Chapter 3

A Create a table that describes the three common states of matter in terms of their shape, volume, and compressibilit

Describe the characteristics that identify a sample of matter as a substance.

Classify each of the following as a physical or a chemical proper \begin{equation} \begin{array}{l}{\text { a. Iron and oxygen form rust. }} \\ {\text { b. Iron is more dense than aluminum. }} \\ {\text { c. Magnesium burns brightly when ignited. }} \\ {\text { d. Oil and water do not mix. }} \\ {\text { e. Mercury melts at }-39^{\circ} \mathrm{C} \text { . }}\end{array} \end{equation}

From a laboratory process designed to separate water into hydrogen and oxygen gas, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How much water was originally involved in the process?

Challenge 106.5 g of HCl(g) react with an unknown amount of \(\mathrm{NH}_{3}(\mathrm{g})\) to produce 157.5 \(\mathrm{g}\) of \(\mathrm{NH}_{4} \mathrm{Cl}(\mathrm{s})\) . How many grams of \(\mathrm{NH}_{3}(\mathrm{g})\) reacted? Is the law of conservation of mass observed in the reaction? Justify your answer.

A Classify each example as a physical change or a chemical change. \begin{equation} \begin{array}{l}{\text { a. crushing an aluminum can }} \\ {\text { b. recycling used aluminum cans to make new aluminum cans }} \\ {\text { c. aluminum combining with oxygen to form aluminum oxide }}\end{array} \end{equation}

Describe the results of a physical change and list three examples of physical change.

Describe the results of a chemical change. List four indicators of chemical change.

Calculate Solve each of the following. \begin{equation} \begin{array}{l}{\text { a. In the complete reaction of } 22.99 \mathrm{g} \text { of sodium with } 35.45 \mathrm{g} \text { of chlorine, what }} \\\ {\text { mass of sodium chloride is formed? }}\end{array} \end{equation} \begin{equation} \begin{array}{l}{\text { b. } A 12.2 \text { -g sample of } X \text { reacts with a sample of } Y \text { to form } 78.9 \text { g of } X Y . \text { What }} \\ {\text { is the mass of } Y \text { that reacted? }}\end{array} \end{equation}

Evaluate A friend tells you, "Because composition does not change during a physical change, the appearance of a substance does not change." Is your friend correct? Explain.

A Classify each of the following as either a heterogeneous or a homogeneous mixture. a. tap water \(\quad\) b. air \(\quad\) c. raisin muffin

Describe the separation technique that could be used to separate each of the following mixture. \begin{equation} \begin{array}{l}{\text { a. two colorless liquids }} \\ {\text { b. a nondissolving solid mixed with a liquid }} \\ {\text { c. red and blue marbles of the same size and mass }}\end{array} \end{equation}

Design a concept map that summarizes the relationships among matter, elements, mixtures, compounds, pure substances, homogeneous mixtures, and heterogeneous mixtures.

A 78.0 -g sample of an unknown compound contains 12.4 g of hydrogen. What is the percent by mass of hydrogen in the compound?

1.0 \(\mathrm{g}\) of hydrogen reacts completely with 19.0 \(\mathrm{g}\) of fluorine. What is the percent by mass of hydrogen in the compound that is formed?

If 3.5 \(\mathrm{g}\) of element \(\mathrm{X}\) reacts with 10.5 \(\mathrm{g}\) of element \(\mathrm{Y}\) to form the compound \(\mathrm{XY},\) what is the percent by mass of element \(\mathrm{X}\) in the compound? The percent by mass of element \(\mathrm{Y}\) ?

Two unknown compounds are tested. Compound I contains 15.0 \(\mathrm{g}\) of hydrogen and 120.0 g of oxygen. Compound II contains 2.0 \(\mathrm{g}\) of hydrogen and 32.0 \(\mathrm{g}\) of oxygen. Are the compounds the same? Explain your answer.

Challenge All you know about two unknown compounds is that they have the same percent by mass of carbon. With only this information, can you be sure the two compounds are the same? Explain.

Compare and contrast elements and compounds.

Describe the basic organizational feature of the periodic table of the elements.

Explain how the law of definite proportions applies to compounds.

State the type of compounds that are compared in the law of multiple proportions.

Calculate the mass percent of hydrogen in water and the mass percent of oxygen in water.

List three examples of substances. Explain why each is a substance.

Is carbon dioxide gas a pure substance? Explain.

List at least three physical properties of water.

Identify each physical property as extensive or intensive. \begin{equation} \begin{array}{ll}{\text { a. melting point }} & {\text { c. density }} \\\ {\text { b. mass }} & {\text { d. length }}\end{array} \end{equation}

List the three states of matter, and give an example for each state. Differentiate between a gas and a vapor.

Classify each as either a solid, a liquid, or a gas at room temperature. \begin{equation} \begin{array}{ll}{\text { a. milk }} & {\text { d. helium }} \\ {\text { b. air }} & {\text { e. diamond }} \\ {\text { c. copper }} & {\text { f. candle wax }}\end{array} \end{equation}

Classify each as a physical property or a chemical property. \begin{equation} \begin{array}{l}{\text { a. Aluminum has a silvery color. }} \\ {\text { b. Gold has a density of 19 } \mathrm{g} / \mathrm{cm}^{3} \text { . }} \\\ {\text { c. Sodium ignites when dropped in water. }}\end{array} \end{equation} \begin{equation} \begin{array}{l}{\text { d. Water boils at } 100^{\circ} \mathrm{C} \text { . }} \\ {\text { e. Silver tarnishes. }} \\ {\text { f. Mercury is a liquid at room temperature. }}\end{array} \end{equation}

A carton of milk is poured into a bowl. Describe the changes that occur in the milks shape and volume.

Boiling Water At what temperature would 250 \(\mathrm{mL}\) of water boil? 1000 \(\mathrm{mL}\) ? Is the boiling point an intensive or extensive property? Explain.

Classify each as a physical change or a chemical change. \begin{equation} \begin{array}{l}{\text { a. breaking a pencil in two }} \\ {\text { b. water freezing and forming ice }} \\ {\text { c. frying an egg }} \\ {\text { d. burning wood }} \\ {\text { e. leaves changing colors in the fall }}\end{array} \end{equation}

Ripening Is the process of bananas ripening a chemical change or a physical change? Explain.

Is a change in phase a physical change or a chemical change? Explain.

List four indicators that a chemical change has probably occured.

Rust Iron and oxygen combine to form iron oxide, or rust. List the reactants and products of this reaction.

Burning Candle After burning for three hours, a candle has lost half of its mass. Explain why this example does not violate the law of conservation of mass.

Describe the difference between a physical change and a chemical change.

Ammonia Production \(\mathrm{A} 28.0\) -g sample of nitrogen gas combines completely with 6.0 \(\mathrm{g}\) of hydrogen gas to form ammonia. What is the mass of ammonia formed?

A 13.0 -g sample of X combines with a \(34.0-\mathrm{g}\) sample of \(\mathrm{Y}\) to form the compound \(\mathrm{XY}_{2} .\) What is the mass of the reactants?

If 45.98 \(\mathrm{g}\) of sodium combines with an excess of chlorine gas to form 116.89 \(\mathrm{g}\) of sodium chloride, what mass of chlorine gas is used in the reaction?

A substance breaks down into its component elements when it is heated. If 68.0 g of the substance is present before it is heated, what is the combined mass of the component elements after heating?

Copper sulfide is formed when copper and sulfur are heated together. In this reaction, 127 \(\mathrm{g}\) of copper reacts with 41 \(\mathrm{g}\) of sulfur. After the reaction is complete, 9 \(\mathrm{g}\) of sulfur remains unreacted. What is the mass of copper sulfide formed?

When burning 180 of glucose in the presence of 192 of oxygen, water and carbon dioxide are produced. If 108 gof water is produced, how much carbon dioxide is produced?

Describe the characteristics of a mixture.

Describe a method that could be used to separate each mixture. \begin{equation} \begin{array}{ll}{\text { a. iron filings and sand }} & {\text { c. the components of ink }} \\ {\text { b. sand and salt }} & {\text { d. helium and oxygen gases }}\end{array} \end{equation}

"A mixture is the chemical bonding of two or more sub- stances in any proportion." Is this statement true or false? Explain.

Which of the following are the same and which are different? \begin{equation} \begin{array}{l}{\text { a. a substance and a pure substance }} \\ {\text { b. a heterogeneous mixture and a solution }} \\ {\text { c. a substance and a mixture }} \\ {\text { d. a homogeneous mixture and a solution }}\end{array} \end{equation}

Describe how a homogeneous mixture differs from a heterogeneous mixture.