Unit # 3 - MATTER AND ENERGY Identify which of the following as a pure substance or a mixture. (a) salt, NaCl pure substance mixture (b) air pure substance mixture (c) brass. pure substance mixture (d) H2O pure substance mixture (e) beer pure substance mixture Identify which of the following pure substances are elements, and which are compounds (a) mercury element compound (b) rust, iron oxide element compound (c) aluminum element compound (d) tungsten element compound (e) diamond element compound Identify which of the following mixtures are homogeneous or heterogeneous. (a) beef vegetable soup homogeneous mixture heterogeneous mixture (b) fog homogeneous mixture heterogeneous mixture (c) water and gasoline homogeneous mixture heterogeneous mixture (d) sugar dissolved in water homogeneous mixture heterogeneous mixture (e) 14 carat gold homogeneous mixture heterogeneous mixture Determine whether each of the following properties is physical or chemical. (a) A block of styrofoam floats on water. physical property chemical property (b) Sugar becomes caramel when heated above its melting point. physical property chemical property (c) Iron dissolves in hydrochloric acid and hydrogen gas evolves. physical property chemical property (d) Lithium metal has a shiny surface. After exposure to air, it becomes dull. physical property chemical property (e) An iron nail is attracted to a magnet. physical property chemical property Determine whether each of the following is either a chemical change or a physical change. (a) pure water from seawater physical change chemical change (b)Electricity is passed through water to produce hydrogen and oxygen gases. physical change chemical change (c) A white T-shirt is dyed red. physical change chemical change (d) A wet mop dries in the sun. physical change chemical change (e) Making ice cube in the freezer. physical change chemical change