Matter Preview Understanding Concepts Reading Skills Interpreting Graphics

Understanding Concepts Which of the following is an example of a chemical change? A. gasoline evaporating B. sugar dissolving in water C. a metal surface rusting D. a mixture separating into its components

Understanding Concepts, continued Which of the following is an example of a chemical change? A. gasoline evaporating B. sugar dissolving in water C. a metal surface rusting D. a mixture separating into its components

Understanding Concepts, continued Which of the following terms most accurately describes carbon dioxide? F. element G. compound H. mixture I. solution

Understanding Concepts, continued Which of the following terms most accurately describes carbon dioxide? F. element G. compound H. mixture I. solution

Understanding Concepts, continued An experiment shows that the element mercury has a density of 13.57 g/cm3. What is the volume of 1.000 kg of pure mercury? A. 0.7369 cm3 B. 13.57 cm3 C. 73.69 cm3 D. 1,357 cm3

Understanding Concepts, continued An experiment shows that the element mercury has a density of 13.57 g/cm3. What is the volume of 1.000 kg of pure mercury? A. 0.7369 cm3 B. 13.57 cm3 C. 73.69 cm3 D. 1,357 cm3

Understanding Concepts, continued 4. At 4 °C, the volume of 15 g of water was 15 cm3. At 20 °C, the volume of the same 15 g of water was 15.03 cm3. What effect did the increase in temperature have on the water’s density?

Understanding Concepts, continued At 4 °C, the volume of 15 g of water was 15 cm3. At 20 °C, the volume of the same 15 g of water was 15.03 cm3. What effect did the increase in temperature have on the water’s density? Answer: The density decreased.

Understanding Concepts, continued 5. If the density of water changes because the temperature of the water changes, is this change a physical change or a chemical change?

Understanding Concepts, continued If the density of water changes because the temperature of the water changes, is this change a physical change or a chemical change? Answer: The change in density is a physical change.

Understanding Concepts, continued Study the graph below. Which has a greater density: water or gasoline?

Understanding Concepts, continued Study the graph below. Which has a greater density: water or gasoline? Answer: Water has a greater density than gasoline.

Reading Skills METAL ALLOYS When a metallic element is combined with one or more other elements and the resulting combination has metallic properties, that combination is known as an alloy. Metals are most often alloyed with other metals, but other elements and compounds can also be included in an alloy to give it particular properties. For example, blending small amounts of manganese and carbon with iron creates a substance known as carbon steel. Carbon steel is harder and more corrosion resistant than pure iron. Some alloys are compounds. One example is cementite, Fe3C. Other alloys, such as bronze and brass, are solutions of two or more metals dissolved in one another. Alloys that are mixtures of several compounds may not have a single melting point. Instead, they may have a melting range, in which the material is a combination of a solid and a liquid. EDIT: Check against final.

Reading Skills, continued 7. Which of the following is an alloy? F. iron G. carbon H. bronze I. manganese EDIT: Check against final.

Reading Skills, continued 7. Which of the following is an alloy? F. iron G. carbon H. bronze I. manganese EDIT: Check against final.

Reading Skills, continued 8. An alloy of aluminum is observed to have a melting range instead of a single melting point. What can be concluded from this observation? A. The alloy is a compound. B. The alloy is probably a mixture of different compounds. C. The other components in the alloy have higher melting points. D. Each individual molecule of the aluminum alloy has all of the properties of the alloy. EDIT: Check against final.

Reading Skills, continued 8. An alloy of aluminum is observed to have a melting range instead of a single melting point. What can be concluded from this observation? A. The alloy is a compound. B. The alloy is probably a mixture of different compounds. C. The other components in the alloy have higher melting points. D. Each individual molecule of the aluminum alloy has all of the properties of the alloy. EDIT: Check against final.

Interpreting Graphics The tables below give the chemical formulas for some common substances. Use the tables to answer questions 9–11.

Interpreting Graphics, continued 9. Which of the following substances is classified as a compound? F. water G. ozone H. hydrogen gas I. solid sulfur

Interpreting Graphics, continued 9. Which of the following substances is classified as a compound? F. water G. ozone H. hydrogen gas I. solid sulfur

Interpreting Graphics, continued 10. A mixture contains 100 molecules of table salt, 30 molecules of baking soda, 20 molecules of ethanol, and 10 molecules of water. Atoms from which of the following elements make up most of the mixture? A. sodium, Na C. hydrogen, H B. oxygen, O D. carbon, C

Interpreting Graphics, continued 10. A mixture contains 100 molecules of table salt, 30 molecules of baking soda, 20 molecules of ethanol, and 10 molecules of water. Atoms from which of the following elements make up most of the mixture? A. sodium, Na C. hydrogen, H B. oxygen, O D. carbon, C

Interpreting Graphics, continued 11. A scientist discovers a way to easily combine molecules of ozone and molecules of hydrogen gas to make molecules of water. To create 300 molecules of water, how many molecules of ozone and how many molecules of hydrogen gas would the scientist need?

Interpreting Graphics, continued 11. A scientist discovers a way to easily combine molecules of ozone and molecules of hydrogen gas to make molecules of water. To create 300 molecules of water, how many molecules of ozone and how many molecules of hydrogen gas would the scientist need? Answer: 100 molecules of ozone and 300 molecules of hydrogen gas

Interpreting Graphics, continued A geologist who is studying rocks found on an expedition places a 25 g graduated cylinder on a scale and adds 100 cm3 of water to the cylinder. Then, the geologist places the rocks in the cylinder one at a time, as shown below. Use the graphic to answer questions 12 and 13.

Interpreting Graphics, continued 12. Which rock or rocks have the greatest density?

Interpreting Graphics, continued 12. Which rock or rocks have the greatest density? Answer: Rock B

Interpreting Graphics, continued 13. Which rock or rocks will float to the surface of the water in the cylinder? Why?

Interpreting Graphics, continued 13. Which rock or rocks will float to the surface of the water in the cylinder? Why? Answer: Rock C, because its density is less than water’s.