January 2023
SeedCo trial fields are used for breeding seeds. Image credit Experiment: The heating curve of water
The heating curve of water. Image credit wordpress.com ZIMSEC O Level Combined Science Notes: Experiment: The heating curve of water
Materials: beaker, crushed ice, thermoter, burner, clock/watch with a stop watch function
Method
- Half fill a beaker with crushed ice
- Record the temperature of the ice
- Place […]
Properties of Nonmetals vs metals
Common metal objects. Image credit blogspot.com ZIMSEC O Level Combined Science Notes: Experiment: Properties of Metals and Non-Metals
- Elements can be divided into two groups:
- Metals and Non-metals
- Examples of metals are: copper, zinc, iron, gold, silver, chrome, lead and tin
- Almost all metals have certain properties that makes them […]
Differences between reduction and oxidation
ZIMSEC O Level Combined Science Notes: Differences between reduction and oxidation
- There are differences between oxidation and reduction
- The table below shows the differences between oxidation and reduction:
- Often reduction and oxidation occur in conjunction
- That is at the same time and during the same reaction
- For example:
- \text{ammonia+oxygen}\rightarrow\text{water+nitrogen dioxide}
- Nitrogen gains oxygen and losses hydrogen […]
Experiment: The effects of a catalyst on the rate of a reaction
Copper (II) can be used as a catalyst. Image credit chemistry-reference.com ZIMSEC O Level Combined Science Notes: Experiment: The effects of a catalyst on the rate of a reaction
Aim: To investigate the effects of a catalyst on a reaction using […]
Galvinasing iron
Corrugated iron sheets are galvanised. Image credit alibaba.com ZIMSEC O Level Combined Science Notes: Galvinasing iron
- Galvanising is one of the methods used to prevent iron from rusting
- Iron and steel can be coated with zinc
- Zinc is a fairly more reactive metal
[…]
The production of Nitric acid
ZIMSEC O Level Combined Science Notes: The production of Nitric acid
- Some of the ammonia produced using the Haber process is used in the production of nitric acid
- The first stage in the process of making nitric acid is the oxidation of ammonia
- To form nitric acid
- \text{ammonia + oxygen} \rightarrow\text{nitric oxide+ water+heat}
- This an exothermic reaction
[…]
The Petrol engine
Four Stroke Petrol Engine. Image credit petrolheadkenya.com ZIMSEC O Level Combined Science Notes: The Petrol engine
- Four strokes are involved in the operation of most petrol engines
- They are thus known as four-stroke engines
- The first stroke is known as the inlet stroke
- During the […]
Experiment: Determining the resistance of resistors in parallel and in series
Resistors in series ZIMSEC O Level Combined Science Notes: Experiment: Determining the resistance of resistors in parallel and in series
Aim: To determine the combined resistance of resistors in series and in parallel
Materials: 4 cells, 2 bulbs/2 resistors, switch, ammeter, voltmeter, leads with crocodile clips
Method ![Resistors in [...]
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Experiment: Generating electricity
A dynamo. Image credit wikihow.com ZIMSEC O Level Combined Science Notes: Experiment: Generating electricity
Aim: To generate electric current
Materials: dynamo, lamp bulb, copper wires, crank or a set of pulleys and weights to turn dynamo, rubber band
Method
- Set up the apparatus with the dynamo on a table, the rubber […]