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Ch.1 - Introduction: Matter, Energy, and Measurement
Chapter 1, Problem 92a

Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (a) Air and water are both elements.

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1
Understand the definition of an element: An element is a pure substance consisting of only one type of atom, characterized by its atomic number.
Recognize that air is a mixture: Air is composed of various gases, primarily nitrogen (N_2) and oxygen (O_2), along with smaller amounts of other gases like argon (Ar) and carbon dioxide (CO_2).
Identify that water is a compound: Water (H_2O) is a chemical compound made up of two hydrogen atoms bonded to one oxygen atom.
Evaluate the statement about air: Since air is a mixture of different gases and not a single type of atom, it is not an element. Therefore, the statement 'Air is an element' is false.
Evaluate the statement about water: Since water is a compound made of hydrogen and oxygen atoms, it is not an element. Therefore, the statement 'Water is an element' is false.

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Key Concepts

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

Elements vs. Compounds

Elements are pure substances that cannot be broken down into simpler substances by chemical means. They consist of only one type of atom, such as oxygen (O) or hydrogen (H). Compounds, on the other hand, are substances formed when two or more elements chemically bond together, like water (H2O), which is made of hydrogen and oxygen.
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Homonuclear vs. Heteronuclear Compounds

Composition of Air

Air is a mixture of gases, primarily nitrogen (about 78%) and oxygen (about 21%), along with trace amounts of other gases like carbon dioxide and argon. Unlike elements, mixtures can be separated into their individual components without chemical reactions. Therefore, air is not an element but a complex mixture.
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Matter Composition

Water as a Compound

Water is classified as a compound because it consists of two hydrogen atoms covalently bonded to one oxygen atom (H2O). This chemical structure is distinct from elements, as it involves the combination of different types of atoms. Understanding this distinction is crucial for accurately categorizing substances in chemistry.
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Related Practice
Open Question
A 30.0-cm-long cylindrical plastic tube, sealed at one end, is filled with acetic acid. The mass of acetic acid needed to fill the tube is found to be 89.24 g. The density of acetic acid is 1.05 g/mL. Calculate the inner diameter of the tube in centimeters.
Textbook Question

Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry. (a) Consider a piece of gold jewelry that weighs 9.85 g and has a volume of 0.675 cm3. The jewelry contains only gold and silver, which have densities of 19.3 and 10.5 g/cm3, respectively. If the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percentage of gold (by mass) in the jewelry. (b) The relative amount of gold in an alloy is commonly expressed in units of carats. Pure gold is 24 carat, and the percentage of gold in an alloy is given as a percentage of this value. For example, an alloy that is 50% gold is 12 carat. State the purity of the gold jewelry in carats.

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Open Question
Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (e) When yellow stains in a kitchen sink are treated with bleach water, the disappearance of the stains is due to a chemical change.
Textbook Question

Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (b) All mixtures contain at least one element and one compound.

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Textbook Question

Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (c) Compounds can be decomposed into two or more other substances; elements cannot.

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Textbook Question

Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (d) Elements can exist in any of the three states of matter.

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