Benchmark Mid-Term Study Guide

1. Benchmark Mid-Term Study Guide

2. Chapter 1: Introduction to Chemistry A systematic approach that scientists use: • Scientific method • 1. Observation • 2. hypothesis • 3. experiment • results/Data • Conclusions • 6. theory • 7. law

3. Matching B ___ 6. refers to physical characteristics such as color, odor, or shape ___ 7. refers to mass, volume, and temperature measurements ___ 8. a variable controlled by the experimenter ___ 9. the act of gathering information ___ 10. changes in value based on the value of the controlled variable a. Observation b. Qualitative data c. Quantitative data d. Independent variable e. Dependent variable C D A E

4. Multiple Choice • A constant is a factor that a. Changes during an experiment b. Changes from one lab group to another c. Is affected by the dependent variable d. Is not allowed to change during an experiment

5. Matching • A control is a. Variable that changes during an experiment b. Standard for comparison c. Type of dependent variable d. Type of experiment

6. Matching • A hypothesis is a(n) a. Educated Guess b. Explanation supported by many experiments c. Tentative explanation of observations d. Law describing a relationship in time

7. Matching • A theory is a(n) a. Set of controlled observations b. Explanation supported by many experiments c. Tentative explanation of observations d. Law describing a relationship in time

8. Matching • A law is a(n) a. Set of controlled observations b. Explanation supported by many experiments c. Tentative explanation of observations d. Law describing a relationship in time

9. Matching • A model is a(n) A visual, verbal, or mathematical. GRAPH, Pie Chart

10. Completion • What piece of lab equipment should be used to accurately measure volume? • What piece of lab equipment should be used to accurately measure mass? • What is the proper technique for smelling a chemical in the laboratory? • What is the proper technique for holding a test tube while heating? Graduated cylinder Balance Wafting Test tube holder

11. Chapter 2: Data Analysis • Change the following data into scientific notation. a. 5,000,000 km b. 0.000421 g c. 0.03 cm 5 x 106 km 4.21 x 10-4 g 3 x 10-2 cm

12. Change the following data into ordinary notation. a. 5.3 x 1012 b. 4.0 x 105 c. 6.1 x 10-5 5,300,000,000,000 400,000 0.000061

13. 3.Use the terms precise and accurate to describe the following figures. You may use both terms for some figures. If a term does not apply to a figure, leave the space blank. neither Precise but Not accurate Accurate & precise

14. Students were asked to find the density of an unknown white powder. Each student measured the volume and mass of three separate samples. They reported calculated densities for each trial and an average of the three calculations in the following data table. The power was sucrose, also called table sugar, which has a density of 1.59 g/cm3. a. Which student’s measurements were most accurate? b. Which student’s measurement were most precise? A – because all of their values are close to the accepted value of sugar, 1.59% C – because all of their values are close together but not close to the accepted value

15. 5. A sample of aluminum is placed in a 25 mL graduated cylinder containing 10.0 mL of water. The level of water rises to 18.0 mL. Aluminum has a density of 2.7 g/mL. Calculate the mass of the sample. (Use appropriate significant figures.) • 18.0 mL m = d(v) • 10.0 mL = 2.7 g/mL(8.0mL) • 8.0 mL = 21.6g = 22g

16. 6. You have a 230g sample of ethanol with a density of 0.7893 g/mL. What volume of ethanol do you have? (use appropriate significant figures) v = m/d = 230g 0.7893g/mL = 291.4 = 290 mL

17. 7. An object with a mass of 7.5g raises the level of water in a graduated cylinder from 25.1 mL to 30.1 mL. What is the density of the object? • 30.1 mL d = m/v 7.5g = 1.5 g/mL • 25.1 mL 5.0mL • 5.0 mL

18. 64.0 mL • Determine the volume indicated in Figure 1. • Determine the length indicated by Letter H in Figure 2. 10. Determine the volume indicated in Figure 3. 12.94 cm 34.7 °C Figure 3 Figure 1 Figure 2

19. Chapter 3 – Matter: Properties & Changes mass Matter is anything with (1) ____________________ and volume. A (2) ____________________ is a form of matter with a uniform and unchanging composition. Substances have specific, unchanging (3) ____________________ that can be observed. Substances have both physical and chemical properties. (4) ____________________ properties can be observed without changing a substance’s chemical composition. Color, hardness, and (5) ____________________ are examples. Other properties cannot be observed without changing the composition of a substance. These are called (6) __________________ properties. An example is the tendency of iron to form rust when exposed to air. substance properties physical density chemical

20. Label each property as either physical intensive, physical extensive, or chemical. Physical-intensive Physical-extensive Physical-intensive Chemical Physical-intensive Chemical Physical-extensive Chemical Intensive – doesn’t matter how much you have Extensive – does matter how much you have

21. _____ 15. A solid has definite shape and volume. _____ 16. A liquid has a definite shape and takes on the volume of its container. _____ 17. A gas has both the shape and the volume of its container. _____ 18. The particles in a solid are spaced far apart. True False True False

22. gas solid liquid 19. ____________ 20. ____________ 21. ____________

23. What are the four indicators that a chemical change has taken place? a. Temperature change b. Color change c. Gas (bubbles) produced d. Precipitate (solid) formed

24. Identify the following as physical or chemical changes P C C C P C P P

25. intermediate visible/large homogeneous heterogeneous positive negative No Yes Clear Cloudy

26. compound heterogeneous homogeneous element compound heterogeneous

27. List four techniques that can be used to separate a mixture. • Filtration • Distillation • Chromatography • crystallization

28. Chapter 4 – The Structure of the Atom + 1 Inside nucleus Outside nucleus - 0 0 1 Inside nucleus

29. nucleus • Most of an atom’s mass can be found in the ______________. • The number of protons in an atom is its ________________. • The number of protons + neutrons in an atom is its ______________. • In a neutral atom, the number of ______ always equals the number of __________. • Isotopes are atoms of an element with a different ________. They have the same number of ________ but a different number of ____________. atomic # mass # protons electrons mass # protons neutrons

30. Use a periodic table to identify the following elements. a. 47 protons b. 95 electrons c. Atomic number = 28 d. 6 protons and 8 neutrons Ag - silver Am - americium Ni - nickel Carbon – 14 or 14 6 C

31. 16 8 8 8 8 O 7 9 Nitrogen - 16 80 35 35 Br Bromine - 80

32. 36 18 38 18 40 18 9. Three isotopes of argon occur in nature – Ar, Ar, and Ar. Calculate the average atomic mass of argon to two decimal places, given the following relative atomic masses and abundances of each of the isotopes: argon–36 (35.97 amu; 0.337%), argon–38 (37.96 amu; 0.063%), and argon–40 (39.96 amu; 99.600%). 35.97 (0.00337) = 0.1212 37.96 (0.00063) = 0.0239 39.96 (0.996) = 39.800 39.945 amu

33. Chapter 25: Nuclear Chemistry 2. Nuclear reactions involve changes in an atom’s nucleus, whereas chemical reactions do not.

34. 4 2 He 0 -1 e energy