C12 + C13

Question 1

Describe the manufacture of sulfuric acid by the Contact process

Answer 1

Step 1: Sulfur is burned in the presence of oxygen to produce sulfur dioxide

Step 2: Sulfur dioxide is mixed with excess air and passed over a vanadium oxide catalyst forming sulfur trioxide. the conditions must be high temperature, excess of air, exothermic, and lower pressure (remember HEEL)

Step 3: Sulfur trioxide is dissolved in concentrated sulfuric acid to form oleum (a thick, fuming liquid)

Step 4: Water is added to the oleum to make concentrated sulfuric acid

Question 1

Name the use of sulfur in the manufacture of
sulfuric acid

Answer 1

The manufacture of sulfuric acid takes place in a process called the CONTACT PROCESS.

The raw materials required are sulfur, air and water. Sulfur can be obtained from sulfide ores, or extracted as hydrogen sulfide (from petroleum or natural gas) and separated.

Question 2

chemical formulas for the steps of the contact process

Answer 2

look at the syllabus! memorize!

Question 3

describe the manufacture of lime (calcium oxide) from limestone (calcium carbonate)

Answer 3

Calcium oxide (lime) is manufactured by thermally decomposing calcium carbonate (limestone):

MEMORISE THE CHEMICAL FORMULA/EQUATION

calcium carbonate ——–> calcium oxide + carbon dioxide

Question 4

describe the use of limestone

Answer 4

it is used to treat acidic soil and industrial waste in order to neutralise it. The sulfur dioxide that factories produce are reacted with calcium oxide so that it doesn’t mix with the air and cause acid rain. limestone, lime, and slaked lime are all basic!

Question 5

describe the thermal decomposition of calcium carbonate (limestone)

Answer 5

When heated above 840°C, calcium carbonate (limestone) decomposes, releasing carbon dioxide gas and leaving behind calcium oxide (lime) – a white solid