Unit 1 - Chemistry and Chemicals PDF

Unit 1 - Chemistry and Chemicals In the blood, hemoglobin transports oxygen to the tissues...

Unit 1 - Chemistry and Chemicals In the blood, hemoglobin transports oxygen to the tissues and carbon dioxide to the lungs. Learning Goal Define the term chemistry and identify substances as chemicals. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. What Is Chemistry? Chemistry is the study of composition, structure, properties, and reactions of matter happens all around you every day Antacid tablets undergo a chemical reaction when dropped in water. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. What Is Chemistry? Chemistry is the study of substances in terms of:  Composition What is it made of?  Structure How is it put together?  Properties What characteristics does it have?  Reactions How does it behave with other substances? Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Chemistry Matter is another word for all substances that make up our world. Antacid tablets are matter. Water is matter. The oxygen we breathe is matter. The carbon dioxide we exhale is matter. We are made of matter. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Chemicals Chemicals are substances that have the same composition and properties wherever found often substances made by chemists that you use every day Toothpaste is a combination of many chemicals. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Chemicals Commonly Used in Toothpaste Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Learning Check Which of the following contains chemicals? A. sunlight B. fruit C. milk D. breakfast cereal Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Solution Which of the following contains chemicals? A. Sunlight is energy given off by the Sun and therefore does not contain chemicals. B. Fruit contains chemicals that have the same composition and properties wherever found. C. Milk contains chemicals that have the same composition and properties wherever found. D. Breakfast cereal contains chemicals that have the same composition and properties wherever found. Therefore, only B. Fruit, C. Milk, and D. Breakfast cereal contain chemicals. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. 1.2 Scientific Method Thinking Like a Scientist Linus Pauling won the Nobel Prize in Chemistry in 1954. Learning Goal Describe the activities that are part of the scientific method. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. The Scientific Method The scientific method is a set of general principles that helps to describe how a scientist thinks. 1. Make observations about nature and ask questions about what you observe. 2. Propose a hypothesis, which states a possible explanation of the observations. 3. Several experiments may be done to test the hypothesis. 4. When results of the experiments are analyzed, a conclusion is made as to whether the hypothesis is true or false. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Summary of the Scientific Method The scientific method develops a conclusion or theory using observations, hypotheses, and experiments. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Everyday Scientific Thinking Observation: Yesterday you went to visit your friend. Soon after you arrived, your eyes began to itch and you started to sneeze. You observed that your friend has a new cat. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Everyday Scientific Thinking Hypothesis 1: Perhaps you are allergic to cats. Experiment 1: To test your hypothesis, you leave your friend’s home. If the itching and sneezing stop, perhaps your hypothesis is correct. If the itching and sneezing do not stop, perhaps you have a cold. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Everyday Scientific Thinking Observation: Upon leaving your friend’s home, the itching and sneezing stop. The observation supports your original hypothesis. To confirm, you visit another friend with a cat. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Everyday Scientific Thinking Experiment 2: Visiting a second friend with a cat causes your eyes to itch and you begin to sneeze again, further supporting your hypothesis. Theory: The experimental results indicate that indeed you are allergic to cats. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Learning Check Identify each of the following as an observation, a hypothesis, an experiment, or a conclusion: A. During your visit to the gym, your trainer records that you ran for 25 min on the treadmill. B. Scientific studies show that exercising lowers blood pressure. C. Your doctor thinks that your weight loss is due to increased exercise. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Solution Identify each of the following as an observation, a hypothesis, an experiment, or a conclusion: A. During your visit to the gym, your trainer records that you ran for 25 min on the treadmill. Observation B. Scientific studies show that exercising lowers blood pressure. Conclusion C. Your doctor thinks that your weight loss is due to increased exercise. Hypothesis Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Learning Check For each of the following, indicate whether the step of the scientific method being described is (1) observation, (2) hypothesis, (3) experiment, or (4) theory. A. A blender does not work when plugged in. B. The blender motor is broken. C. The plug has malfunctioned. D. The blender does not work when plugged into a different outlet. E. The blender needs repair. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Solution For each of the following, indicate whether the step of the scientific method being described is (1) observation, (2) hypothesis, (3) experiment, or (4) theory. A. A blender does not work when plugged in. (1) B. The blender motor is broken. (2) C. The plug has malfunctioned. (2) D. The blender does not work when plugged into a (3) different outlet. E. The blender needs repair. (4) Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. 1.3 Studying and Learning Chemistry Studying in a group can be beneficial to learning. Learning Goal Identify strategies that are effective for learning. Develop a study plan for learning chemistry. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Strategies to Improve Learning and Understanding Success in chemistry utilizes good study habits, connecting new information with your knowledge base, rechecking what you have learned and what you have forgotten, and retrieving what you have learned for an exam. Here are some tips for developing new study habits: Do not keep rereading the text or notes. Ask yourself questions as you read. Self-test by giving yourself quizzes using practice problems in the text. Study at a regular pace rather than cramming. Study different topics in a chapter and relate the new concepts to concepts you know. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  1.4 Key Math Skills for Chemistry Learning Goal Review math concepts used in chemistry: place values, positive and negative numbers, percentages, solving equations, and interpreting graphs. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Identifying Place Values For any number, we can identify a place value for each digit. 2518 g Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Identifying Place Values We can identify a place value for each digit in a number with a decimal point. 6.407 g Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Learning Check Identify the place value for each of the digits in the following number: 15.24 g Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Solution Identify the place value for each of the digits in the following number: 15.24 g Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Positive and Negative Numbers A positive number is any number that is greater than zero and has a positive sign (+). Often the positive sign is understood and not written in front of the number. For example: +8 is also written as 8. A negative number is any number that is less than zero and is written with a negative sign (−). For example: −8. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Multiplication with (+) and (–) Numbers When two positive numbers or two negative numbers are multiplied, the answer is positive. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Multiplication with (+) and (–) Numbers When a positive number and a negative number are multiplied, the answer is negative. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Division with (+) and (–) Numbers The rules for division of positive and negative numbers are the same as those for multiplication. When two positive numbers or two negative numbers are divided, the answer is positive (+). Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Division with (+) and (–) Numbers When a positive number and a negative number are divided, the answer is negative (−). Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Addition with (+) and (–) Numbers When positive numbers are added, the sign of the answer is positive (+). 3+4=7 The (+) sign (+7) is understood. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Addition with (+) and (–) Numbers When negative numbers are added, the sign of the answer is negative (−). (−3) + (−4) = −7 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Addition with (+) and (–) Numbers When a positive number and a negative number are added, the smaller number is subtracted from the larger number. The result has the same sign as the larger number. 12 + (−15) = −3 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Subtraction with (+) and (–) Numbers When two numbers are subtracted, change the sign of the number to be subtracted. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Calculator Operations On your calculator, there are four keys used for basic mathematical operations. The change sign key is used to change the sign of a number. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Calculator Operations—Example Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd. Calculating a Percentage To determine a percent, divide the parts by the total (whole) and multiply by 100%. An aspirin tablet contains 325 mg of aspirin (active ingredient), and the tablet has a mass of 545 mg. What is the percentage of aspirin in the tablet? Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Percentage A percentage (%) represents the number of parts of an item in 100 of those items. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Solving Equations Equations can be rearranged to solve for an unknown variable. 2x + 8 = 14 1. Place all like items on one side. Subtract 8 from each side: 2x + 8 − 8 = 14 − 8 2x =6 2. Isolate the variable you need to solve for. Divide both sides by 2: 3. Check your answer. 2(3) + 8 = 14 6 + 8 = 14 14 = 14 Your answer x = 3 is correct Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Learning Check Solve the following equation for P1: 1 1 = P2V2 PV Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Solution Solve the following equation for P1: 1 1 = P2V2 PV To solve for P1, divide both sides by V1. PV P2V2 P2V2 1 1 =  P1 = V1 V1 V1 Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Graphs A graph represents the relationship between two variables. The graph below represents the volume of a gas plotted against its temperature. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Interpreting a Graph The graph title, “Volume of a Balloon versus Temperature,” indicates that the volume of a gas is plotted against its temperature. The vertical (y) axis label indicates that the volume is measured in liters. The horizontal (x) axis label indicates that the temperature of the balloon is measured in degrees Celsius. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.  Interpreting a Graph Each point on the graph represents a volume in liters that was measured at a specific temperature. The line on the graph indicates that the volume of the balloon increases as the temperature of the gas increases. This is called a direct relationship. Chemistry: An Introduction to General, Organic, and Biological Chemistry, Thirteenth Edition, Global Edition © 2019 Pearson Education Ltd.