Chem 1 Exam MC

The molarity of a solution prepared by diluting 43.72 mL of 1.005 M aqueous K2Cr2O7 to 500. mL? A. 0.0879 B. 87.9 C. 0.0218 D. 0.0115

A (0.0879)

When 7.00 × 1022 molecules of ammonia react with 6.00 × 1022 molecules of oxygen according to the chemical equation shown below, how many grams of nitrogen gas are produced? 4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(g) A. 1.63 g B. 1.86 g C. 4.19 g D. 6.51 g

A (1.63 g)

What is the total number of σ bonds in one molecule of this compound? A. 14 B. 12 C. 9 D. 27

A (14)

What is the de Broglie wavelength of a C60 molecule (m = 1.20 x 10-24 kg) traveling at 220 m/s? (1 m = 1 x 1012 pm) A. 2.52 pm B. 2.52 m C. 1.20 pm D. 5.22 m

A (2.52 pm)

Which ion contains 12 protons, 14 neutrons, and 10 electrons? A. 26Mg2+ B. 26Mg2- C. 24Si2+ D. 24Si2-

A (26Mg2+)

How many total lone pairs (not shown) exist in one molecule of this compound? (Think Octet Rule here). A. 4 B. 3 C. 2 D. 1

A (4)

According to the following reaction, how much energy is evolved during the reaction of 0.111 mol B2H6 and 0.252 mol Cl2 (Both gases are initially at STP)? B2H6(g) + 6 Cl2(g) → 2 BCl3(g) + 6 HCl(g) ΔH°rxn = -1396 kJ A. 58.7 kJ B. 156 kJ C. 215 kJ D. 352 kJ

A (58.7 kJ)

Which is the correct formula for the binary compound that results from the reaction below? Al (s) + N2 (g) → __________ A. AlN B. Al3N C. Al N2 D. Al3N2

A (AlN)

Which species contains the most polar-covalent bonds? A. CF4 B. CO2 C. CN- D. CH4

A (CF4)

Which of the following is an oxidation-reduction reaction? A. Cu (s) + 2AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq) B. HCl (aq) + NaOH (aq) → H2O (l) + NaCl (aq) C. AgNO3 (aq) + HCl (aq) → AgCl (s) + HNO3 (aq) D. Ba(C2H3O2)2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaC2H3O2(aq)

A (Cu (s) + 2AgNO3 (aq) → 2Ag (s) + Cu(NO3)2 (aq))

The energy change for an electronic transition in a one-electron atom or ion from ninitial to nfinal is where Z is the atomic number. Which one of the following species will have the longest wavelength emission line for the transition between the ninitial = 2 and nfinal = 1 levels? A. H B. He+ C. Be3+ D. B4+

A (H)

Which law states that all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements? A. Law of Definite Proportions B. Law of the Conservation of Mass C. Coulomb's Law D. Law of Multiple Proportions

A (Law of Definite Proportions)

Which of the following ionic compounds would be expected to have the highest lattice energy? A. LiF B. LiCl C. LiBr D. LiI

A (LiF)

Which combination will produce a precipitate? A. Pb(NO3)2 (aq) and HCl (aq) B. Cu(NO3)2 (aq) and KC2H3O2 (aq) C. KOH (aq) and HNO3 (aq) D. AgC2H3O2 (aq) and HC2H3O2 (aq)

A (Pb(NO3)2 (aq) and HCl (aq))

What is the oxidation number for S in Na2S2O5? A. +5 B. +4 C. +2 D. + 1

B (+4)

A gas bottle contains 0.250 mol of gas at 730 mm Hg pressure. If the final pressure is 1.15 atm, how many moles of gas were added to the bottle? A. 0.0262 mol B. 0.0493 mol C. 0.276 mol D. 0.299 mol

B (0.0493 mol)

How many moles and how many atoms of Zn are in a 34.9-g sample? A. 0.534 mol Zn and 8.85 x 10-25 atoms Zn B. 0.534 mol Zn and 3.21 x 1023 atoms Zn C. 1.87 mol Zn and 3.10 x 10-24 atoms Zn D. 1.87 mol Zn and 1.13 x 1024 atoms Zn

B (0.534 mol Zn and 3.21 x 1023 atoms Zn)

What is the N—O bond order in NO3- ion? A. 1 B. 1.33 C. 1.5 D. 1.75

B (1.33)

In the diagram below, helium atoms are represented by unshaded spheres, neon atoms by gray spheres, and argon atoms by black spheres. If the total pressure in the container is 900 mm Hg, what is the partial pressure of helium? A. 90 mm Hg B. 180 mm Hg C. 270 mm Hg D. 450 mm Hg

B (180 mm Hg)

What is the root-mean-square speed of a neon atom at 27°C? A. 5.78 m/s B. 19.3 m/s C. 183 m/s D. 609 m/s

B (19.3 m/s)

Which electron configuration shows an excited-state oxygen atom? A. 1s2 2s2 2p2 B. 1s2 2s2 2p2 3s2 C. 1s2 2s2 2p1 D. 1s22s2 2p4

B (1s2 2s2 2p2 3s2)

Which would be classified as synthesis reactions? 1) CH4(g) + O2(g) → CO2(g) + H2O(l) 2) CaO (s) + CO2 (g) → CaCO3 (s) 3) Mg (s) + O2 (g) → MgO (s) 4) PbCO3 (s) → PbO (s) + CO2 (g) A. 1, 2, and 3 B. 2 and 3 C. 1, 2, 3, and 4 D. 4 only

B (2 and 3)

A 25.0 mL graduated cylinder has a mass of 30.450 g. Metal pellets are added and the total mass increases to 129.812 g. The cylinder is filled to the 25.0 mL mark with methanol, which has a density of 0.792 g/cm3. The combined mass of the cylinder, metal, and methanol is 140.255 g. Calculate the density of the pellets. A. 9.84 g/cm3 B. 8.41 g/cm3 C. 9.51 g/mL D. 7.54 g/mL

B (8.41 g/cm3)

Which is the molecular formula for this compound? (Remember to include hydrogens not shown.) A. C4H5N2O B. C4H8N2O C. C4H6N2O D. C4N2OH2

B (C4H8N2O)

Which graph represents the relationship between gas density (y-axis) and temperature (x-axis)? A. Positive diagonal B. L shape C. Negative diagonal D. Horizontal line

B (L shape)

In which covalent bond does the underlined atom bear a δ+ charge? A. F—P B. N—I C. Cl—Sb D. Al—Br

B (N—I)

Which reaction below represents the second electron affinity of S? A. S(g) + e− → S−(g) B. S−(g) + e− → S2−(g) C. S(g) → S+(g) + e− D. S−(g) → S(g) + e−

B (S−(g) + e− → S2−(g))

Which of the following processes is endothermic? A. The reaction associated with the lattice energy of LiCl B. The reaction associated with the ionization energy of potassium C. The reaction associated with the combustion of CH4 D. The formation of F2 from its elements in their standard states

B (The reaction associated with the ionization energy of potassium)

Assuming all have the same principal-quantum number (n) value and are found in a multi-electron atom, which is lowest in energy? A. Picture of d orbital B. Picture of s orbital C. Picture of d orbital D. Picture of p orbital

B (s orbital)

Use the information provided to determine ΔH°rxn for the following reaction. 3 Fe2O3(s) + CO(g) → 2 Fe3O4(s) + CO2(g) ΔH°rxn = ? ΔH°f (kJ/mol): Fe2O3(s) -824, Fe3O4(s) -1118, CO(g) -111, CO2(g) -394 A. +277 kJ B. -577 kJ C. -47 kJ D. +144 kJ

C (-47 kJ)

How many moles of CuO can be produced from 0.450 mol of Cu2O and excess O2 in this reaction? 2 Cu2O(s) + O2(g) → 4 CuO(s) A. 0.225 mol B. 0.450 mol C. 0.900 mol D. 1.80 mol

C (0.900 mol)

A five-year-old child suffering a potentially fatal allergic reaction to peanuts needs an emergency injection of 0.12 mg of epinephrine from a bottle labeled 100 μg epinephrine per mL of solution. What volume of this solution should the child receive? A. 0.012 mL B. 0.12 mL C. 1.2 mL D. 12 mL

C (1.2 mL)

What is the total number of π bonds in one molecule of this compound? A. 8 B. 6 C. 2 D. 0

C (2)

Determine the specific heat capacity of an alloy that requires 59.3 kJ to raise the temperature of 150.0 g alloy from 298 K to 398 K. A. 4.38 J/g°C B. 2.29 J/g°C C. 3.95 J/g°C D. 2.53 J/g°C

C (3.95 J/g°C)

Given sulfur can expand its octet, how many bonding electron pairs must surround S in SO2 order to yield a formal charge of 0 for S? A. 2 B. 3 C. 4 D. 5

C (4)

A 45.0-L steel tank at 20.0°C contains acetylene gas, C2H2, at a pressure of 1.39 atm. Assuming ideal behavior, how many grams of acetylene are in the tank? A. 2.60 g B. 10.0 g C. 67.8 g D. 990 g

C (67.8 g)

Which element is most electrically conductive? A. At B. P C. Ag D. S

C (Ag)

Which compound has a trigonal-planar molecular structure? A. ClF3 B. PF3 C. BF3 D. XeF3+

C (BF3)

Which if the following acids is considered strong? A. HN3 B. HNO2 C. HNO3 D. N2H4

C (HNO3)

A glass tube has one end in a dish of mercury and the other end closed by a stopcock. The distance from the surface of the mercury to the bottom of the stopcock is 800 mm, as indicated by the meter stick shown. The apparatus is at 20°C, and the mercury level in the tube is the same as that in the dish. Which drawing best shows the approximate level of the mercury in the tube when the temperature of the entire apparatus is lowered from +20°C to -20°C? A. drawing (1) B. drawing (2) C. drawing (3) D. drawing (4)

C (drawing 3)

How many significant figures are there in the answer for the following problem? [(131.7-119)×1.05] = 0.500 A. four B. three C. two D. one

C (two)

Calculate the change in internal energy (ΔE) for a system that is giving off 25.0 kJ of heat and is changing from 18.00 L to 15.00 L in volume at 1.50 atm pressure. (Remember that 101.3 J = 1 Latm) A. +25.5 kJ B. -16.0 kJ C. -25.5 kJ D. -24.5 kJ

D (-24.5 kJ)

Use the bond energies provided to estimate ΔH°rxn for the reaction below. XeF2 + 2 F2 → XeF6 ΔH°rxn = ? Bond: Xe-F, F-F Bond Energy (kJ/mol): 147, 159 A. -429 kJ B. +159 kJ C. -660 kJ D. -270 kJ

D (-270 kJ)

A 21.8 g sample of ethanol (C2H5OH) is burned in a bomb calorimeter, according to the following reaction. If the temperature rises from 25.0 to 62.3°C, determine the heat capacity of the calorimeter. The molar mass of ethanol is 46.07 g/mol. C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(g) ΔH°rxn = -1235 kJ A. 4.99 kJ/°C B. 5.65 kJ/°C C. 63.7 kJ/°C D. 15.7 kJ/°C

D (15.7 kJ/ºC)

Which is the coefficient of SO2 when the equation below is balanced using smallest, whole numbers? ______ PbS (s) + _____ O2 (g) → _____ PbO (s) + _____ SO2 (g) A. 5 B. 1 C. 3 D. 2

D (2)

What is the energy per mole of photons emitted by a sodium lamp with wavelength of 589 nm? A. 3.37 x 10-9 kJ/mol B. 120 kJ/mol C. 70.5 kJ/mol D. 203 kJ/mol

D (203 kJ/mol)

Based on your knowledge of s, p, d, and f orbitals, what is the maximum number of electrons that an h subshell can contain? A. 11 B. 9 C. 18 D. 22

D (22)

Given that the N represented with an arrow participates in a process similar to that below, how many total bonds lack free rotation in one molecule of the fungus-derived compound? A. 0 B. 1 C. 2 D. 3

D (3)

Considering your answer to (13), how many total sp2-hybridized atoms are in one molecule of the fungus-derived compound (At very top of this page)? A. 0 B. 2 C. 4 D. 5

D (5)

Which results from a reaction between strontium hydroxide and perchloric acid? A. A molecular compound and a weak electrolyte B. Two weak electrolytes C. Two strong electrolytes D. A molecular compound and a strong electrolyte

D (A molecular compound and a strong electrolyte)

The following diagrams represent the reaction of A2 (shaded spheres) with B2 (unshaded spheres). Identify the limiting reactant and a balanced equation for the reaction. A. A2 is the limiting reactant; A + 3 B → AB3 B. A2 is the limiting reactant; A2 + 3 B2 → 2 AB3 C. B2 is the limiting reactant; A + 3 B → AB3 D. B2 is the limiting reactant; A2 + 3 B2 → 2 AB3

D (B2 is the limiting reactant; A2 + 3 B2 → 2 AB3)

Which is the correct formula for nitric acid? A. HNO2 B. HN3 C. H3N D. HNO3

D (HNO3)

Given their bond lengths (in pm), which is expected to have a highest bond-dissociation energy? A. H—Cl (127 pm) B. H—I (161 pm) C. H—Br (141 pm) D. H—F (92 pm)

D (H—F 92 pm)

If each of the following is exposed to incident light with λ = 240 nm, which emits electrons with the greatest kinetic energy? A. Fe (wf = 7.2 x 10-19 J) B. Pt (wf = 9.1 x 10-19 J) C. Ni (wf = 8.3 x 10-19 J D. Na (wf = 4.4 10-19 J)

D (Na)

The electrostatic potential energy (Eel) between a pair of charged particles is proportional to their charges, Q1 and Q2, and inversely proportional to the distance between the centers of the ions, d. Oppositely charged particles attract each other while like particles repel. Which statement is true? A. As Q1 and Q2 both increase, potential energy decreases B. If d is doubled, Q1 is doubled, and the potential energy doubles C. As d increases between oppositely charged particles, potential energy decreases D. Potential energy decreases, as the distance between two like-charged particles increases

D (Potential energy decreases, as the distance between two like-charged particles increases)

In which are the elements organized in order of increasing atomic radius? A. C < N < F B. Rb < K < Li C. Sc < Ge < Br D. Se < Cu < Ca

D (Se < Cu < Ca)

Which one of the following compounds is insoluble in water? A. Na2CO3 B. K2SO4 C. Fe(NO3)3 D. ZnS

D (ZnS)

Which has a maximum of three ml values? A. Picture of d orbital B. Picture of s orbital C. Picture of d orbital D. Picture of p orbital

D (p orbital)