There are a large number of objects around us which we can see and feel.
One of the most important concept come out from Dalton’s atomic theory was that of relative atomic
mass or relative atomic weight
The atomic mass unit
Mole is a chemical counting Sï‰ unit and defined as follows
The atomic mass of an element expressed in gram is called gram atomic mass of the
element.
The molecular mass of a substance expressed in gram is called the gram-molecular mass of the
substance
According to him elements combine in a simple ratio of atoms, gases combine in a simple
ratio of their volumes provided all measurements should be done at the same temperature
and pressure
Y-map : Interconversion of mole - volume, mass and number
of particles
Here we are going to find out the percentage of each element in the compound by knowing
the molecular formula of compound
We have just seen that knowing the molecular formula of the compound we can calculate percentage
composition of the elements. Conversely if we know the percentage composition of the elements
initially, we can calculate the relative number of atoms of each element in the molecules of the
compound. This gives us the empirical formula of the compound
It is the process in which two or more than two substances interact with each other where old
bonds are broken and new bonds are formed
Once we get a balanced chemical equation then we can interpret a chemical equation by following ways
Now again consider decomposition of
This analysis is very much important for quantitative analysis point of view. Students are advised to
clearly understand this analysis
The reactant which is consumed first and limits the amount of product formed
in the reaction, and is therefore, called limiting reagent
Step :1 Divide the given moles of reactant by the respective stoichiometric coefficient of that reactant.
Step :2 See for which reactant this division come out to be minimum. The reactant having minimum
value is limiting reagent for you.
POAC is conservation of mass. Atoms are conserved, moles of atoms shall also be conserved in a chemical
reaction (but not in nuclear reactions.)
AVERAGE/ MEAN ATOMIC MASS
Let us do a comparative study of oxidation and reduction
It is important to note that to calculate individual oxidation number of the element in its compound one should
know the structure of the compound and use the following guidelines
In order to determine the exact or individual oxidation number we need to take help from the structures of the
molecules. Some special cases are discussed as follows
Fractional oxidation number is the average of oxidation state of all atoms of element under examination and the
structural parameters reveal that the atoms of element for whom fractional oxidation state is realised a
actually present in different oxidation states.
Oxidising agents are those compounds which can oxidise others and reduce itself
during the chemical reaction. Those reagents in which for an element, oxidation number
decreases or which undergoes gain of electrons in a redox reaction are termed as
oxidants.
HOW TO IDENTIFY WHETHER A PARTICULAR SUBSTANCE
IS AN OXIDISING OR A REDUCING AGENT
All balanced equations must satisfy two criteria
A mixture of two or more substances can be a solution
The number of moles of a solute dissolved in 1 L (1000 ml) of the solution is known as the molarity
of the solution
The number of moles of solute dissolved in1000 gm (1 kg) of a solvent is known as
the molality of the solution
The ratio of number of moles of the solute or solvent present in the solution and the total number of
moles present in the solution is known as the mole fraction of substances concerned
can behave both like oxidising and reducing agent in both the mediums (acidic and basic).
When the solute is present in very less amount, then this concentration term is used. It is defined as the number
of parts of the solute present in every 1 million parts of the solution
Strength of Oleum
