Questions and Answers of General Chemistry

How much heat must be added to 50.0 g of solid sodium, Na, at 25.0°C to give the liquid at its melting point, 97.8°C? The heat capacity of solid sodium is 28.2 J/(K ∙ mol), and its heat of
Which of the following compounds is likely to be more soluble in water: C4H9OH or C4H9SH? Explain.
You have two molecular compounds, X and Y. Compound X has stronger intermolecular forces than compound Y. X has no dipole–dipole bonding of any kind, and Y exhibits hydrogen bonding. Predict the
Which ion has the larger hydration energy, Na+ or K+?
Colloidal sulfur particles are negatively charged with thiosulfate ions, S2O32−, and other ions on the surface of the sulfur. Indicate which of the following would be most effective in coagulating
How would you prepare 78.0 g of an aqueous solution that is 5.00% potassium iodide, KI, by mass?
How would you prepare 455 g of an aqueous solution that is 7.00% sodium sulfate, Na2SO4, by mass?
Lauryl alcohol, C12H25OH, is prepared from coconut oil; it is used to make sodium lauryl sulfate, a synthetic detergent. What is the molality of lauryl alcohol in a solution of 17.1 g lauryl alcohol
An automobile antifreeze solution contains 2.50 kg of ethylene glycol, CH2OHCH2OH, and 2.25 kg of water. Find the mole fraction of ethylene glycol in this solution. What is the mole fraction of water?
An antiseptic solution contains hydrogen peroxide, H2O2, in water. The solution is 0.610 m H2O2. What is the mole fraction of hydrogen peroxide?
Concentrated aqueous ammonia contains 1.00 mol NH3 dissolved in 2.50 mol H2O. What is the mole fraction of NH3 in concentrated aqueous ammonia? What is the molal concentration of NH3?
Calculate the vapor pressure at 35°C of a solution made by dissolving 24.8 g of sucrose, C12H22O11, in 70.1 g of water. The vapor pressure of pure water at 35°C is 42.2 mmHg. What is the
What is the boiling point of a solution of 0.133 g of glycerol, C3H8O3, in 20.0 g of water? What is the freezing point?
A solution was prepared by dissolving 0.800 g of sulfur, S8, in 100.0 g of acetic acid, HC2H3O2. Calculate the freezing point and boiling point of the solution.
Urea, (NH2)2CO, is dissolved in 250.0 g of water. The solution freezes at -0.085°C. How many grams of urea were dissolved to make this solution?
Dextran is a polymeric carbohydrate produced by certain bacteria. It is used as a blood plasma substitute. An aqueous solution contains 0.587 g of dextran in 106 mL of solution at 21°C. It has an
What is the freezing point of 0.0088 m aqueous sodium phosphate, Na3PO4? Use the formula of the salt to obtain i.
A gaseous mixture consists of 87.0 mole percent N2 and 13.0 mole percent O2 (the approximate composition of air). Suppose water is saturated with the gas mixture at 25°C and 1.00 atm total pressure,
A natural gas mixture consists of 88.0 mole percent CH4 (methane) and 12.0 mole percent C2H6 (ethane). Suppose water is saturated with the gas mixture at 20°C and 1.00 atm total pressure, and the
An aqueous solution is 14.0% ammonium chloride, NH4Cl, by mass. The density of the solution is 1.040 g/mL. What are the molality, mole fraction, and molarity of NH4Cl in the solution?
A 55-g sample of a gaseous fuel mixture contains 0.43 mole fraction propane, C3H8; the remainder of the mixture is butane, C4H10. What are the masses of propane and butane in the sample?
A liquid solution consists of 0.30 mole fraction ethylene dibromide, C2H4Br2, and 0.70 mole fraction propylene dibromide, C3H6Br2. Both ethylene dibromide and propylene dibromide are volatile
Maltose, C12H22O11, is a sugar produced by malting (sprouting) grain. A solution of maltose at 25°C has an osmotic pressure of 5.00 atm. What is the molar concentration of maltose?
Which aqueous solution has the lower freezing point, 0.60 m CaCl2 or 0.60 m glucose?
Which aqueous solution has the lower boiling point, 0.10 m NaBr or 0.10 m CaCl2?
The carbohydrate digitoxose contains 48.64% carbon and 8.16% hydrogen. The addition of 18.0 g of this Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated,
Fish blood has an osmotic pressure equal to that of seawater. If seawater freezes at −2.3°C, what is the osmotic pressure of the blood at 20°C? To solve this problem, what assumptions must be
A salt solution has an osmotic pressure of 16 atmospheres at 22°C. What is the freezing point of this solution? What assumptions must be made to solve this problem?
A sample of an ionic solid is dissolved in 1.00 kg of water. The freezing point of the water is −0.01°C. If three times the mass of ionic solid is dissolved in 1.00 kg of water and the resulting
Which of the following ways of expressing concentration would be most likely to change with a change in temperature: molarity, molality, or mass percentage? Explain your reasoning.
Methanol, CH3OH, is a compound that is used in car windshield washer fluid to lower the freezing point of the solution. If an aqueous solution of windshield washer fluid has a mole fraction of
Although somewhat toxic, barium chloride has been used as a cardiac stimulant. Calculate the number of moles of barium chloride in 427 g of a 3.25% by mass barium chloride solution?
A solution is made up by dissolving 15.0 g MgSO4∙7H2O in 140.0 g of water. What is the molality of MgSO4 in this solution?
A solution is made up by dissolving 18.0 g Na2CO3∙10H2O in 100.0 g of water. What is the molality of Na2CO3 in this solution?
The reaction A(g) h B(g) + C(g) is known to be first order in A(g). It takes 28 s for the concentration of A(g) to decrease by one-half of its initial value. How long does it take for the
Relate the rate of decomposition of NH4NO2 to the rate of formation of N2 for the following reaction:NH4NO2(aq) → N2(g) + 2H2O(l )
A reaction of the form aA → Products is secondorder with a rate constant of 0.725 L/(mol ∙ s). If the initial concentration of A is 0.760 mol/L, what is the molar concentration of A after
A reaction of the form aA → Products is second order with a rate constant of 0.169 L/(mol ∙ s). If the initial concentration of A is 0.159 mol/L, how many seconds would it take for the
A reaction of the form aA → Products is second order with a rate constant of 0.164 L/(mol ∙ s). What is the half-life, in seconds, of the reaction if the initial concentration of A is 5.55 ×
A reaction of the form aA → Products is second order with a half-life of 485 s. What is the rate constant of the reaction if the initial concentration of A is 5.99 × 10-3 mol/L?
The reaction A → B + C is found to be zero order. If it takes 5.2 × 102 seconds for an initial concentration of A to go from 0.50 M to 0.25 M, what is the rate constant for the reaction?
Write a rate equation, showing the dependence of rate on reactant concentrations, for each of the following elementary reactions.a. CS2 → CS + Sb. CH3Br + OH− → CH3OH + Br−
A compound decomposes by a first-order reaction. If the concentration of the compound is 0.0569 M after 40. s when the initial concentration was 0.0700 M, what is the concentration of the compound
The rate constant for a certain reaction is 1.4 × 10−5 M−1 min−1 at 483 K. The activation energy for the reaction is 2.11 × 103 J/mol. What is the rate constant for the reaction at 611 K?
A reaction of the form aA → Products is second order with a half-life of 287 s. What is the rate constant of the reaction if the initial concentration of A is 1.87 × 10-2 mol/L?
For many reactions, the reaction rate approximately doubles with every 10°C increase in temperature. Using this approximation, if a reaction were run at 35°C and then at 75°C, how would the
Consider the possibility of converting carbon dioxide to carbon monoxide by the endothermic reactionCO2(g) + H2(g) ⇌ CO(g) + H2O(g)Is a high or a low temperature more favorable to the production of
A 2.50-L vessel contains 1.75 mol N2, 1.75 mol H2, and 0.346 mol NH3. What is the direction of reaction (forward or reverse) needed to attain equilibrium at 401°C? The equilibrium constant Kc for
A vessel originally contained 0.0200 mol iodine monobromide (IBr), 0.050 mol I2, and 0.050 mol Br2. The equilibrium constant Kc for the reactionI2(g) + Br2(g) ⇌ 2IBr(g)is 1.2 × 102 at 150°C. What
A container with a volume of 1.500 L was evacuated and then filled at low temperature with 0.0500 mol liquid dinitrogen tetroxide, N2O4. As the temperature was raised, this substance formed nitrogen
Determine the direction of the following reaction from the relative strengths of acids and bases.H2S(aq) + C2H3O2-(aq) ⇌ HC2H3O2(aq) + HS2(aq)
The pH of a solution is 9.55 at 25°C. What is the hydroxide-ion concentration in the solution?a. 2.8 × 10−10 M b. 3.5 × 10−5 Mc. 3.1 × 10−10 M d. 3.2 × 10−5 Me. 3.8 × 10−5 M
Write the balanced reaction of hypobromous acid, HOBr, with water to form hydronium ion and the conjugate base of HOBr. Identify each species as either an acid or a base.
Give the conjugate base to each of the following species regarded as acids:a. HSO4− b. PH4+c. HSe− d. HOBr
Give the conjugate acid to each of the following species regarded as bases.a. HS− b. NH2−c. BrO2− d. N2H4
A solution of hydrochloric acid is 0.059 M HCl. What is the hydronium-ion concentration at 25°C? What is the hydroxide-ion concentration at 25°C?
A detergent solution has a pH of 11.80 at 25°C. What is the hydroxide-ion concentration?
A solution is 0.030 M HNO3 (nitric acid). What is the hydronium-ion concentration at 25°C? What is the hydroxide-ion concentration at 25°C?
The following are solution concentrations. Indicate whether each solution is acidic, basic, or neutral.a. 2 × 10−11 M OH− b. 2 × 10−6 M H3O+c. 6 × 10−10 M OH− d. 6 × 10−3 M
Which of the following pH values indicate an acidic solution at 25°C? Which are basic and which are neutral?a. 12.9 b. 8.9 c. 5.1 d. 1.6
Obtain the pH corresponding to the following hydronium-ion concentrations.a. 1.0 × 10−4 M b. 3.2 × 10−10 Mc. 2.3 × 10−5 M d. 2.91 × 10−11 M
A sample of vinegar has a hydronium-ion concentration of 3.0 × 10−3 M. What is the pH of the vinegar?
Obtain the pH corresponding to the following hydroxide-ion concentrations.a. 4.35 × 10−9 M b. 7.3 × 10−3 Mc. 2.6 × 10−12 M d. 1.1 × 10−8 M
Obtain the pH corresponding to the following hydroxide-ion concentrations.a. 4.83 × 10−11 M b. 3.2 × 10−5 Mc. 2.7 × 10−10 M d. 5.0 × 10−4 M
Which of the following substances are acids in terms of the Arrhenius concept? Which are bases? Show the acid or base character by using chemical equations.a. P4O10 b. Na2O c. N2H4 d.
A solution is 0.18 M KOH. What are the concentrations of H3O+ and OH− in this solution?
A solution is 0.25 M Sr(OH)2. What are the concentrations of H3O+ and OH- in this solution?
A sample of lemon juice has a hydronium-ion concentration equal to 2.6 × 10−2 M. What is the pH of this sample?
A sample of apple cider has a pH of 3.75. What is the hydroxide-ion concentration of this solution?
A sample of grape juice has a pH of 4.15. What is the hydroxide-ion concentration of this solution?
A 4.640-g sample of a mixture of sodium hydrogen carbonate and potassium chloride is dissolved in 25.20 mL of 0.444 M H2SO4. Some acid remains after treatment of the sample.a. Write both the net
a. Consider the hydrated aluminum ion Al(H2O)63+ as a Brønsted–Lowry acid. Write the chemical equation in which this ion loses a proton in a reaction with ammonia, NH3. Identify the conjugate
Saccharin, HC7H4NO3S, is a well-known sweetener. It is a weak acid, and as the sweetener, it is generally supplied as the sodium salt. Here is the structural formula for the saccharin molecule. From
Consider the acids listed and decide on the basis of their structures how you would order them, from weakest to strongest. Explain your reasoning. capright 20r Cengaga Leaning Al 2-chloropropanoic
Hydrazine, N2H4 (having the structure H2NNH2), and its derivatives have been used as rocket fuels. Draw the Lewis electron-dot formula for the hydrazine molecule.Describe the geometries expected
Consider the substances arsine, AsH3, and phosphine, PH3, that are analogous to ammonia, NH3. Write chemical equations illustrating the basic character of arsine and phosphine. Write formulas for the
Suppose you have 557 mL of 0.0300 M HCl, and you want to make up a solution of HCl that has a pH of 1.751. What is the maximum volume (in liters) that you can make of this solution?
What is meant by the thermodynamic standard state?
The equation for the combustion of 2 mol of butane can be written2C4H10(g) + O2(g) → 8CO2(g) + 10H2O(g); ∆H < OWhich of the following produces the least heat?a. Burning 1 mol of butane.b.
A bullet weighing 235 grains is moving at a speed of 2.52 × 103 ft/s. Calculate the kinetic energy of the bullet in joules and in calories. One grain equals 0.0648 g
An iron skillet weighing 1.63 kg is heated on a stove to 178°C. Suppose the skillet is cooled to room temperature, 21°C. How much heat energy (in joules) must be removed to affect this cooling? The
When ice at 0°C melts to liquid water at 0°C, it absorbs 0.334 kJ of heat per gram. Suppose the heat needed to melt 38.0 g of ice is absorbed from the water contained in a glass. If this water has
Give the equation that relates particle properties of light. Explain the meaning of each symbol in the equation.
What is the evidence for electron waves? Give a practical application.
What is the wavelength of the electromagnetic radiation emitted from a hydrogen atom when the electron undergoes the transition n = 4 to n = 1? In what region of the spectrum does this line occur?
What is the difference in energy between the two levels responsible for a red emission line of the strontium atom at 640.8 nm?
What is the wavelength of a neutron traveling at a speed of 4.54 km/s?
What is the wavelength of a proton traveling at a speed of 6.21 km/s? What would be the region of the spectrum for electromagnetic radiation of this wavelength?
What is the de Broglie wavelength of a 149-g baseball traveling at 23.0 m/s (51.4 mph)? Is the wavelength much smaller or much larger than the diameter of an atom (on the order of 100 pm)?
The surface of a metal was illuminated with light whose wavelength is 327 nm. Upon illumination, the metal ejected an electron with a speed of 3.46 × 105 m/s. What is the photoelectric work function
A hydrogen atom in the ground state absorbs a photon whose wavelength is 95.0 nm. The resulting excited atom then emits a photon of 1282 nm. What are the regions of the electromagnetic spectrum for
What is the name of the alkali metal atom with valence shell configuration 6s1?
When trying to remove electrons from Be, which of the following sets of ionization energy makes the most sense going from first to third ionization energy? Explain your answer.a. First IE 900 KJ/mol,
An atom of an element has the following ground-state configuration: [Xe]4f145d96s1. Using this configuration, give the symbol of the element. Explain your reasoning.
How does the enthalpy change for an endothermic reaction occurring at constant pressure?
Under what condition is the enthalpy change equal to the heat of reaction?
Suppose heat flows into a vessel containing a gas. As the heat flows into the gas, what happens to the gas molecules? What happens to the internal energy of the gas?
What is the original definition of the calorie? What is the present definition?
Define the joule in terms of SI base units.
A sample of a breathing mixture for divers contained 34.3% helium, He; 51.7% nitrogen, N2; and 14.0% oxygen, O2 (by mass). What is the density of this mixture at 22°C and 775 mmHg?

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