Laws Of chemical Combination/Multiple Proportion/ molarity

Laws of Chemical Combination:

Law of Conservation of Mass:

During physical and chemical change, the mass of reactant and product is always remains same.

AgNo3+Hcl---------------àAgcl+HNo3

Laws of constant composition:

A chemical compound is always formed from the same element and they do so in fixed proportion by mass.

For example:

C+O2---àCO2

C=12

O=32

12:32=3:8

And CaCO3---à CaO + CO2

12:32=3:8

Laws of Multiple Proportions:

When two elements combines to form two or more than two compound than mass of one element which combines with the fixed mass of other bear a simple whole number ratio to one another.

N2O4, NO2, N2O3, NO2

N2O4	NO2	N2O3
N=28	N=14	N=28
O=64	O=32	O=48

Now we need to fixed the mass of one elements and other will bear a simple whole number ratio

So we can divide N2O4, N2O3 by 2 leaving NO2 and oxygen will bear 32:32:24

Or 4:4:3

Gay Lusaac’s Law:

When the gases react together to produce the product than they do so in a particular volume ratio under similar temperature and pressure condition.

Avogadro’s Law:

All equal volume of gases contains same number of molecules under same temperature and pressure conditions.

Applications of Avogadro’s law:

Molecular mass=2*vapour density

Molecular mass= mass of 22.4 L of gas

Some Concepts related to moles in solution:

1. Mass percent:

Mass of solute/Mass of solution

2. Strength: Mass of solute/ Volume per litre of the solution

3. Molarity: Number of moles of the solute / Volume per litre of the solution

4. Molality: Number of Moles of the solute/ Solvent in Kg

5. Normality: Gram equivalence/Volume of the solution

Gram equivalence : Mass of X/Equivalent Wt.

Equivalent Weight: Molecular Weight /Valency

So in conclusion:

NV=Mass of X / Mol. Wt/ X factor