AVOGADRO EXAM 2014 - Answers

1 What is the SI unit for amount of substance? 5 Which of the following has the largest covalent radius?

A gram A carbon, C

B kilogram B fluorine, F

*C mole *C silicon, Si

D millilitre D sulfur, S

E litre E chlorine, Cl

2 Mercury has a density of 13.6 g mL−1 at 0 oC and 6 Which of the following statements concerning HCl is 101 kPa. For this condition of temperature and not correct? pressure, what is the volume of 50.0 grams of mercury? A It is a strong acid in water.

*A 3.68 mL B The oxidation state of chlorine is −1.

2 B 6.80×10 mL C It is a stronger acid than HF.

C 0.272 mL *D The bond between hydrogen and chlorine is primarily ionic. D 63.6 mL E It is a gas at 25 oC and 101 kPa. E 36.4 mL

7 Treatment of C12H22O11 (table sugar) with excess concentrated H2SO4 yields a black residue (pure carbon) 3 How many protons, neutrons and electrons are 3 − and water vapour. What is the maximum mass of carbon there in a single H ion? that can be obtained from exactly one gram of C12H22O11?

A one neutron, one proton, one electron A 0.035 g

*B two neutrons, one proton, two electrons B 0.083 g

C one neutron, three protons, two electrons C 0.12 g

D three neutrons, one proton, one electron D 0.27 g

E three neutrons, one proton, two electrons *E 0.42 g

8 There are only two naturally-occurring isotopes of gallium. 4 Which of the following exists as an atomic gas at 25 oC and 101 kPa? gallium-69: 68.925581 u gallium-71 70.924705 u If the weighted atomic mass of gallium is 69.723 u, then A hydrogen what is the percent abundance of gallium-71?

B chlorine A 33.8%

C bromine *B 39.9%

D sulfur C 50.7%

*E krypton D 60.1%

9 Which pair of compounds is most similar in their 13 Both HClO4 and HCl are strong acids. Which of the physical and chemical properties? following provides evidence that HClO4 is a stronger acid than HCl? *A HCl and HBr A When dissolved in water, both HClO4 and HCl B H2O and H2S ionize completely.

C CO2 and SiO2 B The boiling point of HClO4 is higher than that of HCl.

D CH3OH and B(OH)3 C Commercial preparations of concentrated HClO4 are typically 70% HClO4 by mass whereas commercial E HCl and NaOH preparations of HCl are about 38% HCl by mass.

*D When dissolved in acetic acid (CH3COOH), HClO4 10 When the Kelvin temperature of a fixed amount of an ionizes to a greater extent than does HCl. ideal gas is doubled and the pressure is doubled, what is the combined effect on the volume of the gas? E Copper metal dissolves readily in a concentrated solution of HClO4 but not in concentrated HCl *A The volume remains constant. solution.

B The volume increases by a factor of two. 14 What is the general formula of the hydrides formed by C The volume increases by a factor of four. the elements (E) of group 15?

D The volume decreases by a factor of two. A EH

E The volume decreases by a factor of four. B EH2

C E2H 11 What is the correct electron arrangement for a nickel

(Ni) atom? (The first number in each list refers to the *D EH3 number of electrons in the first shell; the second

number refers to the number of electrons in the E EH4 second shell; and so on.)

A 2, 6, 10, 10 15 Which second-period atom has the greatest number of unpaired electrons in its lowest energy state? B 10, 10, 8 *A nitrogen, N C 2, 8, 2, 8, 2, 6 B oxygen, O *D 2, 8, 16, 2 C fluorine, F E 2, 8, 8, 8, 2 carbon, C D 12 Which set of coefficients properly balances the E boron, B equation below? + 2+ Zn(s) + Ag (aq) → Zn (aq) + Ag(s) 16 Which of the following equations is not correct?

A 1, 1, 1, 1 A Br2 + energy → 2 Br

B 2, 1, 2, 1 B IF + energy → l+ + F−

− − *C 1, 2, 1, 2 C F + e → F + energy

D all of the above D CO2(g) → CO2(s) + energy − − *E O2 + energy → O + O E none of the above

17 Which combination of elements will most likely form 21 What volume does 11.0 kg of carbon dioxide occupy an ionic compound? at 0 oC and 101.3 kPa?

A hydrogen and fluorine 3 A 2.47×10 L

B sodium and magnesium 3 *B 5.60×10 L

*C magnesium and oxygen C 11.0 L

D oxygen and chlorine D 577 L

E silicon and oxygen E 247 L

18 A solid sample of impure carbon is 84% C by mass. 22 In the reaction below, which element is reduced? How many carbon atoms are there in a 71.0 g sample? 8 KI + 9 H2SO4 → 4 I2 + 8 KHSO4 + H2S + 4 H2O

24 A 2.5×10 A potassium (K) 24 B 2.1×10 B iodine (I) 24 *C 3.0×10 C hydrogen (H) D 3.0×1025 *D sulfur (S) E 2.5×1025 E oxygen (O)

19 What gas is produced when ammonium nitrate, 23 When 25 mL of 0.10 mol L−1 HBr(aq) is mixed with NH4NO3, is added to NaOH(aq) and the solution −1 gently heated? 25 mL of 0.20 mol L KOH(aq), what is the pH of the final solution at 25 oC? A hydrogen peroxide, H2O2 A 1.00 B oxygen, O2 B 1.30 C dinitrogen tetroxide, N2O4 C 7.00 *D ammonia, NH3

E nitric oxide, NO *D 12.70

E 13.00

20 What is the maximum amount of HNO3 that can be obtained from 4.50 moles of NO and 3.00 moles of 2 24 What is the formula of copper(II) nitride? H O according to the following equation? 2 *A Cu3N2 3 NO2 + H2O → 2 HNO3 + NO B Cu2N *A 3.00 moles C Cu(NO3)2 B 6.00 moles D Cu2NO3 C 7.50 moles E Cu2N3 D 6.75 moles

E 5.00 moles

25 What is the pressure of the gas in the apparatus 28 In an experiment, a 1.52 gram sample of solid KClO3 below if the atmospheric pressure is 764 mmHg? is decomposed by heating to produce KCl and 310 mL of O gas at 25.0 oC and 103 kPa. What is the 2 percent yield for this experiment?

A 59%

*B 69%

C 78% Gas 48 mm D 87%

22 mm mercury (Hg) E 96%

A 26 mmHg 29 Analysis of a solution of Co2(SO4)3 establishes that 2− −1 the concentration of SO4 is 0.060 mol L . What is B 70 mmHg the concentration of Co3+ in this solution?

738 mmHg −1 C A 0.010 mol L * 790 mmHg −1 D B 0.030 mol L

E 834 mmHg *C 0.040 mol L−1

D 0.060 mol L−1 26 Suppose the atomic mass scale had been set up with −1 calcium (Ca) assigned a mass of 10 u. What would E 0.090 mol L be the approximate atomic mass of oxygen?

A 1.6 u 30 Which of the following is an isomer of diethyl ether, *B 4.0 u CH3CH2OCH2CH3? C 8.0 u A butanal, CH3CH2CH2CHO D 64 u B dimethyl ether, CH3OCH3 E 160 u *C t-butyl alcohol, (CH3)3COH

D butanoic acid, CH3CH2CH2COOH 27 An unidentified metal X forms a compound with chlorine in which 1.036 g of X are present for E butan-2-one, CH3CH2COCH3 every 0.3545 g of chlorine. The empirical formula of the compound is XCl2. What is the atomic symbol for X? 31 Which compound contains oxygen in the highest (most positive) oxidation state? A Hg A KO3 B Mg B K2O2 C Ba *C F2O D Rh D K2O *E Pb E NO2

32 Which of the following statements is not correct? 35 Which of the following is the Lewis structure (i.e., the best electron dot structure) for the N − ion? Deviations from ideal gas behaviour are 3 A more significant at high pressures. A N N N B Attractive intermolecular forces cause a decrease in the observed pressure of a gas N N N compared to what is predicted for an ideal gas. *B

C Deviations from ideal gas behaviour are more significant at very low temperatures. C N N N

*D At very high pressures, the observed molar volume of a gas is smaller than what is D N N N predicted for an ideal gas. N E For low to moderate pressures, attractive E intermolecular forces are the primary cause of N N deviations from ideal gas behaviour.

+ −3 −1 36 A gaseous compound contains hydrogen, carbon and 33 A solution has [H ] = 3.7×10 mol L . What is nitrogen. If combustion of 1.0 L of the compound in the pH of this solution ? oxygen yields 2.0 L CO2, 3.5 L of H2O and 0.50 L of N2, all measured at the same temperature and pressure, *A 2.43 what is the empirical formula of the compound?

B 3.57 A CHN

C 3.70 B CH2N2

D 4.04 C C4H7N

E 5.60 D CH4N7

*E C2H7N

34 A container of helium gas, initially at 217 kPa and 5.00 oC, is heated to 80.0 oC. The container is opened briefly to allow some gas to escape and 37 In a well-insulated container, an endothermic reaction then it is closed. If the final pressure is 93.0 kPa, takes place. When the reaction is done, the what fraction of the helium gas remains in the temperature of the contents will be container? A higher than before the reaction began A 0.15 B higher or lower than at the start of the reaction *B 0.34 depending on the masses of reactants used

C 0.42 C independent of the heat capacities of the substances involved D 0.58 D the same as before the reaction began E 0.79 *E be lower than before the reaction began

38 Which of the following is less soluble in hot water than in cold water?

A glucose, C6H12O6

*B methane, CH4

C silver chloride, AgCl

D silver nitrate, AgNO3

E sodium hydroxide, NaOH

39 At high temperatures, hydrogen iodide (HI) reacts reversibly according to the following equation.

2 HI(g)   H2(g) + I2(g)

In an experiment, an initial reaction mixture containing 0.100 mol each of HI, H2 and I2 at room temperature is prepared and then heated to a high temperature. After some time has passed, the amount of HI in the system is found to be.0.120 moles. What is the amount of H2 in the system at that time?

A 0.120 moles

B 0.110 moles

*C 0.090 moles

D 0.080 moles

E 0.060 moles

−1 40 A 6.00 mol L aqueous solution of CsCl is 58.0% CsCl by mass. What is the density of this solution? Molar masses A 0.586 g/mL (in g/mol) H2O, 18.02 B 0.842 g/mL CsCl, 168.35

C 1.01 g/mL

*D 1.74 g/mL

E 16.3 g/mL