Question

postlaboratory assignment

1. state whether the following properties are more typical of a metal or a nonmetal element.

(a) silver solid
(c) ductile solid
(e) high melting point
(b) yellow solid
(d) colorless gas
(f) poor conductor

1. classify each of the following as an example of an element, compound, homogeneous mixture, or heterogeneous mixture.

(a) copper, cu
(c) copper oxide, cuo
(b) copper alloy
(d) copper ore

1. classify the following as a physical property (phys) or a chemical property (chem).

(a) copper metal has a red - orange metallic luster.
(b) copper metal has a density of 8.94 g/cm³.
(c) copper metal and chlorine gas produce cucl₂.
(d) copper metal has a melting point of 1084 °c.
(e) copper metal conducts electricity.
(f) copper metal and acid give no reaction.

1. classify the following as a physical change (phys) or a chemical change (chem).

(a) silver tarnishes when exposed to air.
(b) baking soda fizzes when added to vinegar.
(c) alcohol dissolves when added to water.
(d) white phosphorus glows when exposed to air.
(e) soap and tap water form an insoluble \bathtub ring.\
(f) water evaporates from a lake.

Explanation:

Step1: Recall metal and non - metal properties

Metals are typically good conductors, ductile, have high melting points, and are solids at room temperature (except mercury). Non - metals can be solids, liquids, or gases at room temperature, are often poor conductors, and may have lower melting points.
(a) Silver is a metal, so silver solid is typical of a metal.
(b) Yellow solid can be a non - metal (e.g., sulfur).
(c) Ductile solid is typical of a metal.
(d) Colorless gas is typical of a non - metal (e.g., oxygen).
(e) High melting point is typical of a metal.
(f) Poor conductor is typical of a non - metal.

Step2: Recall element, compound, and mixture definitions

An element is a pure substance made of only one type of atom. A compound is a pure substance made of two or more different types of atoms chemically combined. A homogeneous mixture has a uniform composition throughout, and a heterogeneous mixture has a non - uniform composition.
(a) Copper, Cu is an element.
(b) Copper alloy is a homogeneous mixture (a solid - solution of metals).
(c) Copper oxide, CuO is a compound.
(d) Copper ore is a heterogeneous mixture (contains copper compounds and other impurities).

Step3: Recall physical and chemical property definitions

A physical property can be observed or measured without changing the substance's chemical identity. A chemical property is observed when a substance undergoes a chemical change.
(a) Red - orange metallic luster is a physical property (phys).
(b) Density of 8.94 g/cm³ is a physical property (phys).
(c) Reaction with chlorine to produce CuCl₂ is a chemical property (chem).
(d) Melting point of 1084 °C is a physical property (phys).
(e) Conducting electricity is a physical property (phys).
(f) No reaction with acid is a chemical property (chem).

Step4: Recall physical and chemical change definitions

A physical change does not change the substance's chemical composition. A chemical change results in a new substance with a different chemical composition.
(a) Silver tarnishing is a chemical change (chem) as silver reacts with sulfur compounds in air to form silver sulfide.
(b) Baking soda fizzing in vinegar is a chemical change (chem) as carbon dioxide gas is produced.
(c) Alcohol dissolving in water is a physical change (phys) as no new substance is formed.
(d) White phosphorus glowing in air is a chemical change (chem) as it reacts with oxygen.
(e) Soap and tap water forming an insoluble "bathtub ring" is a chemical change (chem) due to the reaction between soap and calcium/magnesium ions in hard water.
(f) Water evaporating from a lake is a physical change (phys) as it is a change of state from liquid to gas without changing the chemical composition of water.

Answer:

1. (a) metal

(b) non - metal
(c) metal
(d) non - metal
(e) metal
(f) non - metal

1. (a) element

(b) homogeneous mixture
(c) compound
(d) heterogeneous mixture

1. (a) phys

(b) phys
(c) chem
(d) phys
(e) phys
(f) chem

1. (a) chem

(b) chem
(c) phys
(d) chem
(e) chem
(f) phys