Matter: Properties and Changes

Transcription

1 Matter: Properties and Changes Properties of Matter A pure substance is matter that has and composition. Examples: and A physical property is a characteristic that can be or without changing the sample s. Examples:,,,, Physical properties can fall under two categories: extensive properties or intensive properties. Extensive properties are dependent upon. Examples:,,, Intensive properties are dependent upon. Example:,,,, A chemical property is Examples:,, States of Matter: List the properties for each state of matter. Solids 1

2 Liquids Gases Changes in Matter A physical change is a type of change that alter the properties of a substance but does not change its. Examples: 2

3 A chemical change is a process involving one or more substances changing into. This process is also called a. Evidence of a Chemical Change (make list) Conservation of Mass Mass is neither nor in a chemical reaction it is. Mass products = Mass reactants Example g of red mercury (II) oxide powder is placed in an open flask and heated until it is converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of oxygen formed by the reaction? Mixtures of Matter A mixture is a. A heterogeneous mixture is one that does not and the individual substances remain. Examples:, A homogeneous mixture has throughout. These mixtures are also referred to as. Examples:, 3

4 Separating Mixtures Filtration is a technique that uses a to separate a from a. Distillation is a technique that is used to separate mixtures based on differences in the of the substances involved. Elements vs. Compounds An element is. Examples:,. A compound is a combination of two or more that are combined. They are combined in a. Examples:,. Compounds cannot be separated by means. A must occur in order for the substance to separated. 4

5 Name Date Period Matter Substances vs. Mixtures All matter can be classified as either a substance (element or compound) or a mixture (heterogeneous or homogeneous). Matter Substance can write chemical formula; homogeneous Mixtures variable ratio Element one type of atom Compound 2 or more different atoms chemically bonded Homogeneous solutions Heterogeneous colloids & suspensions Directions: Classify each of the following as to whether it is a substance or a mixture. If it is a substance, write element or compound in the Substance column. If it is a mixture, write heterogeneous or homogeneous in the Mixture column. Type of Matter Substance Mixture 1. chlorine 2. water 3. soil 4. sugar water 5. oxygen 6. carbon dioxide 7. rocky road ice cream 8. alcohol 9. pure air 10. iron 5

6 Name Date Period Physical vs. Chemical Changes In a physical change, the original substance still exists, it has only changed form. In a chemical change, a new substance is produced. Energy changes always accompany chemical changes. Directions: Classify the following as being a physical or chemical change. 1. Sodium hydroxide dissolves in water Type of Change 2. Hydrochloric acid reacts with potassium hydroxide to produce a salt, water, and heat 3. A pellet of sodium is sliced in two 4. Water is heated and changed to steam 5. Potassium chlorate decomposes to potassium chloride and oxygen gas. 6. Iron rusts. 7. When placed in H2O, a sodium pellet catches on fire as hydrogen gas is liberated and sodium hydroxide forms 8. Evaporation 9. Ice melting 10. Milk sours 11. Sugar dissolved in water 12. Wood rotting 13. Pancakes cooking on a griddle 14. Grass growing in a lawn 15. A tire is inflated with air 16. Food is digested in the stomach 17. Water is absorbed by a paper towel 6

7 Name Date Period Physical & Chemical Properties A physical property is observed with the sense and can be determined without destroying the object. For example, color, shape, mass, length, and odor are all examples of physical properties. A chemical property indicates how a substance reacts with something else. The original substance is fundamentally changed in observing the chemical property. For example, the ability of iron to rust is a chemical property. The iron has reacted with oxygen, and the original iron metal has changed. It now exists as iron oxide, a different substance. Directions: Classify the following properties as either chemical or physical by putting a check in the appropriate column. 1. blue color 2. density 3. flammability 4. solubility 5. reacts with acid to form hydrogen gas (H2) 6. supports combustion 7. sour taste 8. melting point 9. reacts with water to form a gas 10. reacts with a base to form water 11. hardness 12. boiling point 13. can neutralize a base 14. luster 15. odor Physical Property Chemical Property 7

8 Science, Measurement, and Uncertainty: Accuracy and Precision ACCURACY AND PRECISION Definitions: Accuracy how close a measurement is to Precision how close a measurement is to Precision versus Accuracy: Look at each target and decide whether the hits are accurate, precise, both accurate and precise, or neither accurate nor precise: (Note: An accurate hit is a bulls eye!) Accurate?: Yes / No Precise?: Yes / No Accurate?: Yes / No Precise?: Yes / No Accurate?: Yes / No Precise?: Yes / No Precision Problems: A group of students worked in separate teams to measure the length of an object. Here are their data: Team 1 Team 2 Team 3 Team 4 Team 5 Team 6 Team cm 2.75 cm 2.80 cm 2.77 cm 2.60 cm 2.65 cm 2.68 cm The average length is cm. This is the mean or average. Subtract the highest value from the lowest value: cm. This is the range or spread. Divide this number by 2: cm. This is the approximate ± range from the average. The precision of the measurement can be shown as average ± range. The precision of the measurement was ± cm. 8

9 Science, Measurement, and Uncertainty: Accuracy and Precision A second group of students obtained the following data: Team 8 Team 9 Team 10 Team 11 Team 12 Team 13 Team cm 2.70 cm 2.80 cm 2.75 cm 2.65 cm 2.62 cm 2.78 cm The average length is cm. The precision of the measurement was ± cm. In comparing groups, the first or the second, which group was more precise or was the precision the same? Justify your answer. Expressing Errors in Measurement: Scientists often express their uncertainty and error in measurement by giving a percent error. The percent error is defined as: % error = actual value measured value actual value x 100 Answer the following four questions. Pay attention to significant figures, and show your work! 1. While doing a lab, a student found the density of a piece of pure aluminum to be 2.85 g/cm 3. The accepted value for the density of aluminum is 2.70 g/cm 3. What was the student's percent error? 9

10 Science, Measurement, and Uncertainty: Accuracy and Precision 2. A student measured the specific heat of water to be 4.29 J/g C o. The literature value of the specific heat of water is 4.18 J/g C o. What was the student s percent error? 3. A student took a calibrated gram mass, weighed it on a laboratory balance, and found it read g. What was the student s percent error? 4. Accuracy is often expressed as an average of several measurements. Look at the target to the right. In your opinion, how well do the measurements on the target represent: (Justify your opinion.) a. Accuracy? b. Precision? 10

11 CHEMISTRY Scientific Notation Practice A. Express the following numbers in correct scientific notation: B. Rewrite the following numbers so they are in correct scientific notation: x x x 10 8 C. Carry out the indicated operations and express your answer in correct scientific notation: 6. (3.04 x ) + (3.04 x ) 7. (6.54 x 10 5 ) - (2.0 x 10 3 ) 8. (2.5 x 10 3 ) (3.62 x 10 5 ) 9. (9.12 x 10 1 ) ( 6.55 x 10-2 ) 10. (3.2 x 10 2 ) (2.0 x 10-5 ) (3 x 10 4 ) 11. (3.80 x 10 4 ) (1.25 x 10-3 ) 12. (2.5 x 10-7 ) ( 5.0 x 10-8 ) (9.5 x ) (6.0 x 10 8 ) 13. ( ) ( ) 14. ( ) (87 000) 15. (3.5 x ) (1.47 x 10 6 ) (3.442 x 10-3 ) (9.97 x 10 5 ) (9 x ) (6.634 x 10 8 ) (2.7 x 10 4 ) (6.02 x ) 11

12 Significant Figures Practice Worksheet How many significant figures do the following numbers have? 1) ) ) 890 4) ) ) ) ) 3.4 x ) 9.0 x ) x ) ) ) ) ) ) ) ) ) x )

13 CHEMISTRY SIGNIFICANT FIGURE PRACTICE IV Write the number of significant figures in the following measurements x x x Round off the following numbers to three significant figures. (a) How many significant figures does each of the numbers contain? (a) meter (b) 1.3 centimeters (c) 1.00 foot (d) yards (e) 7.98 x 10-3 pound (f) ton (g) 4.69 x 10 4 tons (h) 1 x atoms (i) 1.73 x atoms 23. Express the following numbers in scientific notation with the indicated number of significant figures. (a) 1000 (2 sig. fig. ) (b) 43,927 (3 sig. fig.) (c) (3 sig. fig.) (d) (5 sig. fig.) (b) x 10 3 (c) (d) (e) x 10-3 (f)

14 CHEMISTRY SIGNIFICANT FIGURE PRACTICE V Do the following calculations and write your answer with the correct number of significant figures = x x 10-5 = = x 21 = x x 10 4 = x 460 = x x 10 5 = = x x 10-4 = x

15 READING MEASURING DEVICES NOTES Here are a couple of examples of graduated cylinders: Unit 1 Math & Measurement An important part of Chemistry is measurement. It is very important that you read the measuring devices we use in lab as accurately as possible. Here is how to determine how accurately a measuring device can be read: Look at the graduation marks on the piece of equipment. (Those are the lines or marks that are not numbered.) Decide what each mark is worth using the numbers given as a guide. You should read the instrument to one more decimal place to the right than the smallest graduation mark. This last number will be an estimate on your part. This will lead us into our next topic in measurement significant figures. A: Each of the smaller lines represents 1 ml. That means that our reading should be to one place to the right of the decimal point. To me, it looks like the bottom of the curve is about halfway between the 16 and the 17, so I would say that the reading on this graduated cylinder would be 16.5 ml. B: Each line represents 0.1 ml. That means that our reading should be to two places to the right of the decimal point. The bottom of the curve looks to me like it is exactly on the line that would represent 3.8. My reading, however, needs to be to two places to the right of the decimal. Because it is exactly on the line, my reading will be 3.80 ml. ======================================================= PRACTICE WITH READING MEASURING DEVICES WORKSHEET Part 1 - What are the readings on these metric rulers? Be sure to include units with your answers. 1.) 2.) 3.) 4.) 5.) Rulers, graduated cylinders, and thermometers on Practice With Reading Measuring Devices Worksheet are from math-aids.com 15

16 Unit 1 Math & Measurement Part 2 What are the readings on these graduated cylinders? Be sure to include units with your answers. 6.) 7.) 8.) 9.) 10.) 11.) 12.) 13.) Notes and Worksheets 16

17 Unit 1 Math & Measurement Part 3 What are the readings on these thermometers? Be sure to include units with your answers. 14.) 15.) 16.) 17.) Part 4 What are the readings on these triple beam balances? Be sure to include units with your answers. 18.) 19.) Notes and Worksheets 17

18 CHEMISTRY : DIMENSIONAL ANALYSIS PRACTICE 1. The distance from the thumb to the little finger on Jacob Grill's hand is 9 inches. Convert this to centimeters. 2. According to the Guinness Book of Records the heaviest baby ever born weighed 29 lbs 4 oz. (29.25 lbs). What was the baby's mass in kg? (Historical Note: The birth occurred in Effingham IL in 1939 and due to respiratory problems the baby died two hours later. The heaviest babies to survive weighed 22.5 lbs and were born in 1955 and 1982.) 3. Regan's cross country skis are 210 cm long. What is their length in inches? 4. A condor has a wing span of 3.05 m. What is the wing span in feet? 5. In Europe gasoline is sold by the liter. Assume that it takes 14 gallons of gasoline to fill the tank of a compact car. How many liters of gasoline will it take? 6. You have just received a French cookbook from the exchange student. You want to make 3 quarts of punch for a party. Will a recipe of 2.5 L be enough? 18

19 7. One 1.6 oz. of package of cinnamon and spice instant oatmeal contains 34 g of carbohydrates. If you had instant oatmeal 6 days a week, how many ounces of carbohydrate would you consume in a week? (16 oz =1 lb = 454 g = 256 Drams = 7000 Grains) 8. Many candybars have 9 g of fat per bar. If during a "chocolate attack" you ate one pack of candy (0.6 dekabars), how many ounces of fat would you have eaten? There are approximately 9 Calories per gram of fat, how many Calories is this? 9. If the RDA for vitamin C is 60 mg per day and there are 70 mg of vitamin C per 100 g of orange, how many 3 oz. oranges would you have to eat each week to meet this requirement? 10. Because you never learned dimensional analysis, you have been working at a fast food restaurant for the past 35 years wrapping hamburgers. Each hour you wrap 184 hamburgers. You work 8 hours per day. You work 5 days a week. You get paid every 2 weeks with a salary of $ How many hamburgers will you have to wrap to make your first one million dollars? 11. Mark McGuire hit 70 home runs in the 1998 season. Given that there are 4 bases with 90 feet between each base, how many miles did he run last season just from home runs? 12. A high School senior was applying to college and wondered how many applications she needed to send. Her counselor explained that with the excellent grade she received in chemistry she would probably be accepted to one school out of every three to which she applied. [3 applications = 1 acceptance] She immediately realized that for each application she would have to write 3 essays, [1 application = 3 essays] and each essay would require 2 hours work [1 essay = 2 hours]. Of course writing essays is no simple matter. For each hour of serious essay writing, she would need to expend 500 calories [1 hour = 500 calories] which she could derive from her mother's apple pies [1 pie = 1000 calories]. How many pies would she have to eat in order to gain acceptance to 10 colleges? 19

20 CHEMISTRY METRIC DIMENSIONAL ANALYSIS 1. Calculate the number of kilometers (km) there are in 105 meters (m). 2. How many millimeters are there in 5.97 x 10-6 meters (m)? 3. Calculate the number of kilometers (km) there are in micrometers (mm). 4. Calculate the number of centimeters (cm) there are in kilometers (km). 5. A very small object is found to have a length of 3.44 x 10-4 meter (m). Express this length in micrometers (mm). 6. How many decigrams (dg) are there in microgram (mg)? 7. How many kilograms (kg) are there in x 10 3 milligram (mg)? 8. Calculate the number of milligrams (mg) in 6.2 x 10 4 micrograms (mg). 9. How many cubic decimeters (dm 3 ) are there in x 10 5 cubic meters (m 3 )? 10. The volume of a sample of water is found to be 86.3 cubic centimeters (cm 3 ). What is the volume of the sample in cubic millimeters (mm 3 )? 20

21 Name Period Density Worksheet In order to receive full credit, you must show ALL work and circle your final answer grams of a liquid completely fill a 200 ml bottle. What is the density of the liquid? 2. A solution has a density of 1.50 g/ml. How many grams are needed to obtain 10.0 ml of solution? 3. If a block of copper measures 2.00 cm x 4.00 cm x 5.00 cm and weighs 356 grams, what is its density? 4. The density of mercury is 13.6 g/ml. a. what is the mass of 8.20 ml of mercury? b. what volume would 120 grams of mercury occupy? 5. A piece of silver has a mass of 2800 grams and occupies a volume of 266 cm 3. What is the density of silver? 21

22 6. A bottle has a capacity of 1.2 liters. If the density of ether is 0.74 g/ml, what mass of ether can the bottle hold? 7. A student pipets 5.00 ml of ethanol into a flask weighing grams. She finds that the mass of the flask plus ethanol = grams. Calculate the density of ethyl alcohol. 8. Peanut oil has a density of 0.92 g/ml. If a recipe calls for ¼ cup of peanut oil, what mass of peanut oil is required? (Hint: 1 cup = 237 ml). 9. A chemist needs 2.00 g of a liquid compound, which has a density of g/ml. If the compound costs $5.67 per ml, how much will a 2.0 gram sample cost? 22