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Exam 4 hw

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The density of octane is 0.703 g/mL. What mass (in g) will a 1.791 gallon sample of octane have?

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Classify the properties as extensive or intensive.

Mass	Choose...	extensive	intensive	-
Density	Choose...	extensive	intensive	-
Color	Choose...	extensive	intensive	-
Volume	Choose...	extensive	intensive	-
Total energy	Choose...	extensive	intensive	-
Temperature	Choose...	extensive	intensive	-
Melting point	Choose...	extensive	intensive	-

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For each set select the most abundant isotope or whether it cannot be determined.

boron-10 and boron-11

Choose one answer.

	A. boron-11
	B. boron-10
	C. can not be determined

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Nitrogen has two isotopes one of which is nitrogen-14 with a percent abundance of 99.634% and a mass of 14.003074 amu. What is the mass of nitrogen-15?

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Give the mass number for the species described. Hydrogen with no neutrons

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How many electrons are in the species listed?Chromium with a 3+ charge

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How many mol of carbon are in 31.5 g of carbon tetrachloride?

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What is the mass of oxygen in 5.97 g of iron(III) oxide?

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What is the total sample size (in grams) for a sample of magensium nitrate which contains 3.66 g of oxygen?

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What is the name of HClO3 (when this substance is in a water solution)?

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What is the sum of the stoichiometric coefficients when the reaction is balanced to lowest common denominator?

Fe2O3(s) + CO(g) --> Fe(s) + CO2(g)

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How many moles of oxygen react when 0.737 mol of ethanol (CH3CH2OH) are combusted in oxygen to produce carbon dioxide and water?

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What is the experimental yield (in grams) of the solid product when the percent yield is 82.4 % when 7.410 g of barium chloride reacts in solution with excess sodium phosphate?

BaCl2(aq) + Na3PO4(aq) --> Ba3(PO4)2(s) + NaCl(aq) [unbalanced]

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What is the percent yield of the solid product when 12.38 g of iron(III) nitrate reacts in solution with excess sodium phosphate and 5.336 g of the precipitate is experimentally obtained?

Fe(NO3)3(aq) + Na3PO4(aq) --> FePO4(s) + NaNO3(aq) [unbalanced]

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What is the limiting reactant when equal masses of iron(II) chloride and sodium phosphate react in solution?

Choose one answer.

	A. iron(II) phosphate
	B. sodium chloride
	C. iron(II) chloride
	D. sodium phosphate
	E. This reaction does not occur
	F. Cannot be determined without actual masses.C

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In the reaction of bromine with potassium iodide to produce potassium bromide and iodine, what is reduced and what is the reducing agent?

Choose one answer.

	A. bromine is reduced and potassium iodide is the reducing agent
	B. bromine is reduced and bromine is the reducing agent
	C. iodine is reduced and potassium iodide is the reducing agent
	D. iodine is reduced and bromine is the reducing agent
	E. potassium is reduced and potassium iodide is the reducing agent
	F. potassium is reduced and bromine is the reducing agent

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Which reactions are redox reactions?

Choose at least one answer.

	A. iron(III) oxide reacting with carbon monoxide to form liquid iron and carbon dioxide
	B. copper reacting with nitric acid to form nitrogen dioxide, water and copper(II) nitrate
	C. copper(II) nitrate reacting with potassium sulfide to form the precipitate copper(II) sulfide and aqueous potassium nitrate
	D. nitrous acid reacting with potassium hydroxide to form potassium nitrite and water
	E. ammonia reacting with hydrochloric acid to form ammonium chloride
	F. hydrogen and oxygen reacting to form water

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What is the concentration (in M) of the chloride ion when 17 mL of a 0.665 M solution of barium chloride is combined with 17.7 mL of a 0.547 M solution of aluminum chloride? Assume the volumes are additive.

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What is the concentration of the ammonium ion (in M) in a solution which contains 57 g ammonium sulfide in 721 mL of solution?

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What volume (in mL) of water must be added to a 1.52 M solution of sodium chloride to make a 48.4 mL of a 0.70215 M solution? Assume the volumes are additive.

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What is the experimental yield (in g of precipitate) when 16.4 mL of a 0.7 M solution of iron(III) chloride is combined with 17.3 mL of a 0.595 M solution of lead(II) nitrate at a 88.2% yield?

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What is the theoretical yield (in g of precipitate) when 15 mL of a 0.739 M solution of iron(III) chloride is combined with 17.2 mL of a 0.673 M solution of lead(II) nitrate?

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Under constant pressure, at what temperature (in K) will a balloon double in size when originally at 113.9oC?

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What is the density (in g/L) of nitric oxide (NO) at 327 K and under 1.221 atm of pressure?

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What is the molar mass of a gas which occupies 43 L at 120oC under 698 torr of pressure and has a mass of 24.8 grams?

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When 48.3 L of nitric oxide reacts with 31.1 L of oxygen at 313 K under a constant pressure of 1.458 atm, what is the theoretical yield (in g) of nitrogen dioxide?

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WhichÂ substance would most behave as an ideal gas at STP?

Choose one answer.

	A. N2
	B. H2O
	C. CH3OH
	D. HF

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Nitrogen and hydrogen react in the Haber process to form ammonia. All substances are in the gas phase. If 0.541 atm of nitrogen and 0.681 atm of hydrogen react, what is the partial pressure of ammonia (in mmHg) when this reaction goes 60.8 complete. The volume and temperature are constant.

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What is the root mean square speed (in m/s) of nitrogen at 16.3oC?

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When 10.33 g of neon is combined in a 20.9 L container at 112oC with 10.51 g of argon, what is the partial pressure (in mmHg) of argon?

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What is the final temperature (in oC) of a 35.3 g sample of graphite (specific heat = 0.720 J/(g K)) which absorbs 8.52 kJ of heat when it warms from 16.57oC?

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An 26.57 g sample of aluminum is placed on a 62.01 g sample of copper initially at 109.03oC. If the heat is only transferred between the metals (with no loss to the surroundings) and the final temperature of both metals is 35.64oC, what is the inital temperature (in oC) of aluminum?

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How much heat (in kJ) is evolved (under standard conditions) when 97.55 g of copper reacts to form copper(II) oxide?

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How much heat (in kJ) is needed when 96.81 g of water warms and boils from 40.15oC to 100oC?

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What is recorded as the final temperature (in oC) on a constant pressure calorimeter if 11.237 g of potassium hydroxide is dissolved in 34.516 mL of water originally at 21.846oC?

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What is the coefficient for nitrogen in the formation reaction for ammonia? Enter any fraction as a decimal.

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What is the enthalpy of formation of butane (C4H10) if the enthalpy of combustion for butane is -2876.9 kJ/mol (water is produced as a liquid)? Use the appendix in your textbook, do not enter units, and answer with 3 significant digits.

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In the photoelectric effect, above the threshhold frequency, the number of ejected electrons is proportional to

Choose one answer.

	A. the intensity of the incident light.
	B. the frequency of the incident light.
	C. the speed of the incident light.

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Which ion is paramagnetic in the ground state?

Choose one answer.

	A. Fe3+
	B. Al3+
	C. S2-
	D. Zn2+
	E. Ag+
	F. F-

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Which set(s) of quantum numbers is/are not possible for a ground state electron in zinc?

Choose at least one answer.

	A. (4, 1, 0, 1/2)
	B. (4, 0, 0, 1/2)
	C. (3, 2, -2, 1/2)
	D. (2, 0, 0, 1/2)
	E. (5, 0, 0, 1/2)
	F. (4, 2, 2, 1/2)

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How many values of l are possible when n = 4?

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What is the energy (in J) of a photon when an electron relaxes from n = 4 to n = 2 in a hydrogen atom?

Answer with no units, to 2 significant digits and using exponential notion as "1.0x10-10" entered as "1.0x10(-10)"

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Marks: 1

What ion(s) is/are not isoelectronic with a neon atom?

Choose at least one answer.

	A. the potassium ion
	B. the sodium ion
	C. the chloride ion
	D. the oxide ion
	E. the nitride ion
	F. the calcium ion

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Marks: 1

What is the periodic trend for atomic radii?

Choose one answer.

	A. decreasing right to left in a period, increasing bottom to top in a group
	B. increasing right to left in a period, increasing bottom to top in a group
	C. decreasing right to left in a period, decreasing bottom to top in a group
	D. increasing right to left in a period, decreasing bottom to top in a group

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Marks: 1

What is the periodic trend for first ionization energy?

Choose one answer.

	A. increasing right to left in a period, decreasing bottom to top in a group
	B. increasing right to left in a period, increasing bottom to top in a group
	C. decreasing right to left in a period, decreasing bottom to top in a group
	D. decreasing right to left in a period, increasing bottom to top in a group

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Which element exhibits the least metallic character?

Choose one answer.

	A. Be
	B. Ca
	C. Mg
	D. Ba

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Using the equation in your textbook (9.2, p. 291) as an approximation, which ionic compound will have the greatest lattice energy?

Choose one answer.

	A. LiF
	B. LiCl
	C. NaF
	D. NaCl

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How many lone pairs of electrons are on the central atom in xenon tetrafluoride?

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How many resonance structures does the nitrite ion have?

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What is the formal charge on nitrogen in the nitrite ion?

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Using the table of bond enthalpies in your textbook, what is the change in enthalpy (in kJ) when 1.61 mol of HCN molecules are broken into atoms?

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What is the carbon-oxygen bond length in the carbonate ion?

Choose one answer.

	A. between C-O and C=O
	B. two are C-O and one is C=O
	C. all are C-O
	D. all are C=O
	E. all are longer than C-O
	F. all are shorter than C=O
	G. two are C=O and one is C-O

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Which molecule has the greatest dipole moment?

Choose one answer.

	A. HF
	B. HCl
	C. HBr
	D. HI

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How many pi bonds are in one molecule of acetylene, HCCH?

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How many sigma bonds are in one molecule of dinitrogen monoxide?

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Using a MO diagram, how many antibonding electrons are in one molecule of nitrogen

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What is the hybridization on either central atom in acetylene, HCCH?

Enter your answer with no spaces and no superscripts, for example, sp2 is entered as "sp2".

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What is the hybridization on the central atom in formaldehyde, COH2?

Enter your answer with no spaces and no superscripts, for example, sp2 is entered as "sp2".

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What is the shape of iodine trichloride?

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At higher elevations, what is the effect the pressure on the boiling point of a substance?

Choose one answer.

	A. the boiling point is lowered because the external pressure is lower
	B. the boiling point is lowered because the external pressure is higher
	C. the boiling point is raised because the external pressure is lower
	D. the boiling point is raised because the external pressure is higher

Marks: 1

What type of bonding is present in a solid which is hard, has a high melting point, and is not conductive in the solid state?

Choose one answer.

	A. covalent
	B. ionic
	C. metallic
	D. molecular

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Marks: 1

What type(s) of intermolecular forces are present between hydrogen bromide and water?

Choose at least one answer.

	A. dipole-dipole
	B. dispersion
	C. dipole-induced dipole
	D. ion-induced dipole
	E. ion-dipole

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Marks: 1

What type(s) of intermolecular forces are present in the pure molecular substance of acetic acid?

Choose at least one answer.

	A. dispersion
	B. ionic
	C. dipole
	D. hydrogen bonding
	E. covalent bonding

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The density of an aqueous solution of nitric acid is 1.43 g/mL and the concentration is 3.19 M. What is the concentration of this solution in m?

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The density of an aqueous solution of sulfuric acid is 1.43 g/mL and the concentration is 2.9 M. What is the concentration of this solution in mole fraction?

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What is the density (in g/cm3) of a fictious elemental solid which packs in a body-centered cubic unit cell with an edge length of 331 pm and a molar mass of 178 g/mol?

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The vapor pressure of water at 45oC is 71.88 mmHg. What is the vapor pressure of a sugar (C12H22O11) solution made by dissolving 52.42 g of sugar in 94.99 g of water?

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What is the freezing point of water made by dissolving 17.86 g of sodium chloride in 92.98 g of water? The freezing-point depression constant of water is 1.86 oC/m.

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If the initial rate is 0.0581 M/s for a reaction with a rate law of rate = k[A]0[B], what is the value of the rate constant when the initial concentration of [A] is 0.0746 M and [B] is 0.0574 M?

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For a first order decay of [A], if 525 mg remains of an initial sample of 1.3079 g after 361 min, what is the half life (in minutes)?

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The decay of carbon-14 is first order with a half life is 5657 years. How much of 1.3449 g sample would remain after 9221 years?

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If the rate constant for a reaction at 65.26 oC is 0.466 s-1 and the activation energy is 24.80 kJ/mol, what is the rate constant at 133.0oC?

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For the reaction mechanism,

A + B --> C + D (slow)

A + D --> E + B (fast)

the rate determining step is

Choose one answer.

	a. unimolecular.
	b. bimolecular.
	c. termolecular.
	d. cannot be determined.

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For the reaction mechanism,

A + B --> C + D (slow)

A + D --> E + B (fast)

what is the catalyst?

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The reaction of A --> products is second order. Therefore, plotting what versus time will result in a straight line?

Choose one answer.

	a. [A]
	b. ln [A]
	c. 1/[A]
	d. [A]2

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Marks: 1

For which reaction is KC = [CO2]?

(Note: For all equilibrium problems, the single direction arrow should be a double arrow representing an equilibrium.)

Choose one answer.

	a. CaCO3(s) --> CaO(s) + CO2(g)
	b. C(s) + O2(g) --> CO2(g)
	c. CO2(g) + H2O(l) --> H2CO3(aq)
	d. CH4(g) + 2O2(g) --> CO2(g) + 2H2O(g)

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If the equilibrium constant for the reaction of 2A --> 2B is KC, what is the value for the equilibrium constant for the reaction of B --> A?

(Note: For all equilibrium problems, the single direction arrow should be a double arrow representing an equilibrium.)

Choose one answer.

	a. -2KC
	b. 1/KC
	c. (KC)1/2
	d. 1/2KC
	e. 1/(KC)1/2
	f. (KC)2
	g. 1/(KC)2
	h. 2KC

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Marks: 1

If the value of KC for the reaction:

2O3(g) --> 3O2(g) is 0.004082,

what is the value KP at a temperature of 25.55oC?

(Note: For all equilibrium problems, the single direction arrow should be a double arrow representing an equilibrium.)

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If Qc is less than Kc, then the reaction will

Choose one answer.

	a. shift to the right by increasing the concentration of the products.
	b. shift to the right by increasing the concentration of the reactants
	c. shift to the left by increasing the concentration of the products.
	d. shift to the left by increasing the concentration of the reactants.

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Marks: 1

The value of Kc for the reaction of dinitrogen tetroxide to make nitrogen dioxide is 0.8143. The concentration of nitrogen dioxide 1.1850 M with no dinitrogen tetroxide. What is the equilibrium concentration (in M) of nitrogen dioxide?

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Marks: 1

The value of Kc for the reaction of phosphorus pentachloride to make phosphorus trichloride and chlorine is 1.0950. The concentration of phosphorus pentachloride 1.38299 M with no products. What is the equilibrium concentration (in M) of chlorine?

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Marks: 1

What is the value of KP for the reaction of nitrogen and oxygen to make dinitrogen monoxide if the equilibrium partial pressures of nitrogen is 1.2799 atm, the partial pressure of oxygen is 1.0938 atm and the partial pressure of dinitrogen monoxide is 0.0345 atm?

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Marks: 1

For the reaction of 2N2(g) + O2(g) --> 2NO2(g), decreasing the temperature will cause the reaction to

(Note: For all equilibrium problems, the single direction arrow should be a double arrow representing an equilibrium.)

Choose one answer.

	a. shift to the right by increasing the concentration of the products.
	b. shift to the right by increasing the concentration of the reactants
	c. shift to the left by increasing the concentration of the products.
	d. shift to the left by increasing the concentration of the reactants.
	e. not change as the change in temperature will not affect the equilibrium.

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Marks: 1

For the reaction of CO2(g) + NO(g) --> NO2(g) + CO(g), if the pressure of the reaction vessel is increased by adding He(g), the equilibrium will be reestablished by the reaction

(Note: For all equilibrium problems, the single direction arrow should be a double arrow representing an equilibrium.)

Choose one answer.

	a. shifting to the right by increasing the concentration of the products.
	b. shifting to the right by increasing the concentration of the reactants
	c. shifting to the left by increasing the concentration of the products.
	d. shifting to the left by increasing the concentration of the reactants.
	e. not changing as the change in pressure will not affect the equilibrium.

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Marks: 1

Which set is not a conjugate acid/base pair?

Choose one answer.

	a. CH3COOH / CH3COO-
	b. HCN / CN-
	c. H2O / OH-
	d. H2SO4 / HSO3-

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Marks: 1

What is the pH of a 1x10-5 M aqueous solution of nitric acid?

Choose one answer.

	a. pH < 7
	b. pH = 7
	c. pH > 7
	d. Cannot be determined

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Marks: 1

What is the percent ionization of a 0.377 M aqueous solution of acetic acid? Ka (CH3COOH) = 1.8x10-5

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What is the pH of a 0.371 M aqueous solution of benzoic acid? Ka (C6H5COOH) = 6.5x10-5

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What is the pH of a 0.358 M aqueous solution of oxalic acid? Ka1 = 6.5x10-2; Ka2 = 6.1x10-5

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Which reaction corresponds to Ka2 for carbonic acid?

Choose one answer.

	a. H2CO3(aq) --> HCO3-(aq) + H+(aq)
	b. H2CO3(aq) --> CO32-(aq) + 2H+(aq)
	c. HCO3-(aq) --> CO32-(aq) + H+(aq)
	d. CO32-(aq) + 2H+(aq) --> H2CO3(aq)

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What is the pH of a 0.428 M aqueous solution of NaCN? Ka (HCN) = 4.9x10-10

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Aqueous ammonium nitrite will have a pH _____ 7. Enter either <, =, or >.

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What is the pH of an aqueous solution made by combining 39.62 mL of a 0.4701 M ammonium chloride with 36.24 mL of a 0.3369 M solution of ammonia to which 3.591 mL of a 0.0615 M solution of NaOH was added?

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What is the pH of an aqueous solution made by combining 39.58 mL of a 0.4135 M sodium formate with 37.13 mL of a 0.3650 M solution of formic acid?

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What is the pH of an aqueous solution made by combining 13.98 mL of a 0.1461 M hydrochloric acid with 45.04 mL of a 0.3087 M solution of ammonia?

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In a titration of 46.40 mL of 0.3259 M ammonia with 0.3259 M aqueous nitric acid, what is the pH of the solution when 46.40 mL of the acid have been added?

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In a titration of 39.69 mL of 0.3907 M nitrous acid with 0.3907 M aqueous sodium hydroxide, what is the pH of the solution when 39.69 mL of the base have been added?

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What is the pKa of HNO2? _____ Ka = 4.5x10-4. Use three digits for your answer.

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Which base has the lowest pKa?

Choose one answer.

	a. CH3NH2
	b. C2H5NH2
	c. C6H5NH2
	d. NH3

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100

Marks: 1

In order to selectively precipitate barium ions from calcuim ions, what could you add?

Choose one answer.

	a. either sodium carbonate or sodium fluoride
	b. sodium fluoride but not sodium carbonate
	c. sodium carbonate but not sodium fluoride
	d. neither sodium carbonate nor sodium fluoride

101

Marks: 1

What is the concentration of the calcium ion in a saturated solution of calcium fluoride that also contains 0.0100 M sodium fluoride

Choose one answer.

	a. [Ca2+] greater than [F-]
	b. [Ca2+] equal to [F-]
	c. [Ca2+] less than [F-]
	d. Cannot be determined without volumes

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102

Marks: 1

What is the molar solubility of silver sulfide? _____ Enter your answer with 3 significant digits with no units and the format of "1.00x10(-4)" for 1.00x10-4.

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103

Marks: 1

What kind of a solution do you have when you mix 10.0 mL of a 1x10-4 M silver nitrate with 10.0 mL of a 1x10-8 M sodium chloride?

Choose one answer.

	a. There is no precipitate and the solution is saturated.
	b. There is no precipitate and the solution is unsaturated.
	c. There is a precipitate and the solution is saturated.
	d. There is a precipitate and the solution is unsaturated.

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104

Marks: 1

Using Appendix 1 in your textbook, what is the standard change in entropy (in J/K) at 25oC of the reaction:

2CO(g) + O2(g) --> 2CO2(g)?

Answer:

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105

Marks: 1

What is the sign on the change in entropy for the process: 2N2(g) + O2(g)--> 2N2O(g)

Choose one answer.

	a. entropy is increasing
	b. entropy is unchanged
	c. entropy is decreasing
	d. entropy cannot be approximated

Question

106

Marks: 1

What is the order of the lowest entropy (1 = lowest) to highest entropy (3 = highest)?

Br2(g)

Choose...	2 = moderate	3 = highest	1 = lowest
Cl2(g)	Choose...	2 = moderate	3 = highest	1 = lowest
F2(g)	Choose...	2 = moderate	3 = highest	1 = lowest

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107

Marks: 1

Which describes an endothermic system in which the entropy of the universe is increasing (spontaneous)?

Choose one answer.

	a. Enthalpy of the surroundings decreases and the entropy of the system decreases
	b. Enthalpy of the surroundings decreases and the entropy of the system increases
	c. Enthalpy of the surroundings increases and the entropy of the system decreases
	d. Enthalpy of the surroundings increases and the entropy of the system increases

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108

Marks: 1

Using Appendix 2 in your textbook, at what temperature (in K) will the reaction, 2H2O(l) --> 2H2(g) + O2(g), change in spontaneity?

Assume standard change in enthalpy and standard change in entropy do not change with temperature.

Answer:

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109

Marks: 1

Using Appendix 2 in your textbook, what is the value for the standard change in Gibbs free energy (in kJ) at 25oC of the reaction:

2NO(g) + N2(g) --> 2N2O(g)?

Answer:

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110

Marks: 1

Which combination will result in a system that is spontaneous at high temperatures only?

Choose one answer.

	a. ΔHsys< 0 and ΔSsys< 0
	b. ΔHsys< 0 and ΔSsys > 0
	c. ΔHsys > 0 and ΔSsys< 0
	d. ΔHsys > 0 and ΔSsys > 0

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111

Marks: 1

Given the Ka of benzoic acid from Chapter 16 in your textbook, what is the value of change in Gibbs free energy (in kJ/mol) at 25oC for this process?

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112

Marks: 1

How many electrons are transferred in the redox reaction taking place in acidic solution:

Sn2+(aq) + Cr2O72-(aq) --> Cr3+(aq) + Sn4+(aq)?

Answer:

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113

Marks: 1

What is the stoichiometric coefficient for the hydroxide ion in the balanced redox reaction of:

In+(aq) + ClO-(aq) --> Cl-(aq) + In3+(aq) when balanced in basic solution?

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114

A galvanic cell consists of a iron electrode in 1.0 M Fe(NO3)2 and a copper electrode in 1.0 M Cu(NO3)2. What is the standard cell potential (emf, in V) of this cell at 25oC?

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115

For a galvanic cell, Eo equals

Choose one answer.

	a. Eored - Eoox, where each value is the standard reduction potential
	b. Eoox - Eored, where each value is the standard reduction potential
	c. Eored + Eoox, where each value is the standard reduction potential
	d. Eoox * Eored, where each value is the standard reduction potential

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116

What direction do the electrons and the cations flow in a galvanic cell?

Choose one answer.

	a. the electrons flow from the cathode to the anode and the cations flow from the oxidation half-reaction to the reduction half-reaction to charge balance
	b. the electrons flow from the anode to the cathode and the cations flow from the oxidation half-reaction to the reduction half-reaction to charge balance
	c. the electrons flow from the cathode to the anode and the cations flow from the reduction half-reaction to the oxidation half-reaction to charge balance
	d. the electrons flow from the anode to the cathode and the cations flow from the reduction half-reaction to the oxidation half-reaction to charge balance

Question

117

What is the standard Gibbs free energy (in kJ) of this cell at 25oC?

Cu |Cu2+ (1.0 M) ǁ Br2 |Br- (1 M)

Answer:

Question

118

A galvanic cell consists of a lead electrode in 0.0254 M Pb(NO3)2 and a aluminum electrode in 0.281 M Al(NO3)3. What is the cell potential (emf, in V) of this cell at 25oC?

Answer:

Question

119

What is the difference between a primary and a secondary or storage (a rechargeable) battery?

Choose one answer.

	a. a primary battery is a galvanic cell and a secondary battery is not
	b. a secondary battery is a galvanic cell and a primary battery is not
	c. the products of the oxidation-reduction are deposited directly on the electrode surface for a secondary battery but not for a primary battery
	d. the oxidation-reduction process for a secondary battery is reversible with the application of an external source while a primary battery is not

Question

120

What mass (in g) of aluminum can be electroplated when 0.763 amps are used for 1.394 hours using a solution of aluminum nitrate?

Answer: