Chapter 1

After the exam has been completed, you have the students anonymously fill out a questionnaire asking about their study habits for the exam and the grade they earned on the exam. From the surveys, you randomly select 10 students who studied for the exam and 10 students who did not study for the exam. You create the table showing the students' exam grades given here: Grades of 10 students who studied Exam grade 93, 96, 89, 88, 88, 100, 77, 96, 98, 85 Grades of 10 students who did not study Exam grade 65, 73, 71, 64, 56, 49, 89, 66, 76, 61 What was the average exam grade for each set of students?

91, 67

According to the scientific method, what is a law?

A brief statement that summarizes past observations and predicts future ones.

Which statement most resembles a scientific theory?

A gas is composed of small particles in constant motion.

Which statement is an example of an observation?

Cardboard covered with tetracyanoplatinate(II) barium glows in the dark room when it is close to a cathode-ray tube.

What are chemicals?

Chemicals are what make up everything around us, including ourselves.

What is the law of conservation of mass?

In a chemical reaction, matter is neither created nor destroyed.

Matter is conserved in chemical reactions.

Law

When a metal is burned in a closed container, the mass of the container and its contents do not change.

Observation

When wood is burned in a closed container, its mass does not change.

Observation

A chemist in an imaginary universe does an experiment that attempts to correlate the size of an atom with its chemical reactivity. The results are tabulated as follows. (b)Formulate a theory to explain the law.

Reactivity is due to the momentum of collisions, and because the larger particles have a greater momentum, they have a greater reactivity.

Give some examples of pure chemical substances.

Sugar, carbon dioxide and water.

Part complete A student prepares several samples of the same gas and measures their mass and volume. The results are tabulated as follows: Formulate a tentative law from the measurements

The mass-to- volume ratio of a gas is constant, The mass of a gas is directly proportional to its volume.

A chemist in an imaginary universe does an experiment that attempts to correlate the size of an atom with its chemical reactivity. The results are tabulated as follows. (a) Formulate a law from these data.

The reactivity of a chemical is proportional to the atomic size.

Matter is made of atoms.

Theory

An example of a theory is modern atomic theory, which states that all matter is composed of small particles called atoms. Based on what you know about scientific theories in general, classify the following statements regarding modern atomic theory as true or false.

True: It is currently accepted as the most plausible explanation for the law of conservation of mass, It is supported by data, It is subject to experimentation and revision. False: It proves the existence of atoms, It is mere speculation, It is the only possible explanation for the law of conservation of mass.

An example of a scientific law is the law of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction. Based on what you know about scientific laws in general, classify the following statements regarding the law of conservation of mass as true or false.

True: It was developed from past observations, It is subject to experimentation and revision, It predicts future observations. False: It explains why mass is conserved

Which of the following is the smallest particle of matter?

an atom of oxygen

Before we begin, let's first establish an understanding of basic terminology. It may be harder than you think to clearly define what is a chemical versus a chemical reaction. To help us better differentiate between closely related terms, review the words listed here. Sort each of the words into the three categories: contains chemicals, chemical reaction, or neither.

contains chemicals: vitamin b1, protein, granite, oranges chemical reaction: photosynthesis, neutralization, combustion, rusting neither: sunlight, rainbow, heat

You call one of your friends to go to a movie on Friday night. He declines your invitation, stating that he needs to study for his upcoming exam on Monday. He states that he scores higher on a exam when he studies for the exam. Despite your efforts to convince him to go to the movie, he stays at home to study for his exam. You decide to use the scientific method to test the hypothesis that students who study for an exam tend to score higher than students who do not study for an exam. In what order should you conduct the following steps to test your hypothesis?

design an experiment, collect data, analyze data, confirm or revise hypothesis

Chemists attempt to understand how ____ behaves, by studying the properties of ____.

matter, atoms and molecules

What is the atomic theory? Who formulated it?

All matter is composed of small, indestructible particles called atoms; John Dalton.

Which of the following statements is correct?

All matter is composed of tiny particles called atoms.

Who discovered the law of conservation of mass?

Antoine-Laurent Lavoisier

What is the difference between a hypothesis and a theory?

Before a scientific theory is well established, it is referred to as a hypothesis.

The manufacturer of a particular brand of toothpaste claims that the brand contains "no chemicals." (a) What does the company mean by that statement? (b)

(a) The "no chemicals" could refer to additives, preservatives, pesticides, or insecticides, which are all groups of chemicals that many consumers do not want present in their products. Submit, The company is using consumer fear of chemicals to imply that their product is safe. (b) No, because all matter is composed of chemicals.

Read the case study and use your knowledge of the scientific method to identify the observation, hypothesis, experiment, and conclusion. Our English springer spaniels like our neighbors' children and could play with them all day. We thought our dogs will never dislike any children they will ever meet. Last month when we took our dogs on a trip, we met some German tourists in a park. The dogs loved playing with the foreign family's children. Our English springer spaniels like all children.

-Allowing the dogs to play with the German family's children is the experiment. -"Our English springer spaniels like our neighbors' children" is a(n) observation -"Our English springer spaniels like all children" is our conclusion -"Our dogs will never dislike any children they meet" is the hypothesis

Which characteristic is necessary for success in understanding chemistry?

-Inquiring mind -calculation -commitment

How is chemistry connected to everyday life and how is it relevant outside the chemistry laboratory?

-Knowing some chemistry can help you make day-to-day decisions that affect your life -Everything is made of chemicals. -Many of the changes you observe in the world around you are caused by chemical reactions. -Chemistry is not confined to a laboratory.

A student measures the volume of a gas sample at several different temperatures. The results are tabulated as follows: Formulate a tentative law from the measurements.

-The temperature-to-volume ratio of a gas is constant. -The temperature of a gas is directly proportional to its volume.

Choose the correct names of the atoms or molecules.

-ammonia -molybdenum -iron -sulfur trioxide -fluorine

Now that you're talking and thinking more like a chemist, it's useful to understand how you use chemistry every day—not just in the lab, and not just as part of an experiment. Many of the foods you eat and the products you use are made of substances developed by chemists. For the protection of U.S. consumers, the Food and Drug Administration (FDA) closely regulates product labels, requiring manufacturers to list all of the ingredients in a product. On food labels, the ingredients are listed in order of quantity, so you know that there is more of the first ingredient than any other ingredient. For product labels, the quantity of each ingredient may be less important than the actual effect of the ingredient. Therefore, active ingredients are often separated from the inactive ingredients. Review the label from a common brand of mouthwash and answer the questions.

1. Sodium fluoride is the highest concentration active ingredient 2. According to the label, its purpose in the mouthwash is to fight plaque and gingivitis. 3. Water is the highest concentration inactive ingredient

The graph below shows the area of a circle as a function of its radius. What is the radius of a circle that has an area of 113 square inches?

6.0 inches

Which of the following experiment setups would be the best way to test your hypothesis?

After the exam, give students a survey questioning their study habits and what grade they made on their exam.