Simple differences between mixtures and compounds
2 marks · EasyA sealed container holds 36 g of water and 12 g of oxygen gas. Calculate the total mass of compound present and the total mass of element present in the container. Identify which substance is a compound and which is an element.
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Water is a compound (36 g present); oxygen is an element (12 g present).
Also accept: 36 g water (compound); 12 g oxygen (element).; There is 36 g of a compound (water) and 12 g of an element (oxygen).
Common mistakes: Stating both are elements or both are compounds.; Mixing up the classification (e.g. water as an element).
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Marking points
M1 · 1 mark · Correctly identifies water as a compound and oxygen as an element.
A1 · 1 mark · Correctly states or calculates the total mass of the compound (36 g) and the element (12 g). (follow-through)
Worked solution
Water is a compound because it consists of two elements chemically combined (hydrogen and oxygen). Oxygen gas is an element because it consists only of oxygen atoms.
Total mass of compound: 36 g (water).
Total mass of element: 12 g (oxygen).