Exercises

Why does the reactivity of the alkali metals decrease from cesium to lithium?

Predict the best choice in each of the following. You may wish to review the chapter on electronic structure for relevant examples.

(a) the most metallic of the elements Al, Be, and Ba

(b) the most covalent of the compounds NaCl, CaCl₂, and BeCl₂

(c) the lowest first ionization energy among the elements Rb, K, and Li

(d) the smallest among Al, Al⁺, and Al³⁺

(e) the largest among Cs⁺, Ba²⁺, and Xe

The reaction of quicklime, CaO, with water produces slaked lime, Ca(OH)₂, which is widely used in the construction industry to make mortar and plaster. The reaction of quicklime and water is highly exothermic:
$\text{CaO}(s)+{\text{H}}_2\text{O}(l)⟶\text{Ca}{(\text{OH})}_2(s)\text{Δ}H=\text{−350 kJ}{\text{mol}}^{\text{−1}}$

(a) What is the enthalpy of reaction per gram of quicklime that reacts?

(b) How much heat, in kilojoules, is associated with the production of 1 ton of slaked lime?

How many moles of ionic species are present in 1.0 L of a solution marked 1.0 M mercury(I) nitrate?

The elements sodium, aluminum, and chlorine are in the same period.

(a) Which has the greatest electronegativity?

(b) Which of the atoms is smallest?

(c) Write the Lewis structure for the simplest covalent compound that can form between aluminum and chlorine.

(d) Will the oxide of each element be acidic, basic, or amphoteric?

What is tin pest, also known as tin disease?

Is the reaction of rubidium with water more or less vigorous than that of sodium? How does the rate of reaction of magnesium compare?

Why is it necessary to keep the chlorine and sodium, resulting from the electrolysis of sodium chloride, separate during the production of sodium metal?

The electrolysis of molten sodium chloride or of aqueous sodium chloride produces chlorine.

Calculate the mass of chlorine produced from 3.00 kg sodium chloride in each case. You may wish to review the chapter on electrochemistry for relevant examples.

How many grams of oxygen gas are necessary to react completely with 3.01 $\times$ 10²¹ atoms of magnesium to yield magnesium oxide?

Why is it possible for an active metal like aluminum to be useful as a structural metal?

What is the common ore of tin and how is tin separated from it?

Consider the production of 100 kg of sodium metal using a current of 50,000 A, assuming a 100% yield.

(a) How long will it take to produce the 100 kg of sodium metal?

(b) What volume of chlorine at 25 °C and 1.00 atm forms?

Give the hybridization of the metalloid and the molecular geometry for each of the following compounds or ions. You may wish to review the chapters on chemical bonding and advanced covalent bonding for relevant examples.

(a) GeH₄

(b) SbF₃

(c) Te(OH)₆

(d) H₂Te

(e) GeF₂

(f) TeCl₄

(g) ${\text{SiF}}_6{}^{\mathrm{2-}}$

(h) SbCl₅

(i) TeF₆

Describe the hybridization of boron and the molecular structure about the boron in each of the following:

(a) H₃BPH₃

(b) ${\text{BF}}_4{}^{-}$

(c) BBr₃

(d) B(CH₃)₃

(e) B(OH)₃

Write a Lewis structure for each of the following molecules and ions:

(a) (CH₃)₃SiH

(b) ${\text{SiO}}_4{}^{\mathrm{4-}}$

(c) Si₂H₆

(d) Si(OH)₄

(e) ${\text{SiF}}_6{}^{\mathrm{2-}}$

Describe the hybridization and the bonding of a silicon atom in elemental silicon.

Silicon reacts with sulfur at elevated temperatures. If 0.0923 g of silicon reacts with sulfur to give 0.3030 g of silicon sulfide, determine the empirical formula of silicon sulfide.

Write a balanced equation for the reaction of elemental boron with each of the following (most of these reactions require high temperature):

(a) F₂

(b) O₂

(c) S

(d) Se

(e) Br₂

Write a formula for each of the following compounds:

(a) silicon dioxide

(b) silicon tetraiodide

(c) silane

(d) silicon carbide

(e) magnesium silicide

A hydride of silicon prepared by the reaction of Mg₂Si with acid exerted a pressure of 306 torr at 26 °C in a bulb with a volume of 57.0 mL. If the mass of the hydride was 0.0861 g, what is its molecular mass? What is the molecular formula for the hydride?

Carbon forms a number of allotropes, two of which are graphite and diamond. Silicon has a diamond structure. Why is there no allotrope of silicon with a graphite structure?

Write balanced chemical equations for the reaction of the following acid anhydrides with water:

(a) SO₃

(b) N₂O₃

(c) Cl₂O₇

(d) P₄O₁₀

(e) NO₂

Determine the oxidation state of sulfur in each of the following:

(a) SO₃

(b) SO₂

(c) ${\text{SO}}_3{}^{\mathrm{2-}}$

Why does white phosphorus consist of tetrahedral P₄ molecules while nitrogen consists of diatomic N₂ molecules?

The reaction of calcium hydride, CaH₂, with water can be characterized as a Lewis acid-base reaction:
${\text{CaH}}_2(s)+{\text{2H}}_2\text{O}(l)⟶\text{Ca}{(\text{OH})}_2(aq)+{\text{2H}}_2(g)$

Identify the Lewis acid and the Lewis base among the reactants. The reaction is also an oxidation-reduction reaction. Identify the oxidizing agent, the reducing agent, and the changes in oxidation number that occur in the reaction.

What mass of CaH₂ is necessary to react with water to provide enough hydrogen gas to fill a balloon at 20 °C and 0.8 atm pressure with a volume of 4.5 L? The balanced equation is:
${\text{CaH}}_2(s)+{\text{2H}}_2\text{O}(l)⟶\text{Ca}{(\text{OH})}_2(aq)+{\text{2H}}_2(g)$

Carbon forms the ${\text{CO}}_3{}^{\mathrm{2-}}$ ion, yet silicon does not form an analogous ${\text{SiO}}_3{}^{\mathrm{2-}}$ ion. Why?

Heating a sample of Na₂CO₃⋅xH₂O weighing 4.640 g until the removal of the water of hydration leaves 1.720 g of anhydrous Na₂CO₃. What is the formula of the hydrated compound?

For each of the following, indicate the hybridization of the nitrogen atom (for ${\text{N}}_3{}^{\text{−}},$ the central nitrogen).

(a) N₂F₄

(b) ${\text{NH}}_2{}^{-}$

(c) NF₃

(d) ${\text{N}}_3{}^{-}$

Determine the oxidation state of nitrogen in each of the following. You may wish to review the chapter on chemical bonding for relevant examples.

(a) NCl₃

(b) ClNO

(c) N₂O₅

(d) N₂O₃

(e) ${\text{NO}}_2{}^{-}$

(f) N₂O₄

(g) N₂O

(h) ${\text{NO}}_3{}^{-}$

(i) HNO₂

(j) HNO₃

How many grams of gaseous ammonia will the reaction of 3.0 g hydrogen gas and 3.0 g of nitrogen gas produce?

The equivalence point for the titration of a 25.00-mL sample of CsOH solution with 0.1062 M HNO₃ is at 35.27 mL. What is the concentration of the CsOH solution?

Describe the molecular structure of each of the following molecules or ions listed. You may wish to review the chapter on chemical bonding and molecular geometry.

(a) PH₃

(b) ${\text{PH}}_4{}^{+}$

(c) P₂H₄

(d) ${\text{PO}}_4{}^{\mathrm{3-}}$

Describe the hybridization of phosphorus in each of the following compounds: P₄O₁₀, P₄O₆, PH₄I (an ionic compound), PBr₃, H₃PO₄, H₃PO₃, PH₃, and P₂H₄. You may wish to review the chapter on advanced theories of covalent bonding.

How much POCl₃ can form from 25.0 g of PCl₅ and the appropriate amount of H₂O?

Write equations showing the stepwise ionization of phosphorous acid.

Why does phosphorous acid form only two series of salts, even though the molecule contains three hydrogen atoms?

Phosphoric acid, one of the acids used in some cola drinks, is produced by the reaction of phosphorus(V) oxide, an acidic oxide, with water. Phosphorus(V) oxide is prepared by the combustion of phosphorus.

(a) Write the empirical formula of phosphorus(V) oxide.

(b) What is the molecular formula of phosphorus(V) oxide if the molar mass is about 280.

(c) Write balanced equations for the production of phosphorus(V) oxide and phosphoric acid.

(d) Determine the mass of phosphorus required to make 1.00 $\times$ 10⁴ kg of phosphoric acid, assuming a yield of 98.85%.

Using equations, describe the reaction of water with potassium and with potassium oxide.

Write balanced chemical equations for the following reactions:

(a) cadmium burned in air

(b) elemental cadmium added to a solution of hydrochloric acid

(c) cadmium hydroxide added to a solution of acetic acid, CH₃CO₂H

Write balanced chemical equations for the following reactions:

(a) metallic aluminum burned in air

(b) elemental aluminum heated in an atmosphere of chlorine

(c) aluminum heated in hydrogen bromide gas

(d) aluminum hydroxide added to a solution of nitric acid

What volume of 0.250 M H₂SO₄ solution is required to neutralize a solution that contains 5.00 g of CaCO₃?

Write a balanced chemical equation for the reaction of an excess of oxygen with each of the following. Remember that oxygen is a strong oxidizing agent and tends to oxidize an element to its maximum oxidation state.

(a) Mg

(b) Rb

(c) Ga

(d) C₂H₂

(e) CO

Explain why hydrogen sulfide is a gas at room temperature, whereas water, which has a lower molecular mass, is a liquid.

Which is the stronger acid, NaHSO₃ or NaHSO₄?

Which is a stronger acid, sulfurous acid or sulfuric acid? Why?

Give the Lewis structure of each of the following:

(a) SF₄

(b) K₂SO₄

(c) SO₂Cl₂

(d) H₂SO₃

(e) SO₃

Explain why sulfuric acid, H₂SO₄, which is a covalent molecule, dissolves in water and produces a solution that contains ions.

What does it mean to say that mercury(II) halides are weak electrolytes?

The following reactions are all similar to those of the industrial chemicals. Complete and balance the equations for these reactions:

(a) reaction of a weak base and a strong acid
${\text{NH}}_3+{\text{HClO}}_4⟶$

(b) preparation of a soluble silver salt for silver plating
${\text{Ag}}_2{\text{CO}}_3+{\text{HNO}}_3⟶$

(c) preparation of strontium hydroxide by electrolysis of a solution of strontium chloride
${\text{SrCl}}_2(aq)+{\text{H}}_2\text{O}(l)\stackrel{\text{electrolysis}}{\to }$

What is the hybridization of iodine in IF₃ and IF₅?

Which halogen has the highest ionization energy? Is this what you would predict based on what you have learned about periodic properties?

Explain why, at room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid.

Physiological saline concentration—that is, the sodium chloride concentration in our bodies—is approximately 0.16 M. A saline solution for contact lenses is prepared to match the physiological concentration. If you purchase 25 mL of contact lens saline solution, how many grams of sodium chloride have you bought?

What is the molecular structure of each of the following molecules? You may wish to review the chapter on chemical bonding and molecular geometry.

(a) XeF₂

(b) XeF₄

(c) XeO₃

(d) XeO₄

(e) XeOF₄

What is the oxidation state of the noble gas in each of the following? You may wish to review the chapter on chemical bonding and molecular geometry.

(a) XeO₂F₂

(b) KrF₂

(c) ${\text{XeF}}_3{}^{+}$

(d) ${\text{XeO}}_6{}^{\mathrm{4-}}$

(e) XeO₃

Basic solutions of Na₄XeO₆ are powerful oxidants. What mass of Mn(NO₃)₂•6H₂O reacts with 125.0 mL of a 0.1717 M basic solution of Na₄XeO₆ that contains an excess of sodium hydroxide if the products include Xe and solution of sodium permanganate?