
a. Pulp-free orange juice – Mixture
b. Ibuprofen – Pure substance
c. Chlorine gas – Pure substance
d. Tootsie-pop lollipop – Mixture
Explanation:
A pure substance is a material made of only one type of particle with a consistent and fixed composition. It can be an element or a compound. A mixture consists of two or more substances physically combined, with variable composition and properties that depend on the mixture’s components.
Pulp-free orange juice is a mixture because it contains water, natural sugars, citric acid, vitamin C, and other dissolved compounds. Even though the pulp has been removed, the liquid still contains a variety of substances that are not chemically bonded. These components can be physically separated, confirming it is a mixture.
Ibuprofen is a pure substance when considered in its chemically pure form. It is a compound with the specific chemical formula C₁₃H₁₈O₂. All particles of pure ibuprofen are identical molecules. It has a definite composition and consistent properties throughout, meeting the criteria of a pure substance.
Chlorine gas is a pure substance because it consists entirely of chlorine molecules (Cl₂). It is an element in its gaseous form and is made up of identical diatomic molecules. It has a uniform and fixed composition, qualifying it as a pure substance.
Tootsie-pop lollipop is a mixture. It contains many components such as sugar, corn syrup, flavoring, coloring, and a chewy chocolate center. These are physically combined but not chemically bonded. The properties vary from the outer candy shell to the inner filling, and the ingredients can be identified separately, making it a mixture.
Understanding the difference between mixtures and pure substances helps in chemistry for classification, analysis, and determining how substances interact in reactions.