Questions and Answers of General Chemistry

Solid magnesium hydroxide, Mg(OH)2, is added to a solution that is 1.00 M NH4Cl. What is the concentration of Mg2+ in this solution at equilibrium?
Suppose you have a water solution that is 0.0010 M Ca2+ and 0.0010 M Mg2+. Describe the precipitation reactions as you slowly add a concentrated solution of sodium carbonate, Na2CO3, to this
Natural water is said to be “hard” when it contains metal ions such as Ca2+ and Mg2+ that interfere with the use of detergents. These ions are often present in natural water as the soluble
What volume of water would be required to dissolve 10.0 g of silver chloride, AgCl, at 25°C? What volume of 0.15 M NH3 would be required to dissolve the same quantity of silver chloride?
Suppose you add 35.6 mL of 0.578 M Ba(OH)2 to 55.6 mL of 0.491 M H2SO4. What would be the concentrations of Ba2+ and SO42− in the final solution at 25°C? What would be the pH of this solution?
Suppose you add 35.6 mL of 0.578 M H2SO4 to 55.6 mL of 0.491 M Ba(OH)2. What would be the concentrations of Ba2+ and SO42− in the final solution at 25°C? What would be the pH of this solution?
A chemist mixes equal volumes of 0.10 M CaCl2 and 0.15 M NaF in a beaker. What are the concentrations of Ca2+, Na+, Cl−, and F− in the solution in the beaker at 25°C?
Calculate the molar solubility of silver iodide, AgI, in 2.2 M NH3.
How many grams of sodium sulfate can be added to 446 mL of 0.0032 M barium chloride before a precipitate forms?
What must be the concentration of chromate ion in order to precipitate strontium chromate, SrCrO4, from a solution that is 0.0034 M Sr2+?
What is the molar solubility of Al(OH)3 in a solution containing 1.5 × 10−3 M NaOH?
What is the solubility of magnesium hydroxide in a solution buffered at pH 9.20?
What is the molar solubility of ZnS in 0.10 M NH3?
Sufficient sodium cyanide, NaCN, was added to 0.015 M silver nitrate, AgNO3, to give a solution that was initially 0.108 M in cyanide ion, CN−. What is the concentration of silver ion, Ag+, in this
Write the chemical equation for the formation of the Fe(CN)63− ion. Write the Kf expression.
Which salt would you expect to dissolve more readily in acidic solution, strontium phosphate, Sr3(PO4)2, or strontium sulfate, SrSO4? Explain.
Write the net ionic equation in which the slightly soluble salt magnesium carbonate, MgCO3, dissolves in dilute hydrochloric acid.
The following solutions are mixed: 1.0 L of 0.00010 M NaOH and 1.0 L of 0.0014 M MgSO4. Is a precipitate expected? Explain.
The solubility of magnesium fluoride, MgF2, in water is 0.015 g/L. What is the solubility (in grams per liter) of magnesium fluoride in 0.17 M sodium fluoride, NaF?
What is the solubility (in grams per liter) of strontium sulfate, SrSO4, in 0.36 M sodium sulfate, Na2SO4?
What is the solubility of strontium iodate, Sr(IO3)2, in water? The Ksp for Sr(IO3)2 is 1.14 × 10−7.
The pH of a saturated solution of copper(II) hydroxide, Cu(OH)2 was found to be 7.91. From this, find Ksp for copper(II) hydroxide.
The solubility of nickel(II) carbonate, NiCO3, in water is 0.0448 g/L. Calculate Ksp.
The solubility of cobalt(II) iodate in water is 1.2 g/100 mL. Calculate the solubility product constant for cobalt(II) iodate, Co(IO3)2.
Use the solubility rules (Table 4.1) to decide which of the following compounds are expected to be soluble and which insoluble.
You are given a solution of the ions Mg2+, Ca2+, and Ba2+. Devise a scheme to separate these ions using sodium sulfate. Note that magnesium sulfate is soluble.
Weak base B has a pKb of 6.78 and weak acid HA has a pKa of 5.12.a. Which is the stronger base, B or A− ?b. Which is the stronger acid, HA or BH+?c. Consider the following reaction:B(aq) + HA(aq)
A chemist needs a buffer with pH 3.50. How many milliliters of pure formic acid (density = 1.220 g/mL) must be added to 375 mL of 0.0857 M NaOH solution to obtain such a buffer?
The pH of a household cleaning solution is 11.50. This cleanser is an aqueous solution of ammonia with a density of 1.00 g/mL. What is the mass percentage of ammonia in the solution?
A buffer solution is prepared by mixing equal volumes of 0.10 M NaNO2 and 0.10 M HNO2 solutions.a. Calculate the pH of this solution.b. How would the buffer capacity of 500 mL of this buffer solution
A solution of weak base is titrated to the equivalence point with a strong acid. Which one of the following statements is most likely to be correct?a. The pH of the solution at the equivalence point
A sample of NH4Cl is prepared for titration by dissolving the salt in water, making 100.0 mL of solution. A second sample of NH4Cl of identical mass is used to prepare 200.0 mL of solution. A
A solution is prepared by dissolving ammonium nitrite in water. Predict whether the solution would be acidic or basic. If you want to make the solution have a neutral pH, which of the following could
The Kb for NH3 is 1.8 × 10−5 at 25°C. Calculate the pH of a buffer solution made by mixing 65.1 mL of 0.142 M NH3 with 38.0 mL of 0.172 M NH4Cl at 25°C. Assume that the volumes of the solutions
Calculate the pH of a solution made by mixing 0.62 L of 0.10 M NH4Cl with 0.50 L of 0.10 M NaOH. Kb for NH3 is 1.8 × 10−5.
A 0.108 M sample of a weak acid is 3.95% ionized in solution. What is the hydroxide concentration of this solution?
What is the pH of the solution obtained by titrating 1.30 g of sodium hydrogen sulfate, NaHSO4, dissolved in 50.0 mL of water with 0.175 M sodium hydroxide until the equivalence point is reached?
Codeine, C18H21NO3, is an alkaloid (Kb = 6.2 × 10−9) used as a painkiller and cough suppressant. A solution of codeine is acidified with hydrochloric acid to pH 4.50. What is the ratio of the
A buffer is made by dissolving 12.5 g of sodium dihydrogen phosphate, NaH2PO4, and 15.0 g of disodium hydrogen phosphate, Na2HPO4, in a liter of solution. What is the pH of the buffer?
Calculate the pH of a 0.072 M aqueous solution of aluminum chloride, AlCl3. The acid ionization of hydrated aluminum ion isAl(H2O)63+(aq) + H2O(l) ⇌ Al(H2O)5OH2+(aq) + H3O+(aq)and Ka is 1.4 × 10-5.
Calculate the pH of a solution obtained by mixing 35.0 mL of 0.15 M acetic acid with 27.0 mL of 0.10 M sodium acetate.
Calculate the pH of a solution obtained by mixing 25.00 mL of 0.19 M NH3 with 25.00 mL of 0.060 M HCl.
What is the pH at the equivalence point when 22 mL of 0.20 M hydroxylamine is titrated with 0.10 M HCl?
What is the pH of a solution in which 35 mL of 0.10 M NaOH is added to 25 mL of 0.10 M HCl?
How many moles of hydrofluoric acid, HF, must be added to 250 mL of 0.25 M sodium fluoride to give a buffer of pH 3.50? Ignore the volume change due to the addition of hydrofluoric acid.
How many moles of sodium acetate must be added to 2.0 L of 0.10 M acetic acid to give a solution that has a pH equal to 4.90? Ignore the volume change due to the addition of sodium acetate.
A buffer is prepared by adding 115 mL of 0.30 M NH3 to 135 mL of 0.15 M NH4NO3. What is the pH of the final solution?
A buffer is prepared by adding 39.8 mL of 0.75 M NaF to 38.9 mL of 0.28 M HF. What is the pH of the final solution?
What is the pH of a solution that is 0.600 M HCHO2 (formic acid) and 0.400 M NaCHO2?
What is the pH of a 0.30 M solution of methylammonium chloride, CH3NH3Cl? What is the concentration of methylamine in the solution?
Calculate the OH− concentration and pH of a 0.0025 M aqueous solution of sodium cyanide, NaCN. Finally, obtain the hydronium-ion, CN−, and HCN concentrations.
Obtain a. The Kb value for C3H3O2−; b. The Ka value for NH3OH+ (hydroxylammonium ion).
Note whether the aqueous solution of each of the following salts will be acidic, basic, or neutral.a. Na2S b. Cu(NO2)2c. KNO3 d. CH3NH3Cl
For each of the following salts, indicate whether the aqueous solution will be acidic, basic, or neutral.a. Zn(NO3)2 b. K2SO4c. NH2NH3ClO4 d. K2SO3
Note whether hydrolysis occurs for each of the following ions. If hydrolysis does occur, write the chemical equation for it. Then write the equilibrium expression for the acid or base ionization
What is the concentration of hydroxide ion in a 0.21 M aqueous solution of hydroxylamine, NH2OH? What is the pH?
Butylamine, C4H9NH2 is a weak base. A 0.47 M aqueous solution of butylamine has a pH of 12.13. What is Kb for butylamine? Calculate the pH of a 0.35 M aqueous solution of butylamine.
What is the hydronium-ion concentration of a 3.00 × 10–4 M solution of p-bromobenzoic acid, BrC6H4COOH, for which Ka = 1.00 × 10–4?
A chemist wanted to determine the concentration of a solution of lactic acid, HC3H5O3. She found that the pH of the solution was 2.60. What was the concentration of the solution? The Ka of lactic
A solution of acetic acid, HC2H3O2, on a laboratory shelf was of undetermined concentration. If the pH of the solution was found to be 2.57, what was the concentration of the acetic acid? The Ka of
C6H4NH2COOH, para-aminobenzoic acid (PABA), is used in some sunscreen agents. Calculate the concentrations of hydronium ion and para-aminobenzoate ion, C6H4NH2COO-, in a 0.080 M solution of the acid.
Formic acid, HCHO2, is used to make methyl formate (a fumigant for dried fruit) and ethyl formate (an artificial rum flavor). What is the pH of a 0.12 M solution of formic acid? What is the degree of
Boric acid, B(OH)3, is used as a mild antiseptic. What is the pH of a 0.015 M aqueous solution of boric acid? What is the degree of ionization of boric acid in this solution? The hydronium ion arises
Acrylic acid, whose formula is HC3H3O2 or HO2CCH═CH2, is used in the manufacture of plastics. A 0.77 M aqueous solution of acrylic acid has a pH of 2.18. What is K a for acrylic acid?
H2A is a weak diprotic acid having Ka1 = 4.5 × 10−4 and Ka2 = 6.7 × 10−8. If the concentration of H2A is 0.45 M, what is the concentration of A2−?
The chemical equation for the hydrolysis of nitrous acid isHNO2(aq) + H2O(l) ⇌ H3O+ (aq) + NO2−(aq)Which of the following, when added to a nitrous acid solution, would reduce the degree of
You place 4.00 mol of dinitrogen trioxide, N2O3, into a flask, where it decomposes at 25.0°C and 1.00 atm:N2O3(g) ⇌ NO2(g) + NO(g)What is the composition of the reaction mixture at equilibrium if
Consider all A—B bonds that can be formed between any two of the four elements germanium (Ge) to bromine (Br) in Period 4. Which bond should be the most polar? What is the covalent single bond
A stock solution of potassium dichromate, K2Cr2O7, is made by dissolving 84.5 g of the compound in 1.00 L of solution. How many milliliters of this solution are required to prepare 1.00 L of 0.150 M
Potassium hydrogen phthalate (abbreviated as KHP) has the molecular formula KHC8H4O4 and a molar mass of 204.22 g/mol. KHP has one acidic hydrogen. A solid sample of KHP is dissolved in 50 mL of
An alloy of aluminum and magnesium was treated with sodium hydroxide solution, in which only aluminum reacts.If a sample of alloy weighing 1.225 g gave 0.1093 g of hydrogen, what is the percentage of
An alloy of iron and carbon was treated with sulfuric acid, in which only iron reacts.2Fe(s) + 3H2SO4(aq) → Fe2(SO4)3(aq) + 3H2(g)If a sample of alloy weighing 2.358 g gave 0.1067 g of hydrogen,
When using H2SO4 in aqueous reactions, many problems are presented or solved by assuming both of the hydrogen ions to be strongly ionized, as if they were both strong acid ionization processes. At
An experiment calls for 3.70 mol of chlorine, Cl2. What volume will this be if the gas volume is measured at 36°C and 3.30 atm?
Why is it important to give the states of the reactants and products when giving an equation for ∆H?
If an equation for a reaction is doubled and then reversed, how is the value of ∆H changed?
A 5.0-g sample of water starting at 60.0°C loses 418 J of energy in the form of heat. What is the final temperature of the water after this heat loss?a. 20.°C b. 40.°Cc. 50.°C d.
Chemical reactions are run in each of the beakers depicted below (labeled A, B, and C). The magnitude and direction of heat and work for each reaction are represented as arrows, with the length of an
The process of dissolving ammonium nitrate, NH4NO3, in water is an endothermic process. What is the sign of q? If you were to add some ammonium nitrate to water in a flask, would you expect the flask
Give the electron configuration of the ground state of nickel, using the building-up principle.
For eka-bismuth, predict the electron configuration, whether the element is a metal or nonmetal, and the formula of an oxide.
A neutral atom has the electron configuration 1s22s22p63s13p2. Is this the ground-state configuration? What is the period and column of the element? What is the name of the element? What is the
Write the electron configurations of Pb and Pb2+.
Why does sodium chloride normally exist as a crystal rather than as a molecule composed of one cation and one anion?
Without looking at Table 9.3, arrange the following ions in order of increasing ionic radius: Sr2+, Mg2+, Ca2+. (You may use a periodic table.) Table 9.3 lonic Radii (in pm) of Some Main-Group
Using electronegativities, decide which of the following bonds is most polar: C—O, C—S, H—Br.
What is the qualitative relationship between bond polarity and electronegativity difference?
Estimate the O—H bond length in H2O from the covalent radii listed in Table 9.4. Table 9.4 Single-Bond Covalent Radi Atomic Covalent Atomic Covalent Number Symbol Name Radius (pm) Number Symbol
Formic acid, isolated in 1670, is the irritant in ant bites. The structure of formic acid isOne of the carbon–oxygen bonds has a length of 136 pm; the other is 123 pm long. What is the length of
Which of the following contains both ionic and covalent bonds in the same compound?a. CO32− b. BaSO3c. SrO d. HIe. MgS
The radii of the species S, S+, and S− decrease in the following order:a. S+ > S > S− b. S+ > S > S−c. S > S− > S+ d. S > S+ > S−e. S− > S > S+
Which of the following is the ground-state electron configuration of a C3- ion?a. 1s22s22p4 b. [He]2s22p6c. [He]2s1 d. 1s22s22p5e. 1s22s22p63s1
The element X below could bea. Sulfurb. Iodinec. Aluminumd. Phosphoruse. Silicon X.
Which of the following represent configurations of indium ions in compounds? Explain your decision in each case.a. In4+ [Kr]4d9 b. In+ [Kr]4d105s2c. In3+ [Kr]4d10 d. In [Kr]4d105s1
Lithium, Li, reacts with element X to form an ionic compound with the formula Li2X.a. What is the formula of the compound you expect to form when aluminum, Al, reacts with element X?b. Would you
Write Lewis symbols for the following:a. Br b. Br− c. Ga d. Ga3+
Write Lewis symbols for the following:a. O b. O2− c. Ca d. Ca2+
For each of the following, use formal charges to choose the Lewis formula that gives the best description of the electron distribution:a. ClO2Fb. SO2c. ClO3-
Use Lewis symbols to represent the electron transfer between the following atoms to give ions with noble-gas configurations:a. Ba and I b. Sr and O
For each of the following, write the electron configuration and Lewis symbol:a. Ge b. Ge2+ c. K+ d. I−

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