CHEM 110 Final

If 25g of each reactant were used in performing the following reaction, which would be the limiting reactant? 3PbO2 + Cr2(SO4)3 + K2SO4 + H2O -> 3PbSO4 + K2Cr2O7 + H2SO4

3:1 ratio PbO2 = 25g(1mol/239g/mol) = .105mol Cr2(SO4)3 = 25g(1mol/392g/mol) = .064mol x 3 = .192mol K2SO4 = 25g(1mol/174g/mol) = .144mol H2O = 25g(1mol/18g/mol) = 1.38mol PbO2

The sum 2.834 + 5.71520 + 2.12 + 178.1 + 250.2619 expressed to the proper number of significant figures is:

439.0

Consider the element indium, atomic number 49. The nucleus of an atom of indium-112 contains

49 protons, ...

Suppose 600g of P4 reacts with 1300g of S8. How many grams of P4S10 can be produced, assuming 80% yield based on the limiting reactant? 4P4 + 5S8 -> 4P4S10

4:5 Ratio P4 = 600g(1mol/123.896g/mol) = 4.842mol/4 = 1.2105mol S8 = 1300g(1mol/256.52g/mol) = 5.067mol/5 = 1.0134mol 5.067mol S8(444.546g P4S10/1mol P4S10) x (4mol P4S10/5mol P4S10) = 1802.011g P4 80% = Actual/1802.011g Actual = 144160.88g

How many sigma (σ) bonds and how many pi (π) bonds does the ethene molecule contain? C2H4, H** H**C** **C**H **H

5 σ, 1 π

Find the molarity of 40% by mass aqueous solution of sulfuric acid, H2SO4, for which the density is 1.3057g/mL?

1.3057g/mL x 1000mL = 1305.7g 1305.7g x 40% = 52228g H2SO4 52228g H2SO4/98.076g/mol H2SO4 532.525M

What angle(s) are associated with a central atom that has tetrahedral electronic geometry?

109.5*

Caffeine, a stimulant in coffee and some cola drinks, is 49.47% Carbon, 5.19% Hydrogen, 28.8% Nitrogen, and 16.48% Oxygen. What is the mass of Carbon contained in 37.1g of caffeine?

.4947g Carbon(37.1g) 18.4g

The electron configuration for the carbon atom is _____.

1s^2 2s^2 2p^2

What is the electron configuration of sulfur, S?

1s^2 2s^2 2p^6 3s^2 3p^4

Identify the number of π bonds contained in this molecule. Butadiene, C4H6

2

When you draw the Lewis structure for H2O, how many single bonds, double bonds, and lone pair electrons reside on the central oxygen atom?

2 single bonds, 0 double bonds, 2 lone pairs

Which Lewis Dot notation for atoms and ions is correct for the reaction for the formation of aluminum oxide?

2**Al* + 3** *Cl** * -> 2Al^3+, 3[** **O** **]^2-

The answer to the following calculation, rounded to the proper number of significant digits: 23.413g / (2.15cm x 1.1cm x 3.73cm)

2.7g/cm^3

How many shared pairs of electrons are in the outer shell of the central nitrogen atom of NH4?

3

What is the symbol for a species composed of 35 protons, 44 neutrons, and 36 electrons?

35p + 44n = 79 36e - 35p = 1 79/35 Br-

Identify the number of σ bonds contained in this molecule. Butadiene, C4H6

9

A compound contains, by mass, 26.7% Carbon, 71.1% Oxygen and the remainder Hydrogen. A 0.23 mole sample of this compound weighs 20.7g. What is the molecular formula of this compound?

C = .267g(1mol/12.011g/mol) = .022mol/.021mol = 1x2 = 2 O = .711g(1mol/15.999g/mol) = .044mol/.021mol = 2x2 = 4 H = .022g(1mol/1.007g/mol) = .021mol/.021mol = 1x2 = 2 C2H2O4

What is the wavelength of yellow light having a frequency of 5.17 x 10^14Hz?

C = λ x v 3 x 10^8m/s = λ x 5.17 x 10^14 Hz (1/s) 3 x 10^8m/s/5.17 x 10^14 Hz (1/s) = λ x 5.17 x 10^14 Hz (1/s)/5.17 x 10^14 Hz (1/s) 5.80 x 10^-7m

Which of the following substances contains two pi bonds?

C2H2

Determine the oxidation number of the underlined element in K2CO3?

CO3 C + 3(-2) = -2 C + (-6) = -2 C = +4

What is the formula for the ionic compound formed between calcium and sulfur?

Ca 2+, S 2- Ca2S2 CaS

Which response includes all of the species listed below that have the electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^6? Cl-, Na+, K+, Ar, P^3-

Cl-, K+, Ar, and P^3-

A chemical bond formed by two atoms sharing one or more pairs of electrons is called a(n) ___ bond.

Covalent

Write a balanced equation for the reaction between the dichromate ion and iron(II) to yield iron(III) and chromium(III) in acidic solution.

Cr2O7^2- + Fe^2+ -> Cr^3+ + Fe^3+ Cr2O7^2- -> Cr^3+ , F Fe^2+ -> Fe^3+ 14H+ + Cr2O7^2- -> 2Cr^3+ + 7H2O 6e- + 14H+ + Cr2O7^2- -> 2Cr^3+ + 7H2O 6Fe^2+ + 14H+ + Cr2O7^2- -> 6Fe^3+ + 2Cr^3+ + 7H2O

From the following compounds choose the name / formula pair that is incorrectly matched?

Cuprous / Co2S

Write and balance the formula unit, total ionic, and net ionic equations for the oxidation of sulfurous acid to sulfuric acid by oxygen in acidic aqueous solution.

Formula unit: 2H2SO3(aq) + O2(g) -> 2H2SO4(aq) Total Ionic: 2H2SO3(aq) + O2(g) -> 4H+(aq) + 2H2SO4^2-(aq) Net Ionic: 2H2SO3(aq) + O2(g) -> 4H+(aq) + 2H2SO4^2-(aq)

What is the formula for the binary compound of gallium and chlorine?

GaCl3

Which of the following is the correct Lewis Dot formula for H2S?

H**S** **H

5.57g of Hydrogen gas was reacted with excess Iodine, according to the following reaction H2(g) + I2(g) -> 2HI(g) If 505g of HI was actually collected, what was the percent yield of HI?

H2 = 5.57g(1mol/2.0158g/mol) = 2.7631mol 2.7631mol H2(127.907g HI/1mol HI) x (2mol HI/1mol HI) = 706.814g HI % Yield = 505g/706.814g %Yield = 71%

Which one of the following molecules is polar?

H2O

What are the oxidation numbers (oxidation states) of the elements in H3PO2?

H3PO2 3(+1) P + 2(-2) = -1 3 P + (-4) = -1 H = +1, P = +1, O = -2

Which of the following is an ionization?

HBr(g) -> H+(aq) + Br-(aq)

Which of the following are paired incorrectly?

HClO4 - Weak Acid

What is the total ionic equation for the following formula unit equation? HF(aq) + KOH(aq) -> KF(aq) + H2O(l)

HF(aq) + [K+(aq) + OH-(aq)] -> [K+(aq) + F-(aq)] + H2O(aq)

Write the chemical formula for: nitric acid

HNO3

Each response below lists an ion by name and by chemical symbol or formula. Also each ion is classified as monatomic or polyatomic and as a cation or anion. Which response contains an error?

Hydroxide / OH- / Monatomic / Anion

The oxidation state of iodine in IO3^- is _____.

IO3^- I + 3(-2) = -1 I + (-6) = -1 +5

Which of the following statements about ionic and covalent compounds is false?

Ionic compounds have low melting points

Calculate the percent composition of K2CO3.

K = 2(39.098mol) = 78.196mol C = 1(12.011mol) = 12.011mol O = 3(15.999mol) = 47.997mol Total = 138.204mol K = 78.196mol/138.204mol x 100% = 56.6% C = 12.011mol/138.204mol x 100% = 8.7% O = 47.997mol/138.204mol x 100% = 34.7% %K = 56.6%, %C = 8.7%, %O = 34.7%

Complete the following conversions between SI units: a) 781mL = ___L b) 8.160m = ___cm c) 3779ug = ___g d) 27.8m = ___km e) 5.18kg = ___g

KHDUDCM a) 0.781L b) 816cm c) .003779g d) 0.0278km e) 5180g

What is the concentration of the NaCl solution that results when 0.150L of a 0.556M solution is allowed to evaporate until the volume is reduced to 0.105L?

M1 x V1 = M2 x V2 0.556M x 0.150L = *M2* x 0.105L M2 = 0.794M

Calculate the mass of one Bromine atom.

Mass = 6.022 x 10^23mol/79.904g/mol 1.327 x 10^-22g

You have two samples of the same gas in the same size container, with the same pressure. The gas in the first container has a Kelvin temperature four times that of the gas in the other container. The ratio of the number of moles of gas in the first container compared to that in the second is:

Ref: 7-2

You have a 400-mL container containing 55.0% He and 45.0% Ar by mass at 25°C and 1.5 atm total pressure. You heat the container to 100°C. Calculate the total pressure.

Ref: 7-4

Which Lewis Dot formula is incorrect?

SO3^2-

Determine the oxidation number of the underlined element in SO4^2-.

SO4 S+4(-2) = -2 S+(-8) = -2 S = +6

Which element has the electron configuration below? 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^4

Se

If the following set of quantum numbers represents the "last" electron added to complete the ground state electron configuration of an element according to the Aufbau Principle, which one of the following could be the symbol for the element? n = 3, l = 1, ml = 0, ms = +- 1/2

Si

Which one of the following species is not isoelectronic with neon?

Si^2+

Liquid propane boils at 231K. What is its boiling point in *C?

T(K) = T(*C) + 273 231K = T(*C) + 273 -42*C

The electronic geometry of the central atom in PCl3 is ___.

Tetrahedral

The fact that O2 is paramagnetic can be explained by:

The Lewis structure of O2

The electronic geometry is:

The arrangement of regions of high electron density around the central atom in a molecule

When a solution is diluted, what is the relationship of the number of moles of solute in the more concentrated initial volume of solution to the number of moles of solute in the less concentrated final volume of solution?

The number of moles of solute in both solutions is the same

According to the VSEPR model, the arrangement of electron pairs around NH3 and CH4 is:

The same, because in each case there are the same number of electron pairs around the central atom

What statement regarding quantum numbers is false?

The spin quantum number has values of either +1 or -1

Which of the following is a characteristic that describes nonmetals?

Their solids shatter when hammered

The molecular structure of NCl3 is:

Trigonal pyramidal

The number of electrons present in the s orbitals in the outermost electron shell of the alkaline earth (group IIA) metal is ___.

Two

The Lewis Dot formula for CO2 shows:

Two double covalent bonds

The molecular structure of H2O is:

V-shaped (bent)

Which of the following is the correct Lewis structure for the electron configuration 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 5s^2 4d^10 5p^6 6s^2

X**

How many paired electrons are shown in a Lewis Dot Formula for silicon?

[K]+

Polymers are large molecules composed of simple units repeated many times. Thus, they often have relatively simple empirical formulas. Calculate the empirical formulas of the following polymers: a) Lucite (Plexiglas): 59.9% C, 8.06% H, 32% O b) Saran: 24.8% C, 2% H, 73.1% Cl

a) C = 59.9g(1mol/12.011g/mol) = 5mol H = 8.06g(1mol/1.0079g/mol) = 8mol O = 32g(1mol/15.999g/mol) = 2mol C5H8O2 b) C = 24.8g(1mol/12.011g/mol) = 2mol H = 2g(1mol/1.0079g/mol) = 2mol Cl = 73.1g(1mol/35.453g/mol) = 2mol CHCl

Classify each of the following as an element, a compound, or a mixture: a) Copper b) Water c) Air d) Sucrose

a) Element b) Compound c) Mixture d) Compound

What is the name of the following compounds: a) KOH b) Na2SO4 c) PBr3

a) Potassium hydroxide b) Sodium sulfate c) Phosphorus tribromide

Provide the number of protons, electrons, and neutrons in neutral atoms of the following isotopes: a) 10/5 B b) 199/80 Hg c) 63/29 Cu

a) Proton = 5, Neutron = 5, Electron = 5 b) Proton = 80, Neutron = 119, Electron = 80 c) Proton = 29, Neutron = 34, Electron = 29

A 1.488g sample of an element contains 8.708 x 10^21 atoms. What is the element symbol?

n = 8.708 x 10^21 Atoms(1mol/6.022 x 10^23 Atoms) n = .0144mol Molar Mass = 1.488g Sample/.0144mol Molar Mass = 103.333g/mol Rh

What would be the outer electron configuration of group VIA (O, S, Se, ...)?

ns^2np^4

What kind of hybrid orbitals are utilized by the boron atom in BF3 molecule?

sp^2

The hybridization associated with the central atom of a molecule in which all the bond angles are 109.5* is ___.

sp^3

Which Lewis Dot Formula below is incorrect?

**B

An element has the following electronic configuration in its outermost shell. In simple ionic compounds the oxidation number of this element would be ___. ns up/down

+2

Which of the following is the best definition of a salt?

A compound that contains a cation other than H+ and an anion other than OH- or O^2

If an element consisted of three isotopes in the following relative abundance, what would the atomic weight of the element be? This is a hypothetical example. 30% 37amu 50% 38amu 20% 40amu

AW = (.3 x 37amu) + (.5 x 38amu) + (.2 x 40amu) 38.10amu

Which element has the largest atomic radius?

Al

Dalton's Atomic Theory included all of the ideas listed below except:

An element is composed of very small particles called protons, neutrons, and electrons

Which one of the following pairs of molecules and molecular geometries is incorrectly matched? Compound / Molecular Geometry

BeBr2 / Angular

Which of the following is a halogen?

Br

Which of the following bonds is least polar?

Br-Br

The energy of a photon of light is 1.5 x 10^-20J. What is its wavelength?

E = h x c/λ 1.5 x 10^-20J = (6.626 x 10^-34J*s) x (3 x 10^8m/s)/λ 1.5 x 10^-20J λ/1.5 x 10^-20J = 1.9878 x 10^-25J*m/1.5 x 10^-20J 1.33 x 10^5A

A property that measures the ability of an atom to attract electrons in a chemical bond is:

Electronegativity

Iodine is most likely to form an ionic compound with ___.

Mg

A species with 12 protons and 10 electrons is _____.

Mg^2+

The negative ion F- has the same electronic configuration as the positive ion ___.

Mg^2+

Determine the oxidation number of the underlined element in NHs-.

NH2 N+2(+1) = -1 N+2 = -1 N = -3

Which of the following compounds has the most ionic bond?

NaF

Which of the following has the smallest radius?

Ne

Which molecule exhibits resonance?

O3

Following a scientific method, which of the following is the correct order of steps?

Observation -> Hypothesis -> Experiment -> Analysis -> Conclusion -> Communicate results

An atom of which element below has the most unpaired electrons?

P

The molecule geometry of PCl3 is ___.

Pyramidal

List the following colors of visible light from longest wavelength to shortest wavelength: green, blue, yellow, red, violet

Red > yellow > green > blue > violet

Aqueous solutions of barium chloride and silver nitrate are mixed to form solid silver chloride and aqueous barium nitrate. The balanced complete ionic equation contains which of the following terms?

Ref: 10-1

Consider the following electronegativity values: C 2.5, Cl 3.0, H 2.1, O 3.5, Select from the following group the molecule that has the least polar bonds between its atoms: a)CHCHO b)CO c)CHCl d)CH e)none

Ref: 4-1

Consider the molecule and the following hybridization choices: What is the hybridization of the carbon atom that is double-bonded to oxygen?

Ref: 5-1