1 CHEM 10050 Fall 1995 Exam #1 Name _____________________ Soc. Sec.# _________________ Conversion factors: 1 mile = 1.61 km, 1 in. = 2.54 cm, 1 kg = 2.205 lb, 1 lb = 454 g, 1 L = 1.057 qt., 1 qt. = 946 mL, 4.184 J = 1 cal, 32 oz. = 1 qt., 4 qt. = 1 gallon, 2 pt. = 1 qt. heat Equations: sp. ht. = g x ∆T Multiple Choice (3 pts. each) ____ 1) Which of the following is not a diatomic element? a) bromine b) hydrogen c) carbon d) oxygen ____ 2) Aspirin has a density of 1.40 g/cm 3. What is the volume of a tablet weighing 500 mg? a) 0.357 cm3 b) 0.700 cm3 c) 357 cm3 d) 2.80 cm3 ____ 3) Which of the following is a chemical change? a) ice melting c) salt dissolving b) sulfur burning d) water evaporating ____ 4) Which substance has definite shape and definite volume in addition to a regular repeating three dimensional pattern at the atomic level? a) a gas b) an amorphous solid c) a liquid d) a crystalline solid ____ 5) Which of the following numbers has three significant figures? a) 0.014 b) 0.007 c) 0.3705 d) 0.000324 ____ 6) Which element has the largest radius? a) F b) Al c) Cl d) K ____ 7) Isotopes always have the same: a) mass number c) number of neutrons b) atomic number d) none of these 52 ____ 8) An atom of 24 Cr contains: a) 52 protons b) 52 electrons c) 28 neutrons d) 28 protons ____ 9) Which subatomic particle has a relative mass of approximately one mass unit and a charge of 0? 2 a) neutron b) proton c) electron d) alpha particle 3 ____ 10) You are in a closed room that is filling with deadly phlogiston gas. The specific gravity of this gas is 0.985. How should you leave? a) walk out b) crawl out c) who knows? d) stay and die! ____ 11) The prefix “micro-” used in the metric system indicates: a) 10-3 b) 10-6 c) 10-9 d) 10-12 c) 268 K d) none of these ____ 12) 23 °F is equivalent to: a) 5.0 °C b) 12 °C ____ 13) Substances that are metals are: a) lustrous c) good conductors of heat and electricity b) ductile d) all of these ____ 14) A piece of gold (Au) with a specific heat of 0.317 J/g°C requires 730 J to change its temperature from 34.0°C to 80.0°C. What is the mass of this piece of gold? a) 1.06 x 104 g c) 0.0200 g b) 50.0 g d) 15.9 g ____ 15) Equal amounts of heat are added to two objects of equal mass. The object with the highest specific heat will: a) increase in temperature the most. c) not increase in temperature. b) increase in temperature the least. d) none of these ____ 16) The modern periodic table is arranged in: a) b) c) d) order of increasing atomic weight order of increasing number of atoms order of increasing number of neutrons order of increasing number of protons ____ 17) Exactly 11.4 g of Mg reacts with 15.0 g S to give the compound magnesium sulfide (MgS). What percentage of the compound is magnesium (Mg)? a) 50.0% b) 56.8% c) 43.2% d) 31.6% ____ 18) Which of the following is a transition element? a) Na b) Br c) Zn d) Si ____ 19) _____ states that electrons cannot enter a half filled shell if an empty one is available. a) The Pauli Exclusion Principle c) The Octet Rule b) Hund’s Rule d) Lewis Dot Rule ____ 20) Which of the following is a mixture? a) sulfur b) water c) air d) carbon dioxide 4 5 Solve the following problems showing all work. Remember to use proper units, significant figures and rounding. 1) Give the complete electronic configuration and electron diagram for arsenic. Also, represent this element using a Lewis Dot Structure. (10 pts.) 2) Forgetful Freddie placed 45.0 mL of a liquid into a graduated cylinder and then placed what appeared to be a “diamond” weighing 22.345 g into the cylinder. The volume of the liquid in the cylinder subsequently rose to 53.1 mL. The density of diamond is 3.500 g/mL. Did Freddie celebrate finding an authentic diamond? Show calculations to support your answer. (5 pts.) 3) Do the following conversions using the appropriate number of significant figures (10 pts.): a) 23.6 pounds to milligrams b) 26.0 miles to millimeters c) 34 years to seconds 6 d) 29.5 milliliters to microliters 7 4) What dosage in grams per kilogram of body weight does a 185 lb man receive if he takes two 500 mg tablets of erythromycin? How many 125 mg tablets should a 46 lb child take to receive the same dose? (10 pts.) 5) Naturally occurring silver exists as two stable isotopes. 107Ag with a mass of 106.9041 amu (51.82% natural abundance) and 109Ag with a mass of 108.9047 amu (48.18% natural abundance). Calculate the average atomic mass of silver. (5 pts.)