Chapter 1, Problem 1.18E

Classify each of the following as (1) a physical property, (2) a physical change, (3) a chemical property, or (4) a chemical change. a. the process of burning a piece of newspaper b. the fact that metallic copper reacts with chlorine gas c. the process of melting ice d. the fact that metallic gold is a solid at room temperature

Which of the following are compounds, and which are elements? aNa2S bBr2 cPotassium hydroxide dFluorine eCompound or element fCompound or element

Decide whether each of the following is a physical property or a chemical property of the substance. a Salt substitute, potassium chloride, dissolves in water. b Seashells, calcium carbonate, fizz when immersed in vinegar. c The gas hydrogen sulfide smells like rotten eggs. d Fine steel wool (Fe) can be burned in air. e Pure water freezes at 0C.

All of the following processes involve a separation of either a mixture into substances or a compound into elements. For each, decide whether a physical process or a chemical reaction is required. a Sodium metal is obtained from the substance sodium chloride. b Iron filings are separated from sand by using a magnet. c Sugar crystals are separated from a sugar syrup by evaporation of water. d Fine crystals of silver chloride are separated from a suspension of the crystals in water. e Copper is produced when zinc metal is placed in a solution of copper(II) sulfate, a compound.

Classify each of the following properties as physical or chemical. Explain your reasoning in each case. a. Mercury metal is a liquid at room temperature. b. Sodium metal reacts vigorously with water. c. Water freezes at 0C. d. Gold does not rust. e. Chlorophyll molecules are green in color.

Which of the following are chemical changes? Which are physical changes? a. the cutting of food b. interaction of food with saliva and digestive enzymes c. proteins being broken down into amino acids d. complex sugars being broken down into simple sugars e. making maple syrup by heating maple sap to remove water through evaporation f. DNA unwinding

Classify each of the following properties of the metal magnesium as a physical property or a chemical property. a. Solid at room temperature b. Ignites upon heating in air c. Hydrogen gas is produced when it is dissolved in acids d. Has a density of 1.738 g/cm3 at 20C

In the following description of the element bromine, identify which of the properties are chemical and which are physical. Bromine is one of the few elements that is a liquid at room temperature. It is an acrid-smelling substance that reacts readily with most metals. It evaporates easily, so most containers of bromine are filled with visible amounts of red fumes. Most bromine is obtained from sodium bromide, a compound found in salt beds.

In each case, identify the italicized property as a physical or chemical property. Give a reason for your choice. The normal color of the element bromine is red-orange. Iron is transformed into rust in the presence of air and water. Dynamite can explode. Aluminum metal, the shiny “foil” you use in the kitchen, melts at 660 °C.