Houston Community College System. Chemistry 1305 Spring 2018 EXAM # 1A

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1 Houston Community College System Chemistry 105 Spring 018 EXAM # 1A

2 HOUSTON COMMUNITY COLLEGE CHEM 105 Exam # 1, Chapters 1 (Corwin 7 th Edition) Name: Score: PART I Multiple choice: ( points each) 1) Which of the following is a basic step in the scientific method? A) Perform an experiment and collect data. B) Analyze experimental data and propose a hypothesis. C) Test a hypothesis and state a theory or law. D) all of the above ) Which of the following statements is a natural law? A) The mass of substances, before and after a chemical change, is the same. B) If the volume of a gas doubles, the pressure decreases by a factor of two. C) The energy derived from a change in mass is found by E = mc. D) all of the above ) What is the term for a direct change of state from a gas to a solid? A. Condensation B. Deposition C. Sublimation D. Vaporization E. None of these ) Which of the following properties of ethyl alcohol is a physical property? A. colorless liquid B. density, g/ml C. boiling point, 78.5 C D. specific heat, cal/(g x C) E. All of these 5) What subject is said to be at the crossroads of biology, physics, and geology? A) biochemistry B) chemistry C) environmental chemistry D) geochemistry 6) Which of the following properties of gasoline is a chemical property? A. boiling point, 97 C B. density, 0.69 g/ml C. burns with air D. insoluble in water E. colorless liquid 7) What is the term for the inexactness of an instrumental measurement? A) accuracy B) error C) precision D) uncertainty 8) Which of the following metric rulers has the least uncertainty? A) Ruler A, ± 1 cm B) Ruler B, ± 0.1 cm C) Ruler C, ± 0.5 cm D) Ruler D, ± 0.05 cm 9) How many significant figures are there in the number ? A) B) 5 C) 7 D) 9

3 10) Express the number in scientific notation. A. ⅹ 10-6 B.. ⅹ 10 C.. ⅹ 10 D.. ⅹ 10 - E. 0. ⅹ 10-11) Convert 59. mi to km. (1 m = 1.09 yd, 1 mi = 1760 yd) A. 6.5 ⅹ 10 1 km B..69 ⅹ 10 1 km C ⅹ 10 7 km D. 5. ⅹ 10 1 km E ⅹ 10 1 km 1) Calculate /1.650 and report to the correct number of significant figures. A..1 B..15 C. 5.1 D. 5.1 E..1 1) Which of the following is an example of a physical change? A. adding vinegar to baking soda and producing carbon dioxide B. grinding sucrose crystals and producing powdered sugar C. smoking tobacco and producing smoke and ash D. digesting starch and producing glucose sugar E. None of these 1) What is the symbol for the metric unit micrometer? A) cm B) mm C) Mm D) μm 15) What is the name corresponding to the metric symbol ml? A) megaliter B) metroliter C) microliter D) milliliter 16) According to the metric system, 1 = 1,000,000 g. A) Gg B) Mg C) kg D) μg 17) Which of the following laws states that energy cannot be created or destroyed? A. law of conservation of energy B. aw of conservation of mass C. law of conservation of mass and energy D. law of definite composition E. None of these 18) Which of the following describes a substance in the gaseous physical state? A) The substance has a variable shape. B) The substance has a variable volume. C) The substance compresses significantly. D) all of the above 19) What is the term for stored energy that matter possesses related to its position or chemical composition? A. heat energy B. kinetic energy C. mechanical energy D. potential energy E. None of these 0) Cyanocobalamin, C 6H 88CoN 1O 1P, is vitamin B 1. What is the number of atoms in one molecule of vitamin B 1? A. 1 B. 179 C. 180 D. 181 E. None of these

4 PART II Show All Your Work: (8 points each) 1) Magnesium is one of the least dense elements (d = 1.7 g/cm ). What is the volume of a 10.0 g sample of the metal? ) A piece of tin foil has a volume of 0.65 mm. If the piece measures 10.0 mm by 1.5 mm, what is the thickness of the foil in mm? ) An antifreeze solution freezes at -100 C. What is the freezing point on the Fahrenheit scale? ) Liquid krypton boils at 11 K. What is the boiling point on the Celsius scale? 5) A hybrid vehicle has a mileage rating of km/l. What is the gas mileage in miles per gallon? (Given: 1 mi = 1.61 km, and 1 gal =.78L) BONUS QUESTION Show All Your Work: (10 points) Calculate /1.650 and report to the correct number of significant figures.

6 Soluble Compounds 1) All compounds of the alkali metals (Group IA) ) All salts containing ) All are soluble. combined with Ag ) All sulfates are soluble except those of Pb Hg salts containing Cl, Br, or I are soluble except when, and Ba Insoluble Compounds 6) All NH, NO, ClO, ClO, and C H O, Pb of Group IA and of Ca salts that contain PO hydroxides. The oxide ion, O, and Hg, Sr, CO except those of Group IA and NH, SO.., and Ba, and S, Ca oxides do dissolve, they react with water to form are soluble., Sr 5) All metal hydroxides and oxides are insoluble except those - -. When metal, does not exist in water , are insoluble, Activity Series Electronegativity Li H.1 K Li 1.0 Ba Na 0.9 Ca B.0 Na C.5 Mg N.0 Al O.5 Zn F.0 Cr Cl.0 Fe Cd Br.8 Co I.5 Ni Sn S.5 Pb Se. H Cu Ag Hg Pt Au Constants/ Relationships density = mass/volume Avogardo s number = 6.0 x 10 things/mol E = q + w q = mass x specific heat x t 1 cal =.18 J K = C + 7 F = (9/5)( C) + Planck s constant = h = 6.6 x 10 J s Speed of light = c =.00 x 10 8 m/s c = 1 J = 1 kg m s - R H =.18 x J E = h 1 E R H 1 n i n f Gas constant = R = L atm mol -1 K -1 PV = nrt d = (PM)/(RT) Molar volume of a gas =. L at STP STP = 1 atm and 0 C 1 atm = 760 mm Hg = 760 torr

M = Molarity = mol solute L solution. PV = nrt % yield = actual yield x 100 theoretical yield. PM=dRT where d=density, M=molar mass

M = Molarity = mol solute L solution. PV = nrt % yield = actual yield x 100 theoretical yield. PM=dRT where d=density, M=molar mass Solubility Rules: 1. Most nitrate salts are soluble. 2. Most salts of alkali metals and ammonium cations are soluble. 3. Most chloride, bromide and iodide salts are soluble. Exceptions: salts containing