Chapter 4 - acids, bases and redox Flashcards
Natural state elements
All elements in their natural state have an oxidation number of 0
Oxidation number of molecules
The sum of the oxidation numbers of the atoms in a molecule is 0
Ion oxidation numbers
Oxidation numbers of the components of an ion sum to the charge of the ion
1.
The oxidation numbers of of elements in groups 1,2,3 are +1,+2,+3 respectively
2.
The oxidation number of fluorine is always -1
3.
The oxidation number of hydrogen is usually +1
4.
The oxidation number of oxygen is usually -2
5.
The oxidation number of chlorine is usually -1
Reduction is …(3)
Gain of electrons
Loss of oxygen (in some cases)
Decrease in oxidation number
Oxidation is…(3)
Loss of electrons
Gain of oxygen (in some cases)
Increase in oxidation number
An acid is …(2)
A proton donor
Releases H+ ions when dissolved
A base is …
An alkali is…
(2)
A proton acceptor
An alkali is a soluble base which released OH- ions in water
Acid + metal oxide —>
Acid + metal hydroxide —>
Acid + metal —>
Acid + metal carbonate —>
Salt + water
Salt + water
Salt + hydrogen
Salt + water + carbon dioxide
Method for making a standard solution
- Measure a set mass of solid
- Add to a beaker then add approx. 40% of required solvent
- Add to a volumetric flask through a funnel then using distilled water rinse funnel and beaker into volumetric flask
- Fill to the line then invert twice
Method for doing an acid-base titration
1) Add a measured volume of one solution to a conical flask using a pipette (usually the base)
2) add a bit of the other to the burette and swill, empty and refill, making sure the nozzle is filled
3) add indicator to the conical flask the add the bursts solution roughly until there is a colour change (rough titration)
4) repeat being very precise and taking results until there are 2 Concordant titre results
