Chem 111A final

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?

0.0493 mol

What is the molarity of a potassium triiodide solution, KI3(aq), if 30.00 mL of the solution is required to completely react with 25.00 mL of a 0. 200 M thiosulfate solution, K2S2O3(aq)? The chemical equation for the reaction is 2 S2O32- (aq) + I3-(aq) → S4O62-(aq) + 3 I-(aq).

0.167 M

The titration of 25.0 mL of an unknown concentration H2SO4 solution requires 83.6 mL of 0.12 M LiOH solution. What is the concentration of the H2SO4 solution (in M)?

0.20 M

Two samples of calcium fluoride are decomposed into their constituent elements. The first sample produced 0.154 g of calcium and 0.146 g of fluorine. If the second sample produced 294 mg of fluorine, how many g of calcium were formed?

0.309 g

What is the mole fraction of oxygen in a gas mixture that is 37% oxygen and 63% nitrogen by volume?

0.37

Silver ions can be precipitated from aqueous solutions by the addition of aqueous chloride: Ag+ (aq) + Cl- (aq) → AgCl (s) Silver chloride is virtually insoluble in water so that the reaction appears to go to completion. How many grams of solid NaCl must be added to 25.0 mL of 0.366 M AgNO3 solution to completely precipitate the silver?

0.535 g

A solution is prepared by adding 1.60 g of solid NaCl to 50.0 mL of 0.100 M CaCl2. What is the molarity of chloride ion in the final solution? Assume that the volume of the final solution is 50.0 mL.

0.747

Draw the best Lewis structure for CH3+1. What is the formal charge on the C?

1

How many grams of NaHCO3 (baking soda) would you need to neutralize 500 mL of battery acid (H2SO4) that has been spilled on your garage floor? Assume that the concentration of the battery acid is 12 molar.

1,008 grams

How many moles of CuO can be produced from 0.900 mol of Cu2O in the following reaction? 2 Cu2O(s) + O2(g) → 4 CuO(s)

1.80 mol

Consider the following balanced reaction. How many grams of water are required to form 75.9 g of HNO3? Assume that there is excess NO2 present. The molar masses are as follows: H2O = 18.02 g/mol, HNO3 = 63.02 g/mol. 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

10.9 g H₂O

Calculate the wavelength of light associated with the transition from n=1 to n=3 in the hydrogen atom.

103 nm

What total energy (in kJ) is contained in 1.0 mol of photons, all with a frequency of 2.75 × 1014 Hz?

110 kJ

What is the percent yield of water if 0.90 g of water is obtained when 29.0 g of butane is burned in excess oxygen?

2.0%

At 20°C, a 0.376 M aqueous solution of ammonium chloride has a density of 1.0045 g/mL. What is the mass % of ammonium chloride in the solution? The formula weight of NH4Cl is 53.50 g/mol.

2.00

The Henry's law constant for helium gas in water at 30°C is 3.70 × 10-4 M/atm. When the partial pressure of helium above a sample of water is 0.650 atm, the concentration of helium in the water is __________ M.

2.41 x 10⁻⁴

How many chloride ions are present in 65.5 mL of 0.210 M AlCl3 solution?

2.48 x 10²² chloride ions

How many liters of air are in a room that measures 10.0 ft × 11.0 ft and has an 8.00 ft ceiling? 1 in. = 2.54 cm (exactly); 1 L = 103 cm3

2.49 x 10⁴

Calcium phosphate reacts with sulfuric acid to form calcium sulfate and phosphoric acid. What is the coefficient for sulfuric acid when the equation is balanced using the lowest, whole-numbered coefficients?

3

How many of the following molecules have sp3d2 hybridization on the central atom? SeCl6 XeF4 IF5 AsCl5

3

What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest, whole-number coefficients? _____ C2H6O (l) + _____ O2(g) → _____ CO2(g) + _____ H2O(l)

3

How much energy (in kJ) is required to ionize 2.78 moles of hydrogen atoms?

3.65 x 10³ kJ

Electromagnetic radiation with a wavelength of 525 nm appears as green light to the human eye. The energy of one photon of this light is __________ J.

3.79 x 10⁻¹⁹

How many grams of calcium hydride are required to produce 4.56 L of hydrogen gas at 25.0°C and 0.975 atm pressure according to the chemical equation shown below? CaH2(s) + 2 H2O(l) → Ca(OH)2(aq) + 2 H2(g)

3.82 g

Using the following equation for the combustion of octane, calculate the amount of grams of carbon dioxide formed from 100.0 g of octane. The molar mass of octane is 114.33 g/mole. The molar mass of carbon dioxide is 44.0095 g/mole.

307.9 g

A piece of iron (mass = 25.0 g) at 398 K is placed in a styrofoam coffee cup containing 25.0 mL of water at 298 K. Assuming that no heat is lost to the cup or the surroundings, what will the final temperature of the water be? The specific heat capacity of iron = 0.449 J/g°C and water = 4.18 J/g°C.

308 K

The recommended adult dose of Elixophyllin, a drug used to treat asthma, is 6.00 mg/kg of body mass. Calculate the dose in milligrams for a 115-lb person. 1 lb = 453.59 g.

313

What pressure would a gas mixture in a 10.0 L tank exert if it were composed of 48.5 g He and 94.6 g CO2 at 398 K?

46.6 atm

How many grams of oxygen are formed when 6.21 moles of KOH are formed? 4 KO(s) + 2 H2O(l) → 4 KOH(s) + O2(g)

49.7 g O₂

Choose the compound below that should have the lowest melting point according to the ionic bonding model.

CsI

Place the following in order of decreasing X-A-X bond angle, where A represents the central atom and X represents the outer atoms in each molecule. CS2 CF4 SCl2

Cs₂> Cf₄> SCl₂

In the following reaction; Cu(s) + 4 HNO3(aq) → Cu(NO3)2(aq) + 2 H2O(l)

Cu

A solution is prepared by adding 30.00 g of lactose (milk sugar) to 110.0 g of water at 55°C. The partial pressure of water above the solution is __________ torr. The vapor pressure of pure water at 55°C is 118.0 torr. The MW of lactose is 342.3 g/mol.

116.3

If the percent yield for the following reaction is 65.0%, how many grams of KClO3 are needed to produce 32.0 g of O2? 2 KClO3(s) → 2 KCl(s) + 3 O2(g)

126 g

Determine the electron geometry (eg), molecular geometry(mg) and polarity of XeO3.

eg= tetrahedral, mg= trigonal pyramidal, polar

Determine the electron geometry (eg) and molecular geometry (mg) of ICl2⁻.

eg= trigonal bipyramidal, mg= linear

At a given temperature the vapor pressures of benzene and toluene are 183 mm Hg and 59.2 mm Hg, respectively. Calculate the total vapor pressure over a solution of benzene and toluene with Xbenzene = 0. 580

131 mm Hg

What is the total volume of the mixture of hydrogen gas and oxygen gas can be obtained from the electrolysis of 110.0 grams of water at 25.0°C and 1.00 atm pressure according to the chemical equation shown below?

149 L

Balance the chemical equation given below, and determine the number of milliliters of 0.00300 M phosphoric acid required to neutralize 45.00 mL of 0.00150 M calcium hydroxide. ______ Ca(OH)2(aq) + ______ H3PO4(aq) → ______ Ca3(PO4)2(aq) + ______ H2O(l)

15.0 mL

According to the following thermochemical equation, what mass of HF (in g) must react in order to produce 345 kJ of energy? Assume excess SiO2.

150. g

Consider the phase diagram below. If the dashed line at 1 atm of pressure is followed from 100 to 500°C, what phase changes will occur (in order of increasing temperature)?

fusion, followed by vaporization

Solutions having osmotic pressures less than those of body fluids are called __________.

hypo osmotic

According to the following reaction, what amount of Al2S3 remains when 20.00 g of Al2S3 and 2.00 g of H2O are reacted? A few of the molar masses are as follows: Al2S3 = 150.17 g/mol, H2O = 18.02 g/mol. Al2S3(s) + 6 H2O(l) → 2 Al(OH)3(s) + 3 H2S(g)

17.22 g

How much heat is absorbed when 45.00 g of C(s) reacts in the presence of excess SO2(g) to produce CS2(l) and CO(g) according to the following chemical equation?

179.8 kJ

How many liters of O2 gas at 25°C and 1.00 atm pressure are needed to react with 60.25 grams of potassium hydride according to the chemical equation shown below?

18.4 L

The estimated costs for remodelling the interior of an apartment are: three 1-gallon cans of paint at $13.22 each , two paint brushes at $9.53 each , and $135 for a helper. The total estimated cost with the appropriate significant figures is

194

Give the complete electronic configuration for S2-.

1s2 2s2 2p6 3s2 3p6

How many of the following compounds are insoluble in water? KC2H3O2 CaSO4 SrS AlPO4

2

Which one of the following has a definite shape and volume?

solid

Draw the Lewis structure for OF2. What is the hybridization on the O atom?

sp3

Draw the Lewis structure for BrCl3. What is the hybridization on the Br atom?

sp3d

The probability area that best represents the shape of one of the atomic 3d orbitals is.

table, big rock, clock

Gas is sold for $1.399 per liter in Toronto, Canada. Your car needs 12.00 gallons. How much will your credit card be charged in Canadian dollars?

$63.54

Which of the following compounds will be most soluble in pentane (C5H12)?

(C₆H₆)

What is the oxidation number of arsenic in AsO4-3(aq)?

+ 5

The combustion of titanium with oxygen produces titanium dioxide: Ti (s) + O2 (g) → TiO2 (s) When 2.060 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter increases from 25.00°C to 91.60°C. In a separate experiment, the heat capacity of the calorimeter is measured to be 9.84 kJ/K. The heat of reaction for the combustion of a mole of Ti in this calorimeter is __________ kJ/mol.

-1.52 x 10⁴

The osmotic pressure of a solution formed by dissolving 25.0 mg of aspirin (C9H8O4) in 0.250 L of water at 25°C is __________ atm.

0.0136

A solution is prepared by dissolving 7.00 g of glycerin (C3H8O3) in 201 g of ethanol (C2H5OH). The freezing point of the solution is __________°C. The freezing point of pure ethanol is -114.6 °C at 1 atm. The molal-freezing-point-depression constant (Kf) for ethanol is 1.88 °C/m. The molar masses of glycerin and of ethanol are 92.1 g/mol and 46.1 g/mol, respectively.

-115.4

Use the bond energies provided to estimate ΔH°rxn for the reaction below. C2H4(g) + H2(g) → C2H6(g) ΔH°rxn = ?

-128 kJ

A 4.98 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 4.25 kJ/°C. If the temperature rose from 29.5°C to 69.8°C, determine the value of ΔH°comb for aniline.

-3.20 x 10³ kJ/ mol

When 1.50 g of Ba(s) is added to 100.00 g of water in a container open to the atmosphere, the reaction shown below occurs and the temperature of the resulting solution rises from 22.00°C to 33.10°C. If the specific heat of the solution is 4.18 J/(g ∙ °C), calculate ΔH for the reaction, as written.

-431 kJ

A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.00°C and the temperature of the resulting solution was recorded as 37.00°C, determine the ΔH°rxn (in units of kJ/mol NaOH) for the neutralization reaction between aqueous NaOH and HCl. Assume 1) that no heat is lost to the calorimeter or the surroundings, and 2) that the density and the heat capacity of the resulting solution are the same as water.

-55.7 kJ/ mol NaOH

A 4.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

1.05 atm

The common isotopes of carbon are 12C and 13C. The average mass of carbon is 12.01115 amu. What is the abundance of the 13C isotope?

1.115 %

How many molecules of butane are contained in 25.0 mL of butane? The density of butane is 0.6011 g/mL and the molar mass is 58.12 g/mol

1.56 × 1023 molecules butane

Balance the chemical equation given below, and determine the number of moles of iodine that reacts with 30.0 g of aluminum. ________ Al(s) + ________ I2(s) → ________ Al2I6(s)

1.67 mol

A syringe contains 589 mL of CO at 325 K and 1.2 atm pressure. A second syringe contains 473 mL of N2 at 298 K and 2.6 atm. What is the final pressure if the contents of these two syringes are injected into a 1.00 L container at STP?

1.7 atm

How many molecules of XeF6 are formed from 12.9 L of F2 (at 298 K and 2.60 atm) according to the following reaction? Assume that there is excess Xe. Xe(g) + 3 F2(g) → XeF6(g)

2.75 x 10²³ molecules XeF₆

A 150.0 mL sample of an aqueous solution at 25°C contains 15.2 mg of an unknown nonelectrolyte compound. If the solution has an osmotic pressure of 8.44 torr, what is the molar mass of the unknown compound?

223 g/ mol

Give the percent yield when 28.16 g of CO2 are formed from the reaction of 8.000 moles of C8H18 with 4.000 moles of O2. 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

25.00%

What volume of 0.305 M AgNO3 is required to react exactly with 155.0 mL of 0.274 M Na2SO4 solution? Hint: You will want to write a balanced reaction.

278 mL

How much energy must be removed from a 94.4 g sample of benzene (molar mass= 78.11 g/mol) at 322.0 K to solidify the sample and lower the temperature to 205.0 K? The following physical data may be useful.

29.4 kJ

Determine the end (final) value of n in a hydrogen atom transition, if the electron starts in n = 1 and the atom absorbs a photon of light with an energy of 2.044 × 10-18 J.

4

A sample of air from a home is found to contain 6.2 ppm of carbon monoxide. This means that if the total pressure is 695 torr, then the partial pressure of CO is __________ torr.

4.3 x 10⁻³

Carbonic acid can form water and carbon dioxide upon heating. How much carbon dioxide is formed from 6.20 g of carbonic acid? H2CO3 → H2O + CO2

4.40 g

At 20°C, an aqueous solution that is 24.0% by mass in ammonium chloride has a density of 1.0674 g/mL. What is the molarity of ammonium chloride in the solution? The formula weight of NH4Cl is 53.50 g/mol.

4.79

The mole fraction of oxygen in dry air near sea level is 0.20948. The concentration of oxygen is __________ molecules per liter, assuming an atmospheric pressure of 739 torr and a temperature of 29.5°C.

4.93 x 10²¹

How many photons are contained in a flash of green light (525 nm) that contains 189 kJ of energy?

4.99 x 1023 photons

A sample of N2 effuses in 255 s. How long will the same size sample of Cl2 take to effuse?

406 s

A solution of LiCl in water has XLiCl = 0.0 900. What is the molality?

5.49 m LiCl

Determine the total volume of all gases (at STP) formed when 50.0 mL of TNT (C3H5(NO3)3 , d = 1.60 g/mL, molar mass = 227.10 g/mol) reacts according to the following reaction. 4 C3H5(NO3)3(l) → 6 N2(g) + O2(g) + 12 CO2(g) + 10 H2O(g)

57.2 L

How many grams of H2 gas can be produced by the reaction of 54.0 grams of Al(s) with an excess of dilute hydrochloric acid in the reaction shown below? 2 Al(s) + 6 HCl(aq) → 2 AlCl3(aq) + 3 H2(g)

6.05 g

Calculate the mass (in ng) of 2.33 x 1020 atoms of oxygen.

6.19 × 10⁶ ng

A sample of gas initially has a volume of 859 mL at 565 K and 2.20 atm. What pressure will the sample have if the volume changes to 268 mL while the temperature is increased to 815 K?

6.53 atm

Ethanol (C2H5OH) melts at -114°C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/gK and 2.3 J/gK, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C?

6.91 kJ

How many SO3 ions are contained in 99.6 mg of Na2SO3? The molar mass of Na2SO3 is 126.05 g/mol.

9.52 × 1020 SO3 ions

How many molecules of H2S are required to form 79.0 g of sulfur according to the following reaction? Assume excess SO2. 2 H2S(g) + SO2(g) → 3 S(s) + 2H2O(l)

9.89 x 10²³ molecules H₂S

Write a balanced equation to show the reaction of aqueous aluminum acetate with aqueous ammonium phosphate to form solid aluminum phosphate and aqueous ammonium acetate.

Al(C2H3O2)3 (aq) + (NH4)3PO4 (aq) → AlPO4 (s) + 3 NH4C2H3O2 (aq)

Place the following substances in order of decreasing boiling point. He Ar H2

Ar > He> H₂

Choose the compound below that contains at least one polar covalent bond, but is nonpolar.

AsCl₅

Determine the molecular formula for a compound that is 70.79% carbon, 8.91% hydrogen, 4.59% nitrogen, and 15.72% oxygen

C18H27NO3

Combustion analysis of 1.200 g of an unknown compound containing carbon, hydrogen, and oxygen produced 2.086 g of CO2 and 1.134 g of H2O. What is the empirical formula of the compound?

C₃H₈O₂

Use the molecular orbital diagram shown to determine which of the following are paramagnetic.

F₂²⁺

Two students, Garrison and Isabella, determined the mass of an object on two different balances. The accepted mass of the object was 2.355 g. Garrison obtained values of 2.531 g, 2.537 g, 2.535 g and 2.533 g. Isabella obtained values of 2.350 g, 2.404 g, 2.296 g and 2.370 g. Which statement best describes the results that were obtained by Garrison and Isabella?

Isabella obtained the better accuracy

Determine the limiting reactant (LR) and the mass (in g) of nitrogen that can be formed from 50.0 g N2O4 and 45.0 g N2H4. Some possibly useful molar masses are as follows: N2O4 = 92.02 g/mol, N2H4 = 32.05 g/mol. N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g)

LR= N₂O₄, 45.7 g N₂ formed

Place the following in order of decreasing magnitude of lattice energy. K2O Rb2S Li2O

Li₂O> K₂O> Rb₂S

A compound is found to be 30.45% N and 69.55 % O by mass. If 1.63 g of this compound occupy 389 mL at 0.00°C and 775 mm Hg, what is the molecular formula of the compound?

N₂O₄

Place the following substances in order of decreasing vapor pressure at a given temperature. BeF2 CH3OH OF2

OF₂> CH₃OH> BeF₂

Given the lead-acid battery reaction: Pb + PbO2 + H2SO4 Discharge → Charge<-- 2PbSO4 + 2H2O Which species is oxidized during battery discharge?

Pb

What do the following have in common? 20Ne 19F- 24Mg2+

They are isoelectronic with each other.

Choose the ground state electron configuration for Zr 2⁺

[Kr] 4d2

Identify the species that has the smallest radius

cation

The normal boiling point for H2Se is higher than the normal boiling point for H2S . This can be explained by

larger dispersion forces for H₂Se

Give the set of four quantum numbers that could represent the electron gained to form the Br ION from the Br atom.

n=4, l=0, ml= 1, ms= +1/2

Each of the following sets of quantum numbers is supposed to specify an orbital. Choose the one set of quantum numbers that does not contain an error.

n=5, l=3, ml= -3

When 10.00 moles of H2(g) reacts with 5.000 mol of O2(g) to form 10.00 mol of H2O(l) at 25°C and a constant pressure of 1.00 atm. If 683.0 kJ of heat are released during this reaction, and PΔV is equal to - 37.00 kJ, then

ΔH° = - 683.0 kJ and ΔE° = - 720.0 kJ

Choose the valence orbital diagram that represents the ground state of Sr 2⁺.

↑↓ ↑↓↑↓↑↓ 4s 4p