February 2025

Oxidation of iron/Rusting

By |2025-02-12T09:44:16+02:00February 12th, 2025|Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Oxidation of iron/Rusting

  • Iron combines with oxygen to form rust
  • The oxidation process of iron is known as rusting
  • Rust is a reddish-brown crust that forms on iron
  • It is iron oxide
  • \text{iron+oxygen}\rightarrow\text{iron oxide}
  • Most iron objects such as nails, paper clips, wires and iron coins rust when they are exposed to the […]
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Experiment: Demonstrate the effect of surface area on the rate of a reaction

By |2025-02-12T09:14:05+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

 ZIMSEC O Level Combined Science Notes: Experiment: Demonstrate the effect of surface area on the rate of a reaction

Materials: magnesium ribbon, magnesium powder, marble chips (another form of calcium carbonate), powdered calcium carbonate, 250cm3 beakers, dilute hydrochloric acid, spatula, splint

Method a

  1. Into two beakers pour an equal volume of dilute hydrochloric acid about 20cm3
  2. Add a small spatula load […]
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Extraction of copper from oxides

By |2025-02-12T09:29:40+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Extraction of copper from oxides

  • In addition to sulphides
  • Copper ore can also be in the form of oxides
  • For example Cuprite
  • Unlike withe sulphides the oxygen in copper oxides cannot be driven off by roasting
  • Copper can be yielded by using the reduction process
  • Sodium carbonate is used in the process
  • It […]
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Uses of sulphuric acid

By |2025-02-12T09:43:37+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Uses of sulphuric acid

  • Most of the sulphuric acid produced at Zimphos is used to
  • make fertilizers (mostly superphoshate)
  •  Some of the sulphiric acid is used to  manufacture aluminum sulphate
  • Which in turn is used as a flocculent in water purification processes
  • Bauxite from Mutare is dissolved into sulphuric acid
  • The word […]
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Experiment: Demonstrating that carbon dioxide extinguishes a burning flame

By |2025-02-12T09:10:46+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

Carbon dioxide extinguishes flames Carbon dioxide extinguishes flames ZIMSEC O Level Combined Science Notes: Experiment: Demonstrating that carbon dioxide extinguishes a burning flame

Aim: to show that carbon dioxide extinguishes a flame

Materials:  3 different sized candles, vinegar, baking soda, beaker or plastic bottle, shallow dish

Method

  1. Place the 3 pieces of candle in a […]
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Experiment: Current and Voltage

By |2025-02-12T09:24:45+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: Experiment: Current and Voltage 

Aim: To show how current changes with voltage and to find the resistance of a resistor

Materials: Three/Four 1.5V battery cells, ammeter, lamp,resistor, switch, leads with crocodile clips

Method

 

Current and Voltage Current and Voltage

  1. Set up the series using one cell as shown in the […]
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The Ampere-Hour

By |2025-02-12T09:41:23+02:00February 12th, 2025|Notes, O Level Science Notes, Ordinary Level Notes|

ZIMSEC O Level Combined Science Notes: The Ampere-Hour

  • It is used to measure the current capacity of cells and batteries
  • is the amount of energy charge in a battery/cell that will allow one ampere of current to flow for one hour
  • It is thus a unit of measuring a cell/battery’s charge
  • For example if a battery is rated as […]
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