Activity What happens to magnesium when it is burned in air?
Method 1. Take a piece of magnesium ribbon (10 cm approx.) 2. Carefully sand down the surface with some fine-grade sandpaper until it is shiny. Scrunch up the magnesium ribbon and place it in a crucible.
3. Record the initial mass. 4. Heat over a Bunsen burner with a strong blue flame. 5. When the magnesium ignites, remove the Bunsen and hold the crucible lid over the crucible. Try to prevent most of the white smoke escaping from the crucible but do not close the lid completely or else the magnesium will stop burning. 6. Allow to cool and record the mass.
Questions What effect has burning had on the mass?
Activity What happens when different substances are mixed?
A. Sand and water Half-fill a measuring cylinder with sand (up to the 50 cm3 cylinder with 50 cm3
the total volume. Explain your observations.
B. Alcohol and water Carefully measure out 50 cm3
of water and 50 cm3 of alcohol. Predict what the combined
volume should be. Pour the alcohol into the water and measure the total volume. Does your observation support the idea that all materials, including liquids, are composed of tiny particles that are too small to see?
Nature of Science
In this chapter we learned about units for measuring mass. Units such as grams and kilograms are part of the SI system of units. The SI system is used in most countries of the world.
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Question: How does having an internationally agreed system of measurement help scientists to communicate their ideas?
mark). Half-fill another measuring of water. Pour the water into the cylinder containing the sand. Note Fig. 19 Magnesium burned in air.
