Summary Acids and bases Introduction

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Acids and bases
For any confusion view pdf notes (from group)




Terminology
Acid: Substance that produces Hydrogen ions in water (Proton Donor)
Base: Substance that produces hydroxide ions in water.(Proton Acceptor)
Strong acids: ionize completely in water
Weak acid: ionize incompletely in water
Strong Bases: dissociates completely in water
Weak Bases: dissociates incompletely in water
Concentrated Acid/Base: Contain a large amount of acid/base in proportion to the
volume of water
Dilute Acid/Base: Contain a small amount of acid/base in proportion to the volume of
water
Ampholytic Substance: Substance which can act as an acid or a base
Hydrolysis: The reaction of a salt with water.
Kw: The equilibrium constant for the ionisation of water
Auto-ionisation of water: The reaction of water with itself to form H3O+ and OH ions.
Equivalence point: The point at which the acid or base has completely reacted with the
other acid or base.
End point: The point where the indicator changes color and the acid has neutralised the
base.
Neutralization: When an acid is added to a base to form salt and water.
Titration: A chemical process to determine the concentration of an unknown acid or
base by using a standard solution whose concentration is known.
Standard solution: The solution of which the exact concentration is known




Titration

A chemical process to determine the concentration of an unknown acid
or base by using a standard solution whose concentration is known.


Requirements of a standard solution
high grade of purity
preferably a solid
not be hygroscopic or worn.

, Aim
To standardize a solution of an unknown acid or base against a standard soltution
whose concentration is known.




Apparatus
Pipette (Used to measure exact volume)
Pipette filler
Burette (Used to measure exact volume)
Conical Flask
White tile or paper
Funnel
Glass beaker
Retort stand
Wash bottle
Mass balance




Precaution
Wear a lab coat, gloves and safety glasses
Handle acids and bases carefully as they are caustic and corrosive substances.
Avoid contact of acids or bases with the skin or clothes.




Method

Preparation of a standard solution

The solution of which the exact concentration is known




How to prepare a standard solution

Calculate the mass required and weigh it on a mass balance
Pour the solid base into a known volume volumetric flask.
Slowly add water with constant swirling to speed up dissolution rate.
Distilled water is used because it is de-ionized and will not affect base in the flask.
Add water drop wise until it reaches the mark on the conical flask.