Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Chemical potential wikipedia , lookup
Artificial photosynthesis wikipedia , lookup
Gas chromatography wikipedia , lookup
Water pollution wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Atomic theory wikipedia , lookup
Electrolysis of water wikipedia , lookup
Freshwater environmental quality parameters wikipedia , lookup
History of chemistry wikipedia , lookup
Safety data sheet wikipedia , lookup
Chemical thermodynamics wikipedia , lookup
AP Chemistry - Problem Drill 03: Matter and Energy Question No. 1 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 1. Which of the following is a pure substance? Question (A) (B) (C) (D) (E) Air Brass Tap water Carbon Dioxide Salt Water A. Incorrect! Air appears to be the same throughout…but air contains various atoms, molecules, and particles Gases such as oxygen, carbon dioxide and hydrogen, as well as fine particles are all included in “air.” Air is a homogeneous mixture, not a pure substance. B. Incorrect! Brass appears uniform. This may be a difficult decision for you if you are not aware of the components of brass. It is a mixture of copper and zinc. Since it is a mixture of more than one element that is chemically bonded, it is therefore a homogeneous mixture and not a pure substance. Feedback C. Incorrect! Tap water appears to be the same throughout. However, there are many components in tap water (fluoride for teeth, chlorine to kill bacteria, rust from pipes, etc.) Therefore, tap water is a homogeneous mixture and not a pure substance. D. Correct! Carbon dioxide is a chemical compound—one carbon and two oxygen atoms are bonded together. Therefore, it is a pure substance. E. Incorrect! Salt water looks the same throughout. However, it is composed of salt dissolved in water. Therefore there is more than one type of matter present. It is a homogeneous mixture which means it is not a pure substance. Carbon dioxide is a chemical compound—one carbon and two oxygen atoms are bonded together. Therefore, it is a pure substance. The rest of the options look like pure substances but are all homogeneous mixtures. The correct answer is (D). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 2 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 2. Which of the following is a heterogeneous mixture? Question (A) (B) (C) (D) (E) Table salt Pop Air Steel Brass A. Incorrect! Table salt (NaCl, sodium chloride) is two elements chemically bonded together. Therefore it is a compound. Compounds are pure substances and therefore it is not a heterogeneous mixture. B. Correct! Pop is a mixture of sugars, flavors, water, caffeine, carbon dioxide, etc. The carbon dioxide is in gaseous form, causing bubbles. Since the mixture has a liquid portion and a gaseous portion (the bubbles), it is a heterogeneous mixture. C. Incorrect! Air is a mixture of various gases (oxygen, hydrogen, carbon dioxide, etc.) and small air particles. These various types of matter are not visible. Therefore, air is a homogeneous mixture…not a heterogeneous one. Feedback D. Incorrect! Steel is a mixture of carbon and iron. However, the two types of elements are not visible in the finished product. Therefore it is a homogeneous mixture, not a heterogeneous one. E. Incorrect! Brass is a mixture of copper and zinc. However, the two types of elements are not visible in the finished product. Therefore it is a homogeneous mixture, not a heterogeneous one. The carbon dioxide is in gaseous form, causing bubbles. Since pop has a liquid portion and a gaseous portion (the bubbles), it is a heterogeneous mixture. All of the other options are homogeneous mixtures—they are composed of more than one thing but they look like one thing. The correct answer is (B). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 3 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 3. Which of the following is not a common sign of a chemical change? Question (A) (B) (C) (D) (E) Bubbles Light given off Solution getting warm Precipitate forming A solid melting A. Incorrect! Bubbles indicate that a gas is being formed. This is a common indicator of a chemical change. (However, it can accompany physical changes as well, such as during boiling or pressure changes with a solution containing a dissolved gas). B. Incorrect! Light being given off is a common indicator of a chemical change. C. Incorrect! An energy (temperature) change is a common indicator of chemical changes. (Although energy changes can accompany physical changes as well, such as phase changes or dissolving). Feedback D. Incorrect! A precipitate is an insoluble compound that forms after combining two solutions (made for soluble compounds). Therefore, a new substance is made (one that is insoluble). This is a chemical change. E. Correct! Melting is a physical change from a “solid phase” to a “liquid phase”. Therefore, a solid melting is not a sign of a chemical change. Although there are signs that can signify a chemical change—you must be careful. Some of these signs can also be present in a physical change. To determine for sure, you could test various properties of the final sample and compare them to the original sample. If the sample now has many different properties or components then it was a chemical change. The correct answer is (E). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 4 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 4. What type of statement is the following: “The Alkaseltzer will react with the water faster if the tablet is crushed.” Question (A) (B) (C) (D) (E) Prediction Law Hypothesis Theory Idea A. Correct! A prediction does not attempt to explain why—it simply predicts what will happen. This statement is a prediction. B. Incorrect! A law describes natural phenomena which can occasionally be approximated by a mathematical expression. C. Incorrect! A hypothesis includes a prediction and an attempt to explain why. This statement is just a prediction. Feedback D. Incorrect! A theory attempts to explain why phenomenon occurs the way that it does. E. Incorrect! Although this statement may be considered an idea, in science we refer to it as a prediction. Theories and hypothesis attempt to explain why phenomenon occurs the way that it does. This statement does not include any form of explanation. A law describes natural phenomena, usually with math. This statement is a prediction. The correct answer is (A). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 5 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 5. Which of the following is a valid reason for why making Kool-ade is a physical change? Question (A) A color change is seen. (B) The dry ingredients that are added to the water can be acquired again by evaporating the water. (C) It makes a homogeneous mixture. (D) There is no temperature change. (E) The dry ingredients disappear. A. Incorrect! A color change is a common sign of a chemical change; therefore it does not prove that this is a physical change. B. Correct! Evaporating water is a physical change. If a physical change can un-do a previous change, then the previous change must have been physical as well. Therefore, this is a valid argument for this change being physical. C. Incorrect! Many chemical processes also make homogeneous mixtures; therefore this is not proof that this change is physical. Feedback D. Incorrect! Although temperature changes are often common in chemical changes, not all chemical changes result in a temperature change. Therefore, the lack of a significant temperature change is not proof that the change is physical. E. Incorrect! The dry ingredients do not disappear; they spread out when they are dissolved until the naked eye cannot detect them. Color changes and temperature changes are often signs of chemical changes, but they are not proof one way or another. Evaporating water is a physical change. If a physical change can un-do a previous change, then the previous change must have been physical as well. Therefore, this is a valid argument for this change being physical. The correct answer is (B). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 6 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 6. Which of the following is not a physical change? Question (A) (B) (C) (D) (E) Melting Drying Evaporating Burning Boiling A. Incorrect! Melting is a physical change from solid to liquid. B. Incorrect! Drying, boiling and evaporating are all physical changes from liquid to gas. C. Incorrect! Drying, boiling and evaporating are all physical changes from liquid to gas. Feedback D. Correct! Burning is a chemical change (combustion). E. Incorrect! Drying, boiling and evaporating are all physical changes from liquid to gas. Melting is a physical change from solid to liquid. Drying, boiling and evaporating are all physical changes from liquid to gas. Burning is a chemical change. The correct answer is (D). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 7 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 7. Which of the following is a mixture? Question (A) (B) (C) (D) (E) Ice and water Aluminum oxide Table salt (sodium chloride) Liquid mercury Gold foil A. Correct! Even though ice and water are both H2O, it is considered a mixture because there is more than one “state” together. B. Incorrect! Aluminum and oxygen bonded together form aluminum oxide. It is a compound and compounds are not mixtures. C. Incorrect! Sodium chloride is sodium and chloride bonded together. It is a compound and compounds are not mixtures. Feedback D. Incorrect! Liquid mercury is an element. Elements are not mixtures. E. Incorrect! Gold foil contains only gold atoms. Elements are not mixtures. Aluminum oxide and sodium chloride are compounds, which are not mixtures. Mercury and gold are elements, which are not mixtures. Ice and water, although both H2O, are different states of matter and therefore are a mixture when together. The correct answer is (A). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 8 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 8. Which of the following is a pure substance? Question (A) (B) (C) (D) (E) Tap water Granite Air Deoxyribonucleic acid (DNA) Wood A. Incorrect! Tap water often looks pure, however it has many dissolved substances, such as chlorine and fluoride. Therefore it is a mixture. B. Incorrect! Granite has different flakes and chunks of various colors and rock. Therefore it is a heterogeneous mixture, and not a pure substance. C. Incorrect! Air looks pure, however it is a mixture of oxygen, hydrogen, carbon dioxide, that are not chemically bonded together. Feedback D. Correct! DNA is a molecule—it is a pure substance. E. Incorrect! Wood is a heterogeneous mixture of many types of molecules. Tap water and air may look like a pure substance, but they are homogeneous mixtures. Wood and granite are heterogeneous mixtures. DNA is a molecule and is therefore a pure substance. The correct answer is (D). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 9 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 9. Which type of matter can be separated chemically but not physically? Question (A) (B) (C) (D) (E) Elements Compounds Heterogeneous mixtures Homogeneous mixtures Solutions A. Incorrect! Elements cannot be separated physically or chemically. B. Correct! Compounds can be separated chemically but not physically. C. Incorrect! All types of heterogenous mixtures can be separated physically. Feedback D. Incorrect! All types of homogenous mixtures can be separated physically. E. Incorrect! All types of solutions can be separated physically, for instance, the distillation of alcohol. Elements cannot be separated chemically or physically. All types of mixtures can be separated physically. Compounds can be separated chemically but not physically. The correct answer is (B). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved Question No. 10 of 10 Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed. 10. Which of the following is a physical change? Question (A) (B) (C) (D) (E) Burning Oxidizing Rusting Boiling Decomposing A. Incorrect! Burning is a chemical change. B. Incorrect! Oxidizing is a chemical change. C. Incorrect! Rusting is the oxidizing of iron, which is a chemical change. Feedback D. Correct! Boiling is the physical change from a “liquid phase” to a “gas phase”. E. Incorrect! Decomposing is the chemical breaking down of a substance. Burning, oxidizing, rusting and decomposing are chemical processes while boiling is a physical change from liquid to gas. The correct answer is (D). Solution RapidLearningCenter.com © Rapid Learning Inc. All Rights Reserved