Name Class Date. Section: Measurements and Calculations in Chemistry

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1 Skills Worksheet Concept Review Section: Measurements and Calculations in Chemistry Answer the following questions in the space provided. 1. What is the difference between accuracy and precision? 2. Suppose a chemistry student took the mass of a sample of calcium carbonate and obtained the following values: 1.01 g, 1.00 g, 0.99 g, 0.98 g. The known mass was 1.00 g. Was this measurement accurate or precise? Explain your answer. 3. Determine the number of significant figures in the following. a g f g b. 3 cars g g c g h g d g i g e. 100 g j. 20 students 4. Explain why some numerical values have an unlimited number of significant digits. Holt Chemistry 5 Matter and Energy

2 Concept Review continued Solve the following problems, and write your answer in the space provided. 5. Perform the following operations. Express your answers with the correct number of significant figures. a m 2.7 m m b ml 2 L 137 ml 10 L c kpa ml / 547 kpa d. 346 ml 200 K / K 6. Convert the following to scientific notation. a mm b mg c m d g/cm 3 7. Perform the following calculations. Express your answers in scientific notation. a b. ( )( ) c / d e f g. ( )(2.00) h / Three chemistry students measured the length of a copper bar. The recorded lengths were 5.05 cm, 5 cm, and 5.1 cm. What is the average length of the bar? Holt Chemistry 6 Matter and Energy

3 Concept Review continued 9. Find the volume of a cube of zinc with the following dimensions: cm, 3.1 cm, 2.99 cm. 10. Find the density in g/cm 3 of a rectangular prism with dimensions of mm, mm, 3147 mm and a mass of g. 11. Find the average volume from the following volume readings: 3.00 ml, 2.0 ml, ml, and ml. Holt Chemistry 7 Matter and Energy

4 TEACHER RESOURCE PAGE Answer Key Concept Review: Energy 1. energy 2. physical 3. chemical 4. endothermic 5. exothermic 6. kinetic 7. transferred 8. In any chemical or physical change, the total quantity of energy remains constant. Energy cannot be created or destroyed. 9. Heat is the enegy transferred between objects that are at different temperatures. 10. Temperature is a measure of how hot or cold something is; specifically, a measure of the average kinetic energy of the particles in a sample of matter. 11. Heat is the energy transferred between objects that are at different temperatures, and temperature is the measurement of the average kinetic energy of the particles in a sample of matter. 12. a K b. 20 C c K d C e C f K 13. Specific heat is the amount of heat required to raise the temperature of 1 g of a substance by 1 K. 14. Substance B will have the higher temperature. Each gram of substance B requires half as much energy to raise its temperature as does substance A. Concept Review: Studying Matter and Energy 1. observing, formulating hypotheses, testing hypotheses, analyzing results, drawing conclusions, publishing results 2. The research findings of any experiment or investigation must be reproducible by other scientists for those findings to be accepted as valid. The results must be verifiable. 3. A scientist must know for certain that the variable is in fact causing the result to occur and that it would not have happened if the variable had not been changed. 4. A variable is any aspect of an experiment that can be changed to affect the outcome of the experiment. 5. A model is a simplified representation of an object, a system, a process, or an idea. 6. Models are used to represent abstract ideas. A model gives scientists a visual aid so that they may test or envision a smaller or larger-scaled replica of the actual item. 7. b 8. a 9. d 10. c Concept Review: Measurements and Calculations in Chemistry 1. Accuracy is the extent to which a measurement approaches the true value of a quantity; precision is the extent to which a series of measurements of the same quantity made in the same way agree with one another. 2. Answers may vary. Look at the defense of the answer. 3. a. 7 b. unlimited c. 3 d. 10 e. 1 f. 10 g. 1 h. 7 i. 10 j. unlimited 4. These values are not measured; they are counted. They are not subject to measuring inaccuracies. They are exact. Holt Chemistry 109 Matter and Energy

5 TEACHER RESOURCE PAGE 5. a m b ml c. 151 ml d. 100 ml 6. a mm b mg c m d g/cm 3 7. a b c d e f g h cm cm g/cm ml Additional Problems SIGNIFICANT FIGURES 1. a. 3 b. 4 c. 3 d. 2 e. 2 f. 1 g. 3 h. 4 i a m b ml c cm 2 d m 2 e. 790 cm f J g cm 3 3. a cm 2 b. 3.1 kg/l c L/sec d cm 3 e. 41 m 3 f g/cm 3 4. a J b m c. 900 g d kpa e. 278 dl f kg 5. a. 307 cm 2 b mm 2 c m 2 6. a cm 3 b m 3 c mm 3 7. a kg/m 3 b. 1.3 g/ml c. 1.3 kg/dm 3 8. a. 130 mm 3 b. 430 cm 3 c. 5.0 m d m m a g b mg c L d. 315 cm 2 e kg f. 353 ml kg/l g/m; 2.3 m m kj/min; 439 kj/s 15. a m 3 b L/min c. 590 m 3 /h 16. a. 7.5 kg m 2 b cm c. 2.4 kg m 2 /s 2 d m 2 e m/h f. 139 cm 2 SCIENTIFIC NOTATION 1. a km b L c cm 3 d mm 2 e g f m g J h g/l i kg j Hz 2. a kg b mg c m 3 d m e J f molecules g cm Holt Chemistry 110 Matter and Energy