# Class 9 Chemistry Formulae

Sep 4 • Notes • 3355 Views • 3 Comments on Class 9 Chemistry Formulae

Class IX, the pre-board class keeps the foundation of class XI, syllabus being similar. Hence one should start its preparation at the earliest. Oureducation.in will be helping you in doing so. Keeping notes is easy when every formula is available on a single page. Here are some formulae from two very important chapters, Thermodynamics and Solutions.

## CHAPTER- Thermodynamics

Formula 1:
Temperature (in K)= Temperature(in degree Celsius) +273.15

Formula 2:
(Celsius x 9/5) + 32 = Fahrenheit

Formula 3:
Internal energy: The total energy with a system.
i.e.U = Ee + En + Ec + Ep + Ek + ——

U = U2 – U1 or UP – UR & U is state function and extensive properly. If U1 > U2, energy is released

Formula 4:
First Law of Thermodynamics: It is law of conservation energy. Energy can neither be created not destroyed, it may be converted from one from into another.

Formula 5:
Mathematically ΔU = q + w, w = –p. ΔV (work of expansion)
ΔU = q – p. ΔV or q = ΔU + p. ΔV, q,w are not state function,
but ΔU is state function

Formula 6:
Enthalpy (H): At constant volume ΔV = 0→q(volume)  =ΔU
So H = U + p.ΔV, q(pressure)= H2 H1 = ΔH
ΔH = ΔU + P. ΔV

Formula 7:
Relationship between q(pressure), q(volume) i.e. ΔH& ΔU
It is ΔH = ΔU+ Δng.RT or q(pressure) = q(volume) + Δng.RT

Formula 8:
Hess’s Law of constant heat summation: The total amount of heat change is
same whether the reaction takes place in one step or in several steps.
i.e. ΔH = ΔH1 + ΔH2 + ΔH3 + ——–

Formula 9:
Gibb’s free energy (G): defined as G = H – T.S & G = H – T. S (Gibb’s Helmholts equation) it is equal useful work i.e. – G = W(useful) = W(max.), If G = -ve, process is spontaneous.

## CHAPTER- Solutions

Formula 1:
Mass percentage of a solution=(Mass of solute/mass of solution)*100

Formula 2:
Volume percentage of a solution=(Mass of solute/volume of solution)*100

Formula 3:
Number of moles(n)=Mass of substance/molar mass

Formula 4:
Number of moles(n)= Given number of particles/Avogadro number

Formula 5:
Mass=Molar mass* Number of moles

Formula 6:
Number of atoms=(Given mass/molar mass)* Avogadro number

You may also like to visit:
Formulae of Class X Physics from Electricity and Magnetic Effects of Current

### 3 Responses to Class 9 Chemistry Formulae

1. Vandana Singh says:

9th

2. Vandana Singh says:

9th