Questions and Answers of Chemistry An Atoms First Approach

What will be the effect on the volume of an ideal gas if the pressure is doubled and the absolute temperature is halved?
A container is filled with an ideal gas to a pressure of 11.0 atm at 0°C. a. What will be the pressure in the container if it is heated to 45°C? b. At what temperature would the pressure be 6.50
Consider the following reaction:It takes 2.00 L of pure oxygen gas at STP to react completely with a certain sample of aluminum. What is the mass of aluminum reacted? 4Al(s) + 30₂(g) - 2Al₂O3(s)
Which of the following statements is(are) true? a. If the number of moles of a gas is doubled, the volume will double, assuming the pressure and temperature of the gas remain constant. b. If the
A piece of solid carbon dioxide, with a mass of 7.8 g, is placed in a 4.0-L otherwise empty container at 27°C. What is the pressure in the container after all the carbon dioxide vaporizes? If 7.8 g
In the diagram below, which lines represent the hydrogen bonding? a. The dotted lines between the hydrogen atoms of one water molecule and the oxygen atoms of a different water molecule b. The
Refer to Fig. 9.14. Why doesn’t temperature increase continuously over time? That is, why does the temperature stay constant for periods of time?Fig. 9.14. Temperature
A 20.0-L nickel container was charged with 0.859 atm of xenon gas and 1.37 atm of fluorine gas at 400°C. The xenon and fluorine react to form xenon tetrafluoride. What mass of xenon tetrafluoride
Use the kinetic molecular theory to explain why a liquid gets cooler as it evaporates from an insulated container.
Silicon carbide (SiC) is an extremely hard substance that acts as an electrical insulator. Propose a structure for SiC.
What type of solid will each of the following substances form? a. diamond b. PH3 c. H₂ d. Mg e. KCI f. quartz g. NH4NO3 h. SF₂ i. Ar j. Cu k. C6H12O6
Consider Fig. 10.9. According to the caption and picture, water seems to go from one beaker to another.Fig. 10.9a. Explain why this occurs. b. The explanation in the text uses terms such as vapor
Explain how doping silicon with either phosphorus or gallium increases the electrical conductivity over that of pure silicon.
Define the terms in Raoult’s law. Fig. 10.9 illustrates the net transfer of water molecules from pure water to an aqueous solution of a nonvolatile solute. Explain why eventually all of the water
Some ionic compounds contain a mixture of different charged cations. For example, wüstite is an oxide that contains both Fe2+ and Fe3+ cations and has a formula of Fe0.950O1.00. Calculate the
Given the following electrostatic potential diagrams, comment on the expected solubility of CH4 in water and NH3 in water. н N H Н H Н Н Н с Н Н
In terms of Raoult’s law, distinguish between an ideal liquid–liquid solution and a nonideal liquid–liquid solution. If a solution is ideal, what is true about ΔHsoln, ΔT for the solution
Rubbing alcohol contains 585 g isopropanol (C3H7OH) per liter (aqueous solution). Calculate the molarity.
The lattice energy for an ionic compound is the enthalpy change for the process M+(g) + X-(g) → MX(s). For NaI, the lattice energy process is:If the enthalpy of hydration of NaI is -694 kJ/mol,
Which solvent, water or hexane (C6H14), would you choose to dissolve each of the following?a. Cu(NO3)2 b. CS2 c. CH3OHd. CH3(CH2)16CH2OH e. HCl f. C6H6
The vapor pressure of a solution containing 53.6 g glycerin (C3H8O3) in 133.7 g ethanol (C2H5OH) is 113 torr at 40°C. Calculate the vapor pressure of pure ethanol at 40°C assuming that glycerin is
At a certain temperature, the vapor pressure of pure benzene (C6H6) is 0.930 atm. A solution was prepared by dissolving 10.0 g of a nondissociating, nonvolatile solute in 78.11 g of benzene at that
A solution of sodium chloride in water has a vapor pressure of 19.6 torr at 25°C. What is the mole fraction of solute particles in this solution? What would be the vapor pressure of this solution at
Pentane (C5H12) and hexane (C6H14) form an ideal solution. At 25°C the vapor pressures of pentane and hexane are 511 and 150. torr, respectively. A solution is prepared by mixing 25 mL pentane
A solution is prepared by mixing 0.0300 mole of CH2Cl2 and 0.0500 mole of CH2Br2 at 25°C. Assuming the solution is ideal, calculate the composition of the vapor (in terms of mole fractions) at
What is the composition of a methanol (CH3OH)–propanol (CH3CH2CH2OH) solution that has a vapor pressure of 174 torr at 40°C? At 40°C, the vapor pressures of pure methanol and pure propanol are
Benzene and toluene form an ideal solution. Consider a solution of benzene and toluene prepared at 25°C. Assuming the mole fractions of benzene and toluene in the vapor phase are equal, calculate
Calculate the freezing point and boiling point of an antifreeze solution that is 50.0% by mass of ethylene glycol (HOCH2CH2OH) in water. Ethylene glycol is a nonelectrolyte.
A solution is prepared by dissolving 52.3 g cesium chloride in 60.0 g water. The volume of the solution is 63.3 mL. Calculate the mass percent, molarity, molality, and mole fraction of the CsCl
A solution is prepared by mixing 1.000 mole of methanol (CH3OH) and 3.18 moles of propanol (CH3CH2CH2OH). What is the composition of the vapor (in mole fractions) at 40°C? At 40°C, the vapor
An unknown compound contains only carbon, hydrogen, and oxygen. Combustion analysis of the compound gives mass percents of 31.57% C and 5.30% H. The molar mass is determined by measuring the
On Easter Sunday, April 3, 1983, nitric acid spilled from a tank car near downtown Denver, Colorado. The spill was neutralized with sodium carbonate: a. Calculate DH8 for this reaction.
The standard enthalpy of formation for NO(g) is 90. kJ/mol. Use this and the values for the O = O and N ≡ N bond energies to estimate the bond strength in NO.
When a gas expands, what is the sign of w? Why? When a gas contracts, what is the sign of w? Why? What are the signs of q and w for the process of boiling water?
What is Hess’s law? When a reaction is reversed, what happens to the sign and magnitude of ΔH for that reversed reaction? When the coefficients in a balanced reaction are multiplied by a factor n,
The bond energy for a C-H bond is about 413 kJ/mol in CH4 but 380 kJ/mol in CHBr3. Although these values are relatively close in magnitude, they are different. Explain why they are different. Does
How is average bond strength related to relative potential energies of the reactants and the products?
Which has the greater kinetic energy, an object with a mass of 2.0 kg and a velocity of 1.0 m/s or an object with a mass of 1.0 kg and a velocity of 2.0 m/s?
A gas absorbs 45 kJ of heat and does 29 kJ of work. Calculate ΔE.
A system releases 125 kJ of heat while 104 kJ of work is done on it. Calculate ΔE.
If the internal energy of a thermodynamic system is increased by 300. J while 75 J of expansion work is done, how much heat was transferred and in which direction, to or from the system?
The reactionis the last step in the commercial production of sulfuric acid. The enthalpy change for this reaction is -227 kJ. In designing a sulfuric acid plant, is it necessary to provide for
Are the following processes exothermic or endothermic? a. When solid KBr is dissolved in water, the solution gets colder. b. Natural gas (CH4) is burned in a furnace. c. When concentrated H2SO4 is
Are the following processes exothermic or endothermic? a. the combustion of gasoline in a car engine b. water condensing on a cold pipe c. CO₂ (s)- → CO₂(g) d. F₂(g) →→→2F(g)
A 5.00-g sample of one of the substances listed in Table 7.1 was heated from 25.2°C to 55.1°C, requiring 133 J to do so. Which substance was it?Table 7.1
In a coffee-cup calorimeter, 100.0 mL of 1.0 M NaOH and 100.0 mL of 1.0 M HCl are mixed. Both solutions were originally at 24.6°C. After the reaction, the final temperature is 31.3°C. Assuming that
The enthalpy of combustion of solid carbon to form carbon dioxide is 2393.7 kJ/mol carbon, and the enthalpy of combustion of carbon monoxide to form carbon dioxide is 2283.3 kJ/mol CO. Use these data
Write reactions for which the enthalpy change will be a. AH for solid aluminum oxide. b. the standard enthalpy of combustion of liquid ethanol, C₂H₂OH(I). c. the standard enthalpy of
Water gas is produced from the reaction of steam with coal:Assuming that coal is pure graphite, calculate ΔH° for this reaction. C(s) + H₂O(g) →→→ H₂(g) + CO(g)
Consider the following equations:Suppose the first equation is reversed and multiplied by 1/6, the second and third equations are divided by 2, and the three adjusted equations are added. What is the
Which of the following substances have an enthalpy of formation equal to zero?a. Cl2(g) b. H2(g) c. N2(l) d. Cl(g)
Quinone is an important type of molecule that is involved in photosynthesis. The transport of electrons mediated by quinone in certain enzymes allows plants to take water, carbon dioxide, and the
Which of the following pairs of compounds have the same empirical formula? a. acetylene, C₂H₂, and benzene, C6H₁ b. ethane, C₂H6, and butane, C4H10 c. nitrogen dioxide, NO2, and dinitrogen
An element “X” has five major isotopes, which are listed below along with their abundances. What is the element? Isotope 46X 47X 48X 49X 50X Percent
What mass of silver chloride can be prepared by the reaction of 100.0 mL of 0.20 M silver nitrate with 100.0 mL of 0.15 M calcium chloride? Calculate the concentrations of each ion remaining in
Nitrogen gas (N2) and hydrogen gas (H2) react to form ammonia gas (NH3).Assuming the reaction goes to completion, draw a representation of the product mixture. Explain how you arrived at this
For the preceding question, which of the following equations best represents the reaction? 4NH3 + 4N₂ a. 6N₂ + 6H₂ b. N₂ + H₂NH3 c. N + 3H NH3 d. N₂ + 3H₂ →→→ 2NH3 e. 2N₂ +
What is the difference between the empirical and molecular formulas of a compound? Can they ever be the same? Explain.
Can the subscripts in a chemical formula be fractions? Explain. Can the coefficients in a balanced chemical equation be fractions? Explain. Changing the subscripts of chemicals can balance the
According to the law of conservation of mass, mass cannot be gained or destroyed in a chemical reaction. Why can’t you simply add the masses of two reactants to determine the total mass of product?
Consider the following generic reaction:In a limiting reactant problem, a certain quantity of each reactant is given and you are usually asked to calculate the mass of product formed. If 10.0 g of Y2
What is the difference between the molar mass and the empirical formula mass of a compound? When are these masses the same, and when are they different? When different, how is the molar mass related
A diamond contains 5.0 × 1021 atoms of carbon. What amount (moles) of carbon and what mass (grams) of carbon are in this diamond?
Calculate the molar mass of the following substances. a. H ON c. (NH4)2Cr2O7 b. Ο Η HZ N
Aluminum metal is produced by passing an electric current through a solution of aluminum oxide (Al2O3) dissolved in molten cryolite (Na3AlF6). Calculate the molar masses of Al2O3 and Na3AlF6.
Calculate the molar mass of the following substances. a. 0 OP b. Ca3(PO4)2 c. Na₂HPO4
Hemoglobin is the protein that transports oxygen in mammals. Hemoglobin is 0.347% Fe by mass, and each hemoglobin molecule contains four iron atoms. Calculate the molar mass of hemoglobin.
Express the composition of each of the following compounds as the mass percents of its elements. a. Formaldehyde, CH2O b. Glucose, C6H12O6 c. Acetic acid, HC2H3O2
Balance the following equations: a. Cr(s) + Sg(s) → Cr₂S3(s) b. NaHCO3(s) Heat, Na₂CO3(s) + CO₂(g) + H₂O(g) c. KCIO3(s) Heat KCl(s) + O₂(g) d. Eu(s) + HF(g) → EuF3(s) + H₂(g)
Considering your answer to Exercise 79, which type of formula, empirical or molecular, can be obtained from elemental analysis that gives percent composition?Data in Exercise 79,Express the
Ammonia is produced from the reaction of nitrogen and hydrogen according to the following balanced equation: a. What is the maximum mass of ammonia that can be produced from a mixture of 1.00 × 103
When the following beakers are mixed, draw a molecular level representation of the product mixture (see Fig. 6.17). + Na+ Br Pb²+ NO3
What is an acid–base reaction? Strong bases are soluble ionic compounds that contain the hydroxide ion. List the strong bases. When a strong base reacts with an acid, what is always produced?
Consider the following electrostatic potential diagrams for some covalent compounds. Which of the represented compounds would not be soluble in water? a. b. C. d. e. f.
Consider the steps involved in balancing oxidation– reduction reactions by using oxidation states. The key to the oxidation states method is to equalize the electrons lost by the species oxidized
Of F2, CF4, and SF2, which substance is most soluble in water? Explain.
A student had 1.00 L of a 1.00-M acid solution. Much to the surprise of the student, it took 2.00 L of 1.00 M NaOH solution to react completely with the acid. Explain why it took twice as much NaOH
Show how each of the following strong electrolytes “breaks up” into its component ions upon dissolving in water by drawing molecular-level pictures.a. NaBr b. MgCl2 c. Al(NO3)3 d.
What mass of solid AgBr is produced when 100.0 mL of 0.150 M AgNO3 is added to 20.0 mL of 1.00 M NaBr?
What volume of 0.0200 M calcium hydroxide is required to neutralize 35.00 mL of 0.0500 M nitric acid?
The concentration of a certain sodium hydroxide solution was determined by using the solution to titrate a sample of potassium hydrogen phthalate (abbreviated as KHP). KHP is an acid with one acidic
Consider the reaction between sodium metal and fluorine (F2) gas to form sodium fluoride. Using oxidation states, how many electrons would each sodium atom lose, and how many electrons would each
Assign the oxidation state for the element listed in each of the following compounds: S in MgSO4 Pb in PbSO4 O in O₂ Ag in Ag Cu in CuCl₂ Oxidation State
Consider the reaction between oxygen (O2) gas and magnesium metal to form magnesium oxide. Using oxidation states, how many electrons would each oxygen atom gain, and how many electrons would each
The blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with an acidic potassium dichromate solution, resulting in the production of Cr3+(aq) and carbon dioxide. The
The vanadium in a sample of ore is converted to VO2+. The VO2+ ion is subsequently titrated with MnO4- in acidic solution to form V(OH)4+ and manganese(II) ion. The unbalanced titration reaction isTo
A 0.500-L sample of H2SO4 solution was analyzed by taking a 100.0-mL aliquot and adding 50.0 mL of 0.213 M NaOH. After the reaction occurred, an excess of OH- ions remained in the solution. The
Without using Fig. 3.4, predict the order of increasing electronegativity in each of the following groups of elements. Data in Fig. 3.4a. Na, K, Rb b. B, O, Ga c. F, Cl, Br d. S, O, F
Describe the type of bonding that exists in the Cl2(g) molecule. How does this type of bonding differ from that found in the HCl(g) molecule? How is it similar?
Without using Fig. 3.4, predict which bond in each of the fol- lowing groups will be the most polar.Data in Fig. 3.4a. C-F, Si-F, Ge-F b. P-Cl or S-Cl c. S-F, S-Cl, S-Br d. Ti-Cl, Si-Cl, Ge-Cl
Without using Fig. 3.4, predict which bond in each of the following groups will be the most polar.Fig. 3.4a. C-H, Si-H, Sn-H b. Al-Br, Ga-Br, In-Br, Tl-Br c. C-O or Si-O d. O-F or O-CI
Which of the following incorrectly shows the bond polarity? Show the correct bond polarity for those that are incorrect.
Predict the empirical formulas of the ionic compounds formed from the following pairs of elements. Name each compound. a. Li and N b. Ga and O c. Rb and Cld. Ba and S
Indicate the bond polarity (show the partial positive and partial negative ends) in the following bonds.a. C-O b. P-H c. H-Cl d. Br-Te e. Se-S
Predict the empirical formulas of the ionic compounds formed from the following pairs of elements. Name each compound. a. Al and Cl b. Na and O c. Sr and F d. Ca and Se
Write Lewis structures that obey the octet rule for each of the following molecules.a. CC14 b. NC13 c. SeCl2d. ICIIn each case, the atom listed first is the central atom.
Write Lewis structures for the following. Show all resonance structures where applicable. a. NO₂, NO3, N₂O4 (N₂O4 exists as O₂N-NO₂.) b. OCN-, SCN-, N₂- (Carbon is the central atom in
Write the formula for each of the following compounds: a. Zinc chloride b. Tin(IV) fluoride c. Calcium nitride d. Aluminum sulfidee. Mercury(I) selenidef. Silver iodide
Write the formula for each of the following compounds:a. Chromium(III) hydroxide b. Magnesium cyanide c. Lead(IV) carbonate d. Ammonium acetate
Write the formula for each of the following compounds: a. Diboron trioxide b. Arsenic pentafluoride c. Dinitrogen monoxide d. Sulfur hexachloride

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