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OCR A-Level Chemistry Salters B > Elements from the Sea > Flashcards

Flashcards in Elements from the Sea Deck (17)
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1

Appearance of the halogens at room temperature

-Fluorine: pale yellow gas
-Chlorine: green gas
-Bromine: dark red volatile liquid
-Iodine: black solid, sublimes to purple vapour

2

Trends going down group 7

-Become darker in colour
-Melting and boiling point increase
-Change from gases to liquids to solids at room temperature
-Become less volatile

3

Oxidation

-Loss of hydrogen
-Loss of electrons
-Increase in oxidation state

4

Reduction

-Gain of hydrogen
-Gain of electrons
-Decrease in oxidation state

5

Products of electrolysis at the cathode

-Hydrogen if the metal comes from group 1 or 2 or is aluminium
-Metal for all other salts
-Hydrogen is made on the electrolysis of acids

6

Products of electrolysis at the anode

-Halogen if the salt is a halide
-Oxygen if the salt is a sulphate or nitrate
-Oxygen is made on electrolysis of hydroxides

7

Anode and cathode, oxidation and reduction

Reduction happens at the cathode

Oxidation happens at the anode

8

Dynamic Equilibrium

-Concentrations of reactions and products stay constant
-Forward and reverse reactions are both happening
-The rate of the forward and reverse reactions are equal to each other

9

Atom economy

Relative formula mass of the desired product/Relative formula mass of all reactants used

10

Thermal stability down group 7

The thermal stability down group 7 increases because the bond strength between hydrogen and the halogen decreases as you go down group 7

11

What happens when halides are heated in a lab

-Hydrogen fluoride isn't broken down into hydrogen and fluorine
-Hydrogen chloride isn't broken down into hydrogen and chlorine
-Some bromine gas is made when hydrogen bromide is strongly heated
-Large amounts of iodine are made if a red hot needle is plunged into hydrogen iodide

12

Acidity in group 7

Apart from HF, all the hydrogen halides fully dissociate

13

Halides reaction with sulphuric acid

-Hydrogen fluoride and hydrogen chloride do not react
-Hydrogen bromide makes sulphur dioxide, SO2
-Hydrogen iodide makes hydrogen sulphide, H2S

14

Le Chatelier's Principle

If a system is at equilibrium and a change is imposed, the system will oppose this change

15

Effect of concentration on equilibrium

-Increasing the concentration of the reactants will cause equilibrium to shift to the side of the products
-Decreasing the concentration of the reactants will cause equilibrium to shift to the side of the reactants

16

Effect of pressure on equilibrium

-Increasing the pressure will cause equilibrium to shift to the side with fewer moles of gas
-Decreasing the pressure will cause equilibrium to shift to the side will more moles of gas

17

Effect of temperature on equilibrium

If endothermic:
-Increasing the temperature will cause equilibrium to shift to the products side
-Decreasing the temperature will cause equilibrium to shift to the reactants side

If exothermic:
-Increasing the temperature will cause equilibrium to shift to the reactants side
-Decreasing the temperature will cause equilibrium to shift to the products side