Topic 9
No description yet. This curated deck is ready for daily study.
Card preview (18)
What is oxidation?
• gain of oxygen, gain of hydrogen and loss of electrons
What is reduction?
The loss of hydrogen and oxygen and gain of electrons
What is O.S of elements?
0
What is the O.S. of oxygen in a compound?
-2 except in peroxides it is -1
What is the O.S. of H ?
+1 except in metal hydrides it is -1
What is the O.S. of a neutral compound?
O
Work out the O.S. of S in SO42-?
+6
Work out the O.S. of Cr in K2Cr2O7
+6
What is the rule for O.S. in polyatomic ions?
The sum of all O.S. should equal the charge on the ion
How to write net ionic equations?
• Write the molecular equation • Write the full ionic equation • Cancel out spectator ions
How to calculate redox titrations for acid solutions?
• Balance for atoms other than H or O • Balance for O by adding H20 • Balance for H by adding H+ • Balance for the charges by adding electrons
Balance the equation Fe2+ + MnO4- —FE3+ + Mn2+
What does the reactivity series tell us?
The ease the metals undergo oxidation ( top being more likely to be oxidised)
What can metals above hydrogen do?
the displace the H+ ions to form H2
What does in an increase for an oxidation state of a metal show?
The element is oxidised ( it is a reducing agent)
What are the features of electrolytic cells?
• split ionic compounds into their constituent elements through an electrical current • has the positive electrode being the anode and the negative being the cathode • from electrical to chemical energy • endothermic • non spontaneous
How is the electrical current conducted?
• electron flow in the wires and the movement of ions in the electrolyte
What are the features of the voltaic cell?
• Spontaneous redox reaction • positive electrode is the cathode and the negative electrode is the anode • from chemical to electrical energy • electrons flow from anode to cathode