Lesson 1 answers:
Chapter 1
15) A homogeneous mixture has the same composition in all its parts and at all
scales down to the molecular scale.
(a) Homogeneous: the ions are dispersed evenly throughout the solution.
(b) Heterogeneous: the composition inside the ice cubes is different to the
composition in the tea.
(c) Heterogeneous: the composition of the noodles and the soup is different.
(d) (For ‘smooth’ mud) homogeneous down to the scale of the microcrystals of
clay suspended in water. Heterogeneous from the scale of the microcrystals to
the molecular scale. [Note: you would not be expected to give such a precise
answer in an exam].
(e) homogeneous: gasoline is a mixture of liquids that has the same composition
at all scales
(f) carbon dioxide is a pure substance, not a mixture.
(g) heterogeneous. The composition of ice cream and the chocolate chips is
different.
18) (a) gasoline is a mixture of hydrocarbon liquids. (b) tap water is a mixture of
water and various solutes (c) calcium carbonate is a compound: it has a definite
chemical formula. (d) ink is a mixture of solvent and dye. (e) vegetable soup is a
mixture of various ingredients in water (f) aluminium foil is made from the
element aluminium.
23) (a) a chemical process. (b) physical. (c) chemical. (d) chemical (e) physical
Chapter 2
14. (a) Mg2+ monatomic cation. (b) SO32– polyatomic anion. (c) Cu1+ monatomic
cation. (d) NH4+ polyatomic cation (e) O2– monatomic anion.