Classification & Properties of Matter Answers
1.1 (a) gas (b) solid (c) liquid (d) gas
1.3 (a) heterogeneous mixture (b) homogeneous mixture (If there are undissolved particles, such as sand or decaying plants, the mixture is heterogeneous.) (c) pure substance (d) homogeneous mixture
1.5 Pure water is a pure substance, while a solution of salt in water is a mixture. We should be able to separate the components of the mixture by a physical process such as evaporation. Take a small quantity of the liquid and allow it to evaporate. If the liquid is salt water, there will be a solid white residue (salt). If the liquid is water, there will be no residue.
1.7 (a) C (b) Cd (c) Cr (d) Zn (e) I (f) S (g) O (h) Ne
1.9 (a) hydrogen (b) magnesium (c) lead (d) silicon (e) fluorine (f) tin (g) copper (h) calcium
1.11 A(s) --> B(s) + C(g)
When carbon (s) is burned in excess oxygen the two elements combine to form a gaseous compound, carbon dioxide. Cleary substance C is this compound.
Since C is produced when A is heated in the absence of oxygen (from air), both the carbon and oxygen in C must have been present in A orginally. A is, therefore, a compound composed of two or mroe elements chemically combined. Without more information on the chemical or physical properties of B, we cannot determine absolutely whether it is an element or a compound. However, few if any elements exists as white solids, so B is probably also a compound.
1.13 Physical properties: silvery white (color); lustrous; melting point = 649 C; boiling point = 1105 C; density at 20 C = 1.738 g/cm3; pounded into sheets (malleable); drawn into wires (ductile); good conductor. Chemical properties: burns in air to give intense white light; reacts with Cl2 to produce brittle white solid.
1.15 (a) chemical (b) physical (c) physical (d) chemical (e) chemical