The chlor-alkali Industry Flashcards
The chlor-alkali industry the exploitation of the following equation:
2NaCl (aq) + 2H20 (l) —> 2NaOH (aq) + H2 (g) + Cl2 (g)
While the starting substance is something as simple as concentrated NaCl solution (brine), the ____ of this process play a key role in other industries and
are incredibly useful.
products
What are the uses of Cl2? (4)
- Purify water
- Disinfectant
- Production of HOCl (used in drinking water)
- Production of food, paper, paints, PVC etc
What are the uses of NaOH? (4)
- Make soap and cleaning products
- Purify bauxite
- Make paper
- Make Rayon
What are the uses of H2? (3)
- Saturation of double bonds – making margarine
- Making Ammonia
- Fuel Cells
As with most electrolytic processes, the reaction taking place is non-spontaneous and therefore thermodynamically unfavoured. What does this mean?
This means that if the products of this process were to meet each other, they would recombine spontaneously. This poses an economic and a safety risk (H2 and Cl2 recombine explosively) and so over the years, several different cells have been designed to carry out this process, and inso doing, keep the products separate from each other.
Advantage of diaphragm cell?
Low energy requirement
Disadvantages of diaphragm cell? (4)
- Abestos is toxic and needs to replaced regularly
- NaOH contaminated with NaCl needs to be repurified
- Cl2 contaminated with O2
- Not very cost effective
Advantage of membrane cell? (4)
- NaOH is more pure than in diaphragm cell
- Most energy efficient
- No toxic components
- Cheapest cell to run
Advantage of mercury cell?
Very pure Cl2 gas produced
Disadvantage of mercury cell? (3)
- Mercury is toxic and inevitably escapes to products and the environment
- High energy requirements
- NOT REALLY USED ANYMORE
What is brine?
A concentrated aqueous solution of sodium chloride (NaCl).
