Elements from the sea(ES) Flashcards
What factors can affect the position of equilibrium?
Concentration, pressure and temperature
What is meant by ‘dynamic equilibrium’
A reversible reaction which takes place in a closed system. The rate of the foward reaction is equal to the rate of the backwards reaction. Concentrations remain constant
What happens to the position of eqm if temperature:
* Increases
* Decreases
- Increases=direction of the endothermic reaction~increase in amount of products of endo reaction
- Decreases=direction of the exothermic reaction~increase in amount of products of exo reaction
What happens to the position of eqm if the pressure
-Increases
-Decreases
-Increases=Side with fewer gas molecules
-Decreases=Side with more gas molecules
Why don’t catalysts affect the position of eqm?
Catalysts only increase the rate of the foward and backward equation equally. Therefore they don’t affect the position of eqm
What is the other name for group 7 elemants?
Halogens
What bond is formed between two group 7 elements?
Covalent
What is the appearance of Fluorine,Chlorine, Iodine and bromine at room temperature?
- Fluorine~pale yellow gas
- Chlorine~green gas
- Bromine~dark red volatile liquid
- Iodine~shiny black solid
What happens as you go down group 7?
- Becomes darker in colour
- Melting and boiling points increase
- Become less volatile
Are halogens more soluble in water or organic solvents e.g. hexane
Orgainc solvents~this means that in organic solvents halogens have a much more distinct colour
What is the reaction between a halogen and a halide?
Displacement reaction
Why does a displacement reaction happen?
A halogen displaces a less reactive halogen from the compound
What is the test for halide ions?
Add silver nitrate solution then ammonia to distinguish between the halides
What is precipitate of chloride,bromide and iodide when silver nitrate is added?
- Chlorine~White
- Bromine~Cream
- Iodine~Pale yellow
What is the result of cyclohexane with chlorine,bromine and iodine?
- Chlorine~TL pale green and BL colourless
- Bromine~TL orange and BL pale orange
- Iodine~TL violet and BL brown
What is the results of potassium bromide with chlorine,bromine and iodine?
- Chlorine~pale yellow
- Bromine and iodine~no reaction
What is the results of potassium iodide with chlroine,bromine and iodine?
- Chlorine and bromine~TL violet and BL pale brown
- Iodine~No reaction
What can a redox reaction be defined by?
- Electrons
- Oxidation state
- Oxygen
What happens if an ionic compound is melted or dissolved?
Charged ions are free to move around and carry a current
What is produced at the cathode?
Metal
What is produced at the anode?
Non-metal, apart from hydrogen
What are the three stages involved in extracting bromine from the sea?
- Oxidation of bromide to bromine~acidified using sulfuric acid then excess chlroine is used to displace bromine
- Bromine vapours are removed
- Bromine is reduced to from hydrogen bromide
Why does oxidising power decrease down group 7?
- The size of the atom increases
- Ability to attract electrons decreases due to shielding and a greater atomic radius
- The attraction between the positive nucleus and outer electrons decreases
Why does thermal stability of hydrogen halides decrease down group 7?
- Covalent bonds are weaker
- Broken more easily upon heating
- Bonds are weaker as atoms get larger
- Attraction between the outer electrons and the nucleus is weaker
