Ch.1 - Introduction: Matter, Energy, and Measurement

Brown - Chemistry: The Central Science 14th Edition

Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook

Brown 14th Edition

Ch.1 - Introduction: Matter, Energy, and Measurement

Problem 13a,b

Chapter 1, Problem 13a,b

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) air (b) chocolate with almond

Verified step by step guidance

Step 1: Understand the definitions. A pure substance consists of a single type of element or compound, with a uniform and definite composition. A mixture contains two or more substances that are not chemically combined and can be either homogeneous or heterogeneous.

Step 2: Analyze 'air'. Air is composed of various gases such as nitrogen, oxygen, carbon dioxide, and others. Since these gases are mixed together without chemical bonding, air is a mixture.

Step 3: Determine the type of mixture for 'air'. The composition of air is uniform throughout, meaning it is the same in every sample. Therefore, air is a homogeneous mixture.

Step 4: Analyze 'chocolate with almond'. This consists of chocolate and almond pieces mixed together. Since these components are not chemically bonded and can be physically separated, it is a mixture.

Step 5: Determine the type of mixture for 'chocolate with almond'. The composition is not uniform, as you can see and separate the almond pieces from the chocolate. Therefore, chocolate with almond is a heterogeneous mixture.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Pure Substances

A pure substance consists of a single type of particle and has a uniform and definite composition. Examples include elements like oxygen and compounds like water. Pure substances have consistent properties throughout, such as boiling and melting points, which distinguish them from mixtures.

Mixtures

Mixtures are combinations of two or more substances that retain their individual properties. They can be classified as homogeneous, where the composition is uniform throughout (like saltwater), or heterogeneous, where the composition varies (like a salad). The components in a mixture can often be separated by physical means.

Homogeneous vs. Heterogeneous Mixtures

Homogeneous mixtures have a uniform composition and appearance, meaning that the different components are not distinguishable. In contrast, heterogeneous mixtures contain visibly different substances or phases, allowing for the identification of individual components. Understanding this distinction is crucial for classifying mixtures correctly.

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Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (c) aluminium

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Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (d) iodine tincture.

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Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) milk

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(a) How many significant figures should be reported for the volume of the metal bar shown here?

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The photo below shows a picture of an agate stone. Jack,who picked up the stone on the Lake Superior shoreline andpolished it, insists that agate is a chemical compound. Ellenargues that it cannot be a compound. Discuss the relativemerits of their positions.

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