Abeka Chemistry Chapter 10

What is meant by the designation 15-10-7 on a bag of fertilizer?

15% nitrogen, 10% P₂O₅ equivalent, and 7% K₂O equivalent

Write a balanced equation for the combustion of butane, C₄ H₁₀ (I).

2 C₄H₁₀(l) + 13 O₂(g) → 8 CO₂(g) + 10 H₂O(g)

Write a balanced equation showing the reaction of hydrogen and potassium.

2 K(s) + H₂(g) → 2KH(s)

About forty million tons of H₂SO₄ are produced in the United States annually. How many moles of H₂SO₄ is this?

4 x 10¹¹ mol

Write the balanced equation for the reaction occurring when baking powder is heated.

Ca(H₂PO₄)₂(s) + 2 NaHCO₃(s) →∆→ 2 CO₂(g) + 2 H₂o(g) + CaHPO₄(s) + Na₂HPO₄(s)

Write the formula for nitric acid.

HNO₃

What is the basis for the bleaching action of household bleach?

HOCl adds to double bonds, converting them to colorless single bonds.

Name the process used to synthesize ammonia commercially and write a balanced equation for the reaction.

Haber process;

Name three important nitrogen fertilizers and write their formulas.

any 3 of the following: ∙urea - (NH₂)₂CO ∙ammonia - NH₃ ∙ammonium sulfate - (NH₄)₂SO₄ ∙ammonium nitrate - NH₄NO₃ ∙ammonium dihydrogen phosphate - NH₄H₂PO₄

List three uses of nitrogen.

any 3 of the following: production of ammonia for fertilizers; inert atmosphere for some foods and reactive chemicals; manufacture of explosives and rocket fuels; fast-freezing of foods; refrigerating foods and biological specimens

List five comercial uses of sulfuric acid.

any 5 of the following: production of fertilizers, fibers, plastics, dyes, paints, and detergents; petroleum refining; metal refining; dehydrating agent

List five uses for sulfur. including its most important use.

any 5 of the following: synthesis of sulfuric acid (most important use); vulcanization of rubber; preparation of insecticides, fungicides, pharmaceuticals, gunpowder, dyes, photographic materials, and textiles

List three uses of phosphates.

any three of the following: fertilizers; acidity regulators and emulsifiers in food; baking powder; toothpastes; water softeners; crop-protection chemicals (pesticides); metabolism

List two important uses of hydrogen.

any two of the following: synthesis of ammonia; hydrogenation of vegetable oils; rocket fuel; oxyhydrogen torch; self-luminous items (tritum)

Which noble gas is the most common in the atmosphere?

argon

How is oxygen most often prepared commercially?

by distilling liquid air or by filtering air through a molecular sieve

Define nitrogen fixation

conversion of atmospheric nitrogen to compounds plants can use

What is one laboratory method of preparing hydrogen?

either of the following: electrolysis of water, reacting zinc with acid

Give five uses of phosphoric acid (H₃PO₄) and its salts.

fertilizers; acidity regulators and emulsifiers in foods; baking powder; toothpastes; water softeners; crop-protection chemicsl (pesticides); metabolism

How could you prepare O₂ (g) in the laboratory?

heat KClO₃(s) with MnO₂(s), react Na₂O₂ with water, or electrolyze water

Tell how you would prepare chlorine gas in the laboratory.

heat an alkali metal chloride salt with concentrated H₂SO₄ and MnO or react concentrated hydrochloric acid with manganese (IV) oxide

What is the most abundant element in the universe?

hydrogen

What is photosynthesis? Give the equation for the overall reaction if glucose is the product.

the process in which plants use energy from sunlight to convert CO₂(g) and H₂O(l) into O₂(g) and carbohydrates; 6 CO₂(g) + 6H₂O(l) → C₆H₁₂O₆(s) + 6 O₂(g)

What are the two major allotropes of phosphorus? Explain how their structures differ from each other.

white phosphorus, red phosphorus; White phosphorus is P₄ and tetrahedral in structure; red phosphorus is a polymer consisting of chains of P₄ subunits

Name the two most important allotropes of phosphorus. Which is more stable?

white phosphorus, red phosphorus; red phosphorus

How is phosphorus prepared? Write the balanced equation for this reaction.

∙Elemental phosphorus (P₄) is obtained from phosphate rock by heating it to more than 1000⁰C with coke (carbon) and silica sand (SiO₂). ∙2Ca₃(PO₄)₂(s) + 10 C(s) + 6 SiO₂(s) →∆→ 6 CaSiO₃(l) + 10 CO(g) + P₄(g)

List two uses for each of the halogens fluorine, chlorine, and bromine and two uses for iodine.

∙fluorine - fluoridation of water; toothpastes; manufacture of refrigerants, PTFE, and perfluorocarbons; nuclear fuel refining; glass etching; lasers ∙chlorine - bleaches and disinfectants; plastics; medicines; crop-protection chemicals ∙bromine - firefighting chemicals (halons); dyes and pharmaceuticals; perfluorocarbons; photographic emulsion; water purification ∙iodine - antiseptic; iodized salt; photographic emulsion; some refrigerants; lasers

List three uses of noble gases.

∙helium - lifting gas in balloons and airships; cryogenic coolant; diving mixtures; inert atmosphere for welding; diluent for gaseous anesthetics; lasers ∙neon - neon signs; airport runway lights; lasers ∙argons - incandescent light bulbs; inert atmosphere for metallurgy and welding; flushing O₂ from molten metals; lasers ∙krypton - airport runway lighting, high intensity flashlight bulbs ∙xenon - photographic flash tubes; arc lamps

List five uses of oxygen and two uses of ozone.

∙oxygen (any 5 of the following) - steel manufacture; medical uses; breathing apparatuses; oxyhydrogen and oxyacetylene torches (welding); oxidizer in liquid-fueled rockets; metabolism ∙ozone (any 2 of the following) - purification of drinking water; deodorizing air and sewage gases; bleaching textiles, waxes, and oils

What is PTFE? Give three uses of PTFE.

∙polytetrafluoroethylene (a polymer of tetrafluoroethene) ∙electrical insulators, high-temperature plastics, cookware, nonlubricated valves and bearings

Describe the Claus process of producing sulfur.

Answers will vary. H₂S (g) removed from petroleum and natural gas is burned, producing SO₂(g), which reacts with more H₂S(g) to form elemental fulfur: 2H₂S(g) + 3 O₂(g) →∆→ 2SO₂(g) + 2H₂O 2H₂S(g) + SO₂(g) →∆→ 3S(g) + 2H₂O(g)

How do safety matches differ from strike-anywhere matches?

Answers will vary. Safety matches need to be ignited by the friction on red phosphorous found on a special striking surface. Strike-anywhere matches have all the necessary components for ignition in the head of the match.

Differentiate between an oxide, a peroxide, and a superoxide.

Answers will vary; an oxide contains the O²⁻ ion, a peroxide contains teh O₂²⁻ ion, and a superoxide contains the O₂⁻ ion.

Though both oxygen and nitrogen are diatomic gases, nitrogen is far less reactive than oxygen. Why?

Answers will vary; nitrogen has a strong triple bond whereas oxygen has a double bond.

Write the formula for cesium superoxide.

CsO₂

How would you prepare NO₂ in a laboratory?

Cu(s) + 4 HNO₃(aq) → Cu(NO₃)₂(aq) + 2 NO₂(g) + 2 H₂O (l)

Write a balanced equation for the combustion of the hydrocarbon heptane. C₇H₁₆ (I).

C₇H₁₆(l) + 11 O₂(g) → 7 CO₂ (g) + 8 H₂O(g)

Describe what happens to sulfur as it is heated from room temperature to about 250°C; mention the various allotropes encountered.

Heating rhombic sulfer to above 96⁰C converts it to monoclinic sulfur, which melts at 119⁰C to forma pale yellow liquid. Viscosity increases with continued heating to above 150⁰C-187⁰C, and the color changes to reddish brown; by 187⁰C it is very viscous. Continued heating to above 250⁰C reduces the viscosity once again.

Write a balanced equation showing the reaction of hydrogen and fluorine.

H₂(g) + F₂(g) → 2HF(g)

Write a balanced equation showing the reaction of hydrogen and sulfur.

H₂(g) + S(s) → H₂S(g)

Write the formula for sulfuric acid.

H₂SO₄

Write the formula for phosphoric acid.

H₃PO₄

Write the formula for ammonia.

NH₃

Write the formula for ammonium nitrate.

NH₄NO₃

How would you prepare N₂O in a laboratory?

NH₄NO₃(s) →∆→ N₂O(g) + 2H₂O(g)

Write the formula for sodium nitrite.

NaNO₂

Write the formula for sodium hypochlorite.

NaOCl

Write the formula for ozone.

O₃

Give the equations showing the steps involved in synthesizing sulferic acid by contact process.

Pg 166 #5

Give equations showing the commercial methods for preparation of the halogens (F₂, Cl₂, Br₂, and I₂).

Pg 173 #1

List two uses of nitrous oxide.

any 2 of the following: anesthetic in minor surgery; propellant for food products (whipped cream); oxidizer in high-performance engines

What is hydrogenation? Why is it used in some food products?

addition of hydrogen to double or triple bonds; makes oils more solid and thus more suitable for certain food

What is an allotrope?

a form of an element that differs in properties from but exists in the same physical state as another form of the element

What is the major source of helium?

natural gas

What industrial chemical is produced throught the Ostwald process?

nitric acid

What is an allotrope?

one of two or more forms of the same element that differ in their properties but exist in the same physical state

Sand is the oxide of what element?

silicon

What is the most important commercial method of preparing hydrogen in the U.S.?

steam reforming

List four uses of phosphorus.

sythesis of phosphoric acid and other phosphorus compounds; manufacture of matches and specialized miltary ammunition