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Bases and alkalis for O Level Chemistry

bases and alkalis as tested in O level chemistry

In this post, let’s look at bases and alkalis as tested in O Level Chemistry.

What are bases?

Bases are metallic oxides or hydroxides that react with acids to form salt and water only.

Bases and alkalis

Alkalis are a subset of bases. Only bases that are soluble in water are called alkalis.

Since bases react with acids to form salt and water, so do alkalis. Like how we define acids in terms of Arrhenius acids, we can also do so for alkalis. Arrhenius bases are substances that dissociates in water to give hydroxide ions (OH).

Common properties of alkalis

Alkalis are bitter in taste, have a soapy feel, are corrosive and turns red litmus paper blue.

Reactions of alkalis

1. Alkalis (and also bases) react with acids to form salt and water only This reaction is called neutralisation.

Word equation: acid + alkali –> salt + water

2. Alkalis react with ammonium salt to form salt, water and ammonia gas upon heating.

Word equation: alkali + ammonium salt –> ammonia gas + water + salt

More on acids, bases and salts

Want a simplified course that will teach you the basics of acids, bases and salts and more? Check out our course on acids, bases and salts 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.