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A Tutorial on Stoichiometry: Notes, Figures and Problems with Solutions

Target Audience: These notes on Atomic Structure are meant for college freshmen, or high school students in Grades 11 or 12.

They might be of use to Indian students preparing for the ISC or CBSE Class 12 Examinations, IIT JEE (main and advanced), AIEEE; students from across the world preparing for their A Level Examinations, IB (International Baccalaureate) or AP Chemistry.

This compilation of notes has been prepared by Ayushi Patel of IIT Gandhinagar.

Summary and Outline of Notes: Here's a quick recap of the outline of topics which were covered in this tutorial

1.    Introduction to Stoichiometry                                                                                                                                           

Number of moles :  weight of the given substance

                                            Molecular weight      

The reaction involving exchange of electrons is called redox reaction. For eg,

 Zn  →  Zn+2  + 2e-1

Above reaction is oxidation reaction,since it involves loss of electrons.

Cl + e-1 → Cl-1   .

This reaction is reduction reaction ,since it involves addition of electrons.

The reaction that not involves any exchange of electrons is called non-redox reaction.

2. Balancing Redox Reactions

Always work with balanced equation in Stiotiometry because balanced equation represents the qualitative as well as quantitative information about a reaction.

3. Limiting and Excess Reagent

Limiting Reagent :  

It is the substance in a reaction that gets consumed first while completing the reaction,it limits the formation of product.

Excess Reagent :

The substance which is left out when reaction is complete is called excess reagent.

4. Molarity, Molality, N Factor, Normality

5. A Quick Look at some of the questions you will solve. The tutorial above, also teaches you how to solve problems of the following kind (these are only a few of the problems):

If the percentages of hydrogen,carbon in a compound is 10.22, 59.81 %,  and remaining oxygen.Find the true molecular formulae of that compound if it has molecular weight between 100 and 110 g.

How many moles and mass of KMnO4  is required to react with oxalic acid in order to produce carbon di oxide at 500 C and 2 atm pressure of 4 L ?

HCl solution of density 1.18 gml-1 is identified to be 82 % by weight .

i)Calculate the molarity of acid .

ii)Calculate the volume of HCl needed to make 2L and 0.3 M of HCl .

Hot water is reacted with aluminium .How much weight of aluminium will be converted to Aluminium  oxide if 36 g of steam was taken.

When Chromium trioxide is reacted with HCl ,Chlorine gas is released at 2 L STP .

i)Find the mass of chromium trioxide reacted

ii)Volume of HCl used if the HCl used is 10 % by weight .

Take density = 1.18 gmL-1        

When BaCO3 reacts with HCl carbon dioxide is formed ,the density of HCl is 1181 kg/m3 and volume of HCl is 400 mL .Find out which reactant is the limiting reagent ,calculate the weight of the limiting reagent left and amount of CO2  released considering room temperature ,1 atm pressure and 50g of BaCO3  taken .