7
Which row describes the properties of fluorine?
Colour State at r.t.p
a) Yellow gas
b) Green gas
c) Brown liquid
d) Brown gas
(a)
Define Oxidation and Reduction
Oxidation- The loss of electrons
Reduction is the gain of electrons
A solution of lithium halide and a halogen are mixed together. A reaction occurs and the mixture darkens in colour.
What is present in the reaction mixture?
(a)Bromine and lithium chloride
(b)Bromine and lithium fluoride
(c)Chlorine and lithium iodide
(d)Chlorine and lithium fluoride
(c)
which statement about electrolysis is correct?
-Electrons move through the electrolyte from the cathode to the anode
Electrons move towards the cathode in the external circuit
Negative ions move towards the anode in the external circuit
Positive Ions move through the electrolysis towards the anode during electrolysis
Electrons move towards the cathode in the external circuit
Explain, in terms of the reactivity of halogens, why aqueous iodine does not react with aqueous potassium chloride.
`Chlorine is more reactive than iodine / iodine is less reactive than chlorine.
Give two uses of zinc.
-Roofing
-Coinage
-Cells
-Electroplating / as an electrode in electrolysis
-Sacrificial protection / galvanising / preventing iron from rusting
-Making brass or making alloys
Solid lead (II) bromide is heated until molten. The molten lead (II) bromide then undergoes electrolysis
Which substances are formed at each electrode
Anode- Bromine
Cathode- Lead
What is the correct balanced symbol equation for the overall reaction in a hydrogen oxygen fuel cell
2h^2+O^2-->2H^2O
When aqueous lithium bromide is electrolysed, a colourless gas is formed at the negative electrode and the solution becomes alkaline.
Explain these observations and include an equation in your explanation.
When lithium bromide is aqueous and not molten, there are H+ and OH- ions that need considering.
Hydrogen is less reactive than lithium so hydrogen ions will be discharged at the cathode instead of lithium, gaining electrons and forming hydrogen gas.
Bromide ions will be discharged at the anode, leaving lithium and hydroxide ions in solution to form lithium hydroxide.