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Chemistry - Chapter 1 Questions
Terms in this set (57)
Explain why the study of chemistry should be important to everyone. (1.1)
Chemistry is the study of matter and everything and everyone is made of matter.
Define substance and give two examples of things that are substances. (1.1)
A substance, which is also known as a chemical, is matter that has a definite composition. Possible examples: table salt and table sugar
Describe how the ozone layer forms and why it is important. (1.1)
When oxygen gas (0²) is exposed to ultraviolet radiation in the upper regions of the stratosphere, the molecule breaks apart. The individual oxygen particles (O) combine with other oxygen gas molecules to form ozone (O³). Ozone is important because it forms a protective layer in the atmosphere that protects living organisms from harmful radiation.
Explain why chlorofluorocarbons were developed and how they are used. (1.1)
Chlorofluorocarbons were developed as a safe alternative to ammonia, a common refrigerant. Chlorofluorocarbons are used as refrigerants, in foams, and as propellants in spray cans.
Explain If cells have the ability to repair themselves after exposure to UVB, why are the increasing levels of UVB in the atmosphere concerning scientists? (1.1)
Cells have some ability to repair themselves, but some scientists believe that cells have a limit in the amount of UVB exposure that can be tolerated.
Explain why the concentration of CFCs increased in the atmosphere. (1.1)
The use of CFCs continued to increase.
Evaluate why it was important for Dobson's data to be confirmed by satellite photos. (1.1)
All scientific hypotheses, tests, experiments, and data must be independently confirmed to make them valid.
Explain why there are different branches of chemistry. (1.2)
The study of chemistry is a very broad field, so chemists specialize in small areas.
Explain why scientists use mass instead of weight for their measurements. (1.2)
Mass is constant regardless of location and is not affected by gravity. Weight varies with gravity.
Why is it important for chemists to study changes in the world at a submicroscopic level. (1.2)
The changes you see with your eyes begin with changes at the submicroscopic level.
Why do chemists use models to study submicroscopic matter. (1.2)
Models enable chemists to understand difficult concepts that they cannot normally see.
Identify three different models that scientists use and explain why each model is useful. (1.2)
Possible answers: Aircraft models allow scientists to test their designs before money is spent on the actual aircraft. Computer models of chemical processes allow chemists to test processes before actual manufacturing facilities are built. Car models allow scientists to test certain features, such as wind resistance, before a car is actually built.
How would your mass and weight differ on the moon? The gravitational force of the moon is one-sixth the gravitational force on Earth. (1.2)
Your mass would be the same, but your weight would be 1/6 your weight on Earth.
If you put a scale in an elevator and weigh yourself as you ascend and then descend, does the scale have the same reading in both instances? Explain your answer.
As the elevator moves up and down at constant velocity, the reading on the scale will be the same as it is when the elevator is stationary. However, during the time the elevator accelerates upward, the scale reading will be higher, during the time when the elevator accelerates downward, the scale reading will be lower.
Explain why scientists do not use a standard set of steps for every investigation they conduct.
The nature of investigations varies a great deal and the steps needed to perform a wide array of investigations must also vary.
Give an example of quantitative and qualitative data.
Possible answers: qualitative, silver-colored liquid; quantitative, 5 mL
You are asked to study the effect of temperature on the volume of a balloon. The balloon's size increases as it is warmed. What is the independent variable? The dependent variable? What factor is held constant? How would you construct a control?
Independent variable, the temperature; dependent variable, the size of the balloon; factor held constant, the amount of air in the balloon; control, an identical balloon kept at the original temperature
Jacques Charles described the direct relationship between temperature and volume of all gases at constant pressure. Should this be called Charles's law or Charles's theory? Explain.
It is called Charles's law because it describes a phenomenon that consistently takes place.
Good scientific models can be tested and used to make predictions. What did Molina and Rowland's model of the interactions of CFCs and ozone in the atmosphere predict would happen to the amount of ozone in the stratosphere as the level of CFCs increased?
Their models predicted that as CFC concentrations increased, ozone levels would decrease.
Name three technological products that have improved our lives or the world around us.
Possible answers: computer, internal combustion engine, and vaccinations.
Compare and contrast pure research and applied research.
Pure research is done for the sake of knowledge. Applied research is done to solve a specific problem.
Is technology a product of pure research or applied research? Explain.
Technology can be the product of either one. It can be a product of pure research when scientists realize their discovery has a practical application. It can also be a product of applied research when scientists perform research to solve a particular problem.
Wear goggles and an apron in the lab even if you are only an observer. Why?
Harmful substances can get in your eyes and on your clothing if you are performing an experiment or just watching it being performed.
Do not return unused chemicals to the stock bottle. Why?
The chemicals might be contaminated and you do not want to contaminate the stock bottle.
Do not wear contact lenses in the laboratory. Why?
Contact lenses can absorb gases that can damage your eyes and they are difficult to remove during an emergency situation.
Avoid wearing loose, draping clothing and dangling jewelry. Why?
It is easy to drag these items through chemicals and across flames, which might create a hazardous situation.
Interpret Scientific Diagrams What safety precautions should you take when the following safety symbols are listed?
It is easy to drag these items through chemicals and across flames, which might create a hazardous situation.
Define substance and chemistry.
Substance—any sample with a definite composition; chemistry—the study of matter and the changes it undergoes
Where is ozone located in Earth's atmosphere?
90% in the stratosphere
What three elements are found in chlorofluorocarbons?
Carbon, fluorine, and chlorine
What were common uses of CFCs?
Refrigerants, foams, propellants for spray products
Scientists noticed that the ozone layer was thinning. What was occurring at the same time?
Increased usage of CFCs
Why do chemists study regions of the universe?
Because chemists study matter and matter is found throughout the universe.
If three oxygen particles are needed to form ozone, how many units of ozone could be formed from 6 oxygen particles? From 9? From 27?
2 units; 3 units; 9 units
Measuring Concentration The CFC level was measured at about 272 ppt (parts per thousand) in 1995. Since percent means parts per hundred, what percent is represented by 272 ppt?
Why is chemistry called the central science?
An understanding of chemistry is central to all sciences and to our everyday lives.
Which measurement depends on gravitational force—mass or weight? Explain.
Weight; weight is calculated using the acceleration due to gravity; mass is independent of gravity
Which branch of chemistry studies the composition of substances? The environmental impact of chemicals?
Analytical chemistry studies the composition of substances; environmental chemistry studies the environmental impact of chemicals.
Predict whether your weight in the city of Denver, which has an altitude of 1.7 km above sea level, will be the same as, more than, or less than your weight in New Orleans, a city located at sea level.
Your weight would be less in Denver because the acceleration due to gravity is less in Denver than in New Orleans.
The text tells you "1 trillion atoms could fit onto a period at the end of this sentence." Write out the number 1 trillion using the correct number of zeroes.
How much mass will a 4 cm³ cube have if a 2-cm³ cube of matter has a mass of 4.0 g?
4.0g / 2 cm³ = x / (4 cm³); x = 128 g
How does qualitative data differ from quantitative data? Give an example of each.
Qualitative data, such as color or shape, are made with the five senses. Quantitative data, such as mass or length, are measurements.
What is the function of a control in an experiment?
A control is a standard used for comparison.
What is the difference between a hypothesis, a theory, and a law?
A hypothesis is a tentative explanation about what has been observed. A theory is an explanation that has been supported by many experiments. A scientific law describes a relationship in nature.
You are asked to study how much table sugar can be mixed or dissolved in water at different temperatures. The amount of sugar that can dissolve in water goes up as the water's temperature goes up. What is the independent variable? Dependent variable? What factor is held constant?
Temperature; amount of sugar dissolved; amount of water
Label the data as qualitative or quantitative: a beaker weighs 6.6 g
Label the data as qualitative or quantitative: sugar crystals are white and shiny
Label the data as qualitative or quantitative: fireworks are colorful
If evidence you collect during an experiment does not support your hypothesis, what should happen to that hypothesis?
The hypothesis should be rewritten based on the new information and the new hypothesis should be tested.
One carbon (C) and one ozone (O³) react to form one carbon monoxide (CO) and one oxygen gas (O²) particle. How many ozone particles are needed to form 24 particles of oxygen gas (O²)?
1 particle O³ / 1 particle O² = x particles O³ / 24 particles O²
Finish the statement: Study your lab assignment.
Before you come to the lab
Finish the statement: Keep food, beverages, and chewing gum
Out of the lab
Finish the statement: Know where to find and how to use the
Fire extinguisher, safety shower, fire blanket, and first-aid kit
If your lab procedure instructs you to add two parts acid to each one part of water and you start with 25 mL of water, how much acid will you add and how will you add it?
2 x 25 mL = 50 mL acid; Always add acid to the water very slowly.
Match each of the following research topics with the branch of chemistry that would study it: water pollution, the digestion of food in the human body, the composition of a new textile fiber, metals to make new coins, and a treatment for AIDS.
Possible answers: water pollution, environmental chemistry; the digestion of food, biochemistry; textile fibers, polymer chemistry; metal coins, inorganic chemistry; AIDS treatment, biochemistry.
CFCs break down to form chemicals that react with ozone. Is this a macroscopic or a microscopic observation?
A newscaster reports, "The air quality today is poor. Visibility is only 1.7 km. Pollutants in the air are expected to rise above 0.085 parts per million (ppm) in the next eight-hour average. Spend as little time outside today as possible if you suffer from asthma or other breathing problems." Which of these statements are qualitative and which are quantitative?
The qualitative statements are that air quality is poor and that people should spend little time outside. Quantitative statements include that visibility is only 1.7 km and that the pollutants will rise above 0.085 ppm in the next eight-hour average.
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