CHEMISTRY PRACTICE EXAM #1

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1 CHEMISTRY PRACTICE EXAM #1 Section 1 - Match the phrases with a correct term from the list at the bottom of the page. Place the letter of the correct term in the blank next to the phrase or definition. (Answers may be used more than once.) E 1. Your weight changes when you go to the moon, but your does not C 2. A pure substance consisting of only one type of atom H 3. A specific example of an element classified as a metal R 4. The weighted average of the isotopic masses of the isotopes present in an element M 5. A general name for a group of elements which tend to give up electrons to form cations O 6. The total number of protons and neutrons in the nucleus of an atom A 7. Anything which occupies space and has mass I 8. The ratio of mass to volume, a constant physical property of a substance L 9. G 10. F 11. B The unique number of protons in the nucleus of an atom of a specific element Atoms joined together in a specific geometric arrangement through sharing electrons The comparison between a measured value and the true value for the measurement 12. A measure of the reproducibility of a measurement Q 13. A specific example of an element classified as a nonmetal J 14. The subatomic particle found in the nucleus and having no net charge N 15. S 16. D A general name for a group of elements which tend to gain electrons to form anions An atom which differs from another atom only in the number of neutrons in the nucleus 17. A pure substance composed of 2 or more elements in a fixed, definite proportion. K 18. The subatomic particle having a unit negative charge A. matter B. precision C. element D. compound E. mass F. accuracy G. molecule H. potassium I. density J. neutron K. electron L. atomic number M. metal N. nonmetal O. mass number P. atom Q. oxygen R. atomic mass S. isotope T. proton V. atom

2 Section 2 - This section of the exam is multiple choice. Choose the BEST answer from the choices which are given and write the letter for your choice in the space provided. All questions are equally weighted and there is no penalty for guessing. 1. Which of the following represents a physical property? A. Sodium metal is extremely reactive with chlorine gas. B. Mercury is a silver liquid at room temperature. C. The tendency of iron to rust D. The flammability of butane fuel 2. Choose the pure substance from the list below A. tea B. a spinach casserole C. carbon monoxide D. sugar water 3. Choose the heterogeneous mixture from the following A. gatorade B. chlorine gas C. black coffee D. chicken noodle soup 4. A chemical change A. occurs when methane gas is burned. B. occurs when paper is shredded. C. occurs when water is vaporized. D. occurs when salt is dissolved in water. 5. How many significant figures are in x 10 4? A. 3 B. 4 C. 5 D How many significant figures are in the measurement g? A. 4 B. 5 C. 6 D The average distance from Earth to the Sun is 150 megameters. What is that distance in meters? A. 1.5 x 10 8 m B. 1.5 x 10 6 m C. 1.5 x 10 5 m D. 1.5 x 10 3 m 8. The mass of a sample is 550 milligrams. Expresses that mass in kilograms? A. 5.5 x 10 8 kg B. 5.5 x 10 5 kg C. 5.5 x 10-4 kg D. 5.5 x 10-6 kg

3 9. Isopropyl alcohol, commonly known as rubbing alcohol, boils at 82.4 C. What is the boiling point in kelvins? K = (ºC ) A K B K C K D K 10. Acetic acid boils at F. What is its boiling point in degrees Celsius? ºC = (5/9)*(ºF ) A C B C C C D C 11. Which of the following correctly expresses g in scientific notation? A x 10 6 g B x 10 5 g C x 10-5 g D x 10-6 g 12. A student performs an experiment to determine the density of a sugar solution. She obtains the following results: 4.71 g/ml, 4.73 g/ml, 4.67 g/ml, 4.69 g/ml. If the actual value for the density of the sugar solution is 4.40 g/ml, which statement below best describes her results? A. Her results are precise but not accurate. B. Her results are accurate but not precise. C. Her results are both precise and accurate. D. Her results are neither precise nor accurate. 13. What does X represent in the following symbol? X A. mercury B. chlorine C. scandium D. bromine 14. What species is represented by the following information # or protons = 17, # neutrons = 18, #electrons = 18 A. Cl B. Cl - C. Ar D. Ar Which of the following statements is FALSE according to Dalton s Atomic Theory? A. All atoms of chlorine have identical properties that distinguish them from other elements. B. One carbon atom will combine with one oxygen atom to form one molecule of carbon monoxide. C. Atoms of sodium do not change into another element during chemical reaction with chlorine. D. An atom of nitrogen can be broken down into smaller particles that will still have the unique properties of nitrogen.

4 16. Which of the following statements about subatomic particles in TRUE? A. A neutral atom contains the same number of protons and electrons. B. Protons have about the same mass as electrons. C. Electrons make up most of the mass of an atom. D. Protons and neutrons have opposite, but equal in magnitude, charges. 17. Identify the compound with ionic bonds. A. Ne B. KBr C. O2 D. H2O 18. What is the empirical formula for C4H10O2? A. C2H5O B. CHO C. C2H4O D. CHO2 19. Give a possible molecular formula for a compound with the empirical formula C3H5ClO. A. C6H10ClO2 B. C5H10Cl2O2 C. C6H10Cl2O2 D. C6H10O2 20. Which of the following is a molecular compound? A. CuCl2 B. KCl C. NaNO3 D. CH3Cl Section 3 - Complete the following tables!!! 1. Complete the following table for the following neutral atoms with the correct symbols and integers. Symbol # protons # neutrons # electrons 35 Cl Au Complete the following table for the following ions with the correct symbols and integers. Symbol # protons # electrons charge Br As

5 Section 4 - Show all of your work for full credit (consider sig fig!!!!!!)!!!!!!!!!!!!! (19 pts) 1. The speed needed to escape the pull of Earth's gravity is 11.3 km/s. What is this speed in mi/h? (1.61 km =1.00 mi) 2.53 x 10 3 Answer: mi/hr 2. A block of metal has dimensions 3.50 cm x cm x 1.00 cm. What is the density of the metal if the block has a mass of g Answer: g/ml 3. How many xenon atoms are in 2.36 moles of xenon (Xe)? (Avogadro s # = 6.02 x atoms/mol) 1.42 x Answer: atoms 4. What is the mass of 2.63 moles of nickel (Ni)? 154 Answer: g

6 5. What is the mass of 1.9 x atoms of lead (Pb) 650 Answer: g 6. Ammonium sulfate, (NH 4 ) 2 SO 4, is a fertilizer widely used as a source of nitrogen. Calculate its molar mass. (Show work.) Answer: g/mol 7. A compound contains mass % N, 4.20 mass % H, and mass % O. Its molar mass is between 94 and 98 g/mol. a. If the mass% s give ratios of masses, what is the ratio of moles? (Show work.) N2.082H4.17O4.16 b. What is the empirical formula of the compound? (Show work.) NH2O2 c. What is the molecular formula of the compound? N2H4O4

Principles of Chemistry: A Molecular Approach (Tro) Chapter 2 Atoms and Elements

Principles of Chemistry: A Molecular Approach (Tro) Chapter 2 Atoms and Elements 1) Which of the following is an example of the law of multiple proportions? A) A sample of chlorine is found to contain