Term 1 Reflections

What I learnt

A term in Chemistry

This term, we were taught chemistry. To me, Chemistry is just mixing chemicals together to create new ones. I have never bothered to think deeper than that. However, in this one term that Chemistry was taught, I have learned more about it than I have ever had in my life. I personally think it was very fruitful, and I really enjoy the practical lessons we spent in the laboratory, mixing chemicals together and observing chemical reactions.

So here are the things that I have learnt:
-  Basic Chemical Calculations
- Acids and Bases
- Salts
- Atomic Structure
- Chemical Bonding
- Elements, Compounds, and Mixtures

Chemical Calculations

In Chemical Calculations, we basically were taught how to write chemical equations. One important point is that the equation has to be balanced. Here is an easy step-by-step guide on how to write a chemical equation for metaldehyde(C8H16O4), which burns in excess oxygen, producing carbon dioxide and water:
1. Write down the chemical formulas of the reactants and products of the reaction
     (C8H16O4--->CO2+H2O)
2. Balance the number of carbon and hydrogen atoms on both sides
    (C8H16O4--->8CO2+8H2O)
3. Balance the number of oxygen atoms
    (C8H16O4+10O2--->8CO2+8H2O)

And there you have it!

Acids and Bases

Some important definitions:
Acids- substances that produced H+ ions when dissolved in water
Strength of an acid- extent to which the acid molecule dissociates when dissolved in water
Base- reacts with an acid to form a salt and water only
Alkali- a base that is soluble in water
Neutralization reaction- Reaction between an acid and a base to form a salt and water only
Concentration- how much a substance is dissolved in 1 dm^3 of the solution
Strength- how easily an acid or an alkali dissociates when dissolved in water
pH scale- set of numbers used to show whether a solution is acidic, neutral or alkaline

In acids, the H+ ions are responsible for the properties of the acid, mainly:
- a sour taste
- conducts electricity in aqueous solution
- turns blue litmus paper red
- turns Universal Indicator orange or red
- reacts with reactive metals to form hydrogen and salt
  (metal + acid ---> salt + hydrogen)
This means that acids only show their properties when dissolved in water. Acids are also covalent compounds.
Acids have also many uses, such as:
Sulfuric acid- manufacture of detergents and fertilisers
Hydrochloric acid- leather processing and cleaning metals
Ethanoic acid- Used as flavouring agent for sour taste and as a food preservative

Properties of alkalis
- bitter taste
- soapy feel
- turns red litmus paper blue
- turns Universal Indicator green or violet
- reacts with acids to form salt and water only
- produces OH- ions when dissolved in water
- gives off ammonia gas when heated with ammonium salts

Some uses of bases and alkalis:
- Ammonia solution is used in cleaning solutions and fertilisers
- Calcium oxide is used in neutralizing acidic soil
- Sodium hydroxide is used in making soaps and detergents

pH scale ranges from 0 to 14, with pH <7 being acidic and >7 being alkaline. pH =7 is neutral.

Oxides

There are 4 types of oxides:
- Acidic oxide
- Basic oxide
- Amphoteric oxide
- Neutral Oxide

Here is an easy flow chart that can help you understand oxides better:

Term Test

I did very badly for the term test. I failed it, by a narrow margin. However, a fail will be a fail, and it was expected, as I could not really understand parts of it. Now, I understand the topics taught better, and the above 2 are the 2 subtopics that I think I am weaker in, compared to the others. I was extremely disappointed, as many science-related jobs require a good foundation in chemistry.