Unit notes and practice questions
Everything here is for unit 3 of the Grade 12 Chemistry textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
The cards filed under this chapter on the Grade 12 Chemistry page. Open one at a time.
When you use it
Use these sequential steps to write the chemical equations for the industrial production of sulfuric acid.
Watch out
SO3 is dissolved into concentrated H2SO4 to make oleum (H2S2O7), never directly into water.
Drafted from Grade 12 Chemistry, pages 136-213, then checked twice before it went up
When you use it
Use this reaction sequence to describe the production of sodium carbonate (Na2CO3) and identify its major by-product.
Watch out
The overall raw materials are CaCO3 and NaCl, while CaCl2 is the main by-product and NH3 is recycled.
Drafted from Grade 12 Chemistry, pages 136-213, then checked twice before it went up
When you use it
Use this rule when describing the laboratory or industrial dilution and handling of concentrated sulfuric acid.
Watch out
Never add water to concentrated sulfuric acid. Always add acid slowly to water because the dissolution is violently exothermic.
Drafted from Grade 12 Chemistry, pages 136-213, then checked twice before it went up
| Fertilizer | Raw Materials | Synthesis Reactions |
|---|---|---|
| Urea | , | |
| DAP | , |
When you use it
Use this table when writing industrial preparation reactions for nitrogen-based fertilizers like urea and diammonium hydrogen phosphate.
Watch out
Urea synthesis forms ammonium carbamate as an intermediate before dehydrating to urea.
Drafted from Grade 12 Chemistry, pages 136-213, then checked twice before it went up
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
In the Haber-Bosch process for industrial ammonia production, which substance is used as a catalyst?
Answer: C Iron particles
Why
In the Haber-Bosch process, nitrogen and hydrogen gases are reacted in a chamber containing iron particles (or lined with iron) at 300 to 500 °C and 15 to 25 MPa pressure.
Question 2
What is the percentage of nitrogen content in solid urea fertilizer?
Answer: C 46%
Why
Urea is a widely used solid fertilizer that has a high nitrogen content of 46%.
Question 3
Which catalyst is used in the Contact process to convert sulfur dioxide (SO2) into sulfur trioxide (SO3)?
Answer: B V2O5
Why
In Step 2 of the Contact process, the conversion of SO2 to SO3 is carried out at 400 °C in the presence of a V2O5 (vanadium pentoxide) catalyst.
Question 4
About half of the total world production of sodium carbonate is used in the manufacturing of which product?
Answer: A Glass
Why
About 50% of all sodium carbonate produced is used in the manufacturing of glass, where it acts as a flux in the melting of silica.
Question 5
Under laboratory conditions, pure nitric acid is prepared by heating which mixture below 200 °C?
Answer: B Potassium nitrate and concentrated sulfuric acid
Why
Laboratory preparation of nitric acid involves heating potassium nitrate (KNO3) and concentrated sulfuric acid (H2SO4), where the less volatile acid displaces the more volatile nitric acid.
Question 6
In Step 1 of the Ostwald process, ammonia is burned in excess oxygen over a platinum catalyst to produce which primary gas?
Answer: B Nitric oxide (NO)
Why
In Step 1 of the Ostwald process, ammonia is catalytically oxidized to produce nitric oxide (NO) and water: 4NH3 + 5O2 → 4NO + 6H2O.
Question 7
Which group of synthetic pesticides has a chemical structure based on the plant alkaloid Physostigma venenosum?
Answer: C Carbamates
Why
Carbamates are carbamic acid derivatives whose chemical structures are based on the plant alkaloid Physostigma venenosum.
Question 8
What is the main by-product formed in the Solvay process for manufacturing sodium carbonate?
Answer: A Calcium chloride (CaCl2)
Why
The overall Solvay process reaction is CaCO3 + 2NaCl → Na2CO3 + CaCl2, making calcium chloride the primary by-product.
Question 9
In standard urea-ammonium nitrate (UAN) liquid solutions, what percentage of the actual nitrogen is formulated as amide nitrogen?
Answer: D 50%
Why
All common UAN solutions are formulated so that 50% of the total actual nitrogen is from amide (from urea), 25% from ammonium, and 25% from nitrate.
Question 10
In Step 3 of the Contact process, sulfur trioxide is absorbed into 98% sulfuric acid to produce oleum. What is the chemical formula of oleum?
Answer: B H2S2O7
Why
Oleum (fuming sulfuric acid) is formed by the reaction SO3 + H2SO4 → H2S2O7.
The app holds 12 questions on this unit, marked as you go. These are the first 10.
Unit 3 runs from page 136 to page 213 of the Ministry of Education edition.
Ministry of Education edition, English, 298 pages
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