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Mole Concept and Stoichiometry – Formulae for O Level Chemistry

mole concept and stoichiometry formula

In this post, you will find a summary of all the mole concept and stoichiometry formulae you’ll need for your O Level Chemistry exams.

1. Converting number (of particles e.g. ions, atoms, molecules ,etc) to number of moles

number of particles = Avogadro’s Constant x number of moles

where Avogadro’s Constant = 6.02 x 1023

2. Converting mass to moles

moles = mass / molar mass

3. Converting volume of gas to moles

moles = volume of gas / molar volume

where molar volume = 24 dm3 at room temperature and pressure (r.t.p)

4. Converting concentration of solution to moles

moles = concentration (in mol/dm3) x volume (dm3)

5. Converting between different units of concentration g/dm3 to mol/dm3

concentration (g/dm3) = concentration (mol/dm3) x molar mass

6. Finding mass from concentration (in g/dm3)

mass (g) = concentration (g/dm3) x volume (dm3)

7. Stoichiometry Rules

The number (or coefficient) in front of each compound or element in a balanced equation represent the mole ratio required for the reaction. If there is no number in front of the element or compound, then it is 1.

Let’s use the equation below as an example:

2HCl + Ba(OH)2 –> BaCl2 + 2H2O

Based on the equation above, it tells us that the stoichiometry ratio of HCl to Ba(OH)2 in the reaction is 2:1. This means that 2 moles of HCl will react with 1 mole of Ba(OH)2 . If 0.3 moles of HCl is used, then 0.15 mole of Ba(OH)2 is needed for the reaction.

Key concept: Chemical reaction gives us the mole ratio of the reactants and products.

Want to learn more about mole concept and stoichiometry?

Want a course that will teach you mole concept and stoichiometry in an easy manner? Check out our course on mole concept and stoichiometry here.

We also have courses on other topics. All these are on-demand courses where students can watch them anytime, anywhere and learn at their own pace.

1. Foundation Topics:

In this course, students will learn the chapters on atomic structure, chemical bonding, elements, molecules and compounds, and also the fundamentals of chemistry – writing equations, and chemical formulae. Check out this course here.

2. Acids, bases and salts, Qualitative Analysis, Metals, Periodic Table, and Ammonia

In this course, students will learn acids, bases and salts, qualitative analysis, metals, periodic table and ammonia. I also share a way of remembering the metals in the reactivity series in this course. You can get this on-demand course here.

3. Mole concept and stochiometry

Questions on mole concept and stoichiometry can be combined with any other chapter. In this course, I will go through with you step- by-step all the concepts you need to know for mole concept and stoichiometry. You can get this on-demand course here.

4. Rate of reaction (reaction kinetics) and heat of reaction (enthalpy change of reaction)

These topics involve applying concepts learnt to scenario-based questions. In our on-demand course on the rate of reaction and heat of reaction, we go through the concepts and how to apply them to questions. You can get this on-demand course here.

5. Redox reactions, electrochemistry and electric cell

Learn redox reactions, and electrolysis and electric cell n this on-demand course here. Most schools cover electrolysis last, so if you want to learn ahead of your school, check out our course here.

6. Organic Chemistry

In O Level Chemistry, students are expected to know the properties, and reactions of alkanes, alkenes, alcohols, carboxylic acids, esters and polymers (addition and condensation polymers). We talk about them in detail in our on-demand course on O Level Organic Chemistry. You can get this on-demand course here.