Sulfur

Question 1

What are the sources of sulfur? (4)

Answer 1

Found as an element, in large underground beds
Found around the rims of volcanoes.
It occurs in metal ores
e.g. lead sulphide
Sulphur compounds also occur naturally in the fossil fuels
e.g. coal

Question 2

What are the uses of sulfur? (2)

Answer 2

In car batteries as electrolyte

In manufacture of sulphuric acid (through Contact process)

Question 3

What are the uses of sulfur dioxide? (2)

Answer 3

Manufacture of sulphuric acid
As a food preserver; kills bacteria
As a bleach in the manufacture of wood pulp for paper

Question 4

Describe the Contact Process (4)

Answer 4

Sulphur is first burned in air producing sulphur dioxide
It is then mixed with more air and passed over four separate beds of catalyst, Vanadium (V) oxide, at 450°C to form sulphur trioxide
It is then dissolved in concentrated sulphuric acid forming a thick fuming liquid called oleum
It is then mixed carefully with water to form concentrated sulphuric acid

Question 5

What are the conditions required for the Contact Process? (3)

Answer 5

Catalyst: Vanadium (V) oxide
Temperature: 450°C
Pressure: 2atm

Question 6

What are the uses of concentrated sulfuric acid? (3)

Answer 6

for making detergents
as a catalyst
as a dehydrating agent

Question 7

What are the uses of diluted sulfuric acid? (4)

Answer 7

For making fertilizers.
To treat metals to remove oxidisation before painting.
For anodising aluminium.
As an acid in car batteries.
For manufacturing paints, dyes and fibres.
As a common laboratory reagent

Question 8

What are the features of concentrated sulfuric acid? (3)

Answer 8

powerful dehydrating agent: take water from many substances
Used to dry gases (except ammonia)
Powerful oxidising agent

Question 9

What are the features of dilute sulfuric acid? (2)

Answer 9

typical strong dibasic acid: two replaceable hydrogen atoms may produce 2 series of salts – normal and acid salts

Question 10

What is the catalyst in the contact process?

Answer 10

Vanadium (V) oxide

Question 11

What temperature is used in the contact process?

Answer 11

450°C

Question 12

What pressure is used in the contact process?

Answer 12

2atm

Question 13

Why do we want to form oleum in the Contact Process?

Answer 13

When sulfur trioxide reacts with water, a fine mist of sulfuric acid forms which does not condense easily.

Question 14

What does an increase in temperature lead to and why?

Answer 14

Reaction is exothermic
=> yield of sulfur trioxide decreases with increasing temp.
Too low temp, rate of reaction low => compromise

Question 15

What is the effect of the catalyst on the equilibrium?

Answer 15

Nothing - catalyst works equally

Question 16

Write equations involved in Contact Process?

Answer 16

.