Chapter 1, Problem 1.21E

Classify each of the following as a physical or chemical change, and give at least one observation, fact, or reason to support your answer. a. A stick is broken into two pieces. b. A candle burns. c. Rock salt is crushed by a hammer. d. Tree leaves change color in autumn.

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 decomposing hydrogen peroxide b. the fact that a block of ice can be chipped into smaller pieces c. the process of evaporating a liquid d. the fact that water freezes at 32F

Classify each of the following changes as physical or chemical: a. the crushing of salt b. the rusting of iron c. the burning of natural gas in a stove d. the vaporization of gasoline

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 elements, and which are compounds? a NaOH; b BaCl2; c He; d Ag; e Fe2O3.

Which of the following properties depicts a chemical process? a.Helium is combined with neon b.Iron forms rust c.Water causes soil erosion d.Ice melts

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

Distinguish precisely and in scientific terms the differences among items in the following groups. a Macroscopic matter, microscopic matter, particulate matter b Physical change, physical property, chemical change, chemical property c Gases, liquids, solids d Element, compound e Atom, molecule f Pure substance, mixture g Homogeneous matter, heterogeneous matter h Reactant, product i Exothermic change, endothermic change j Potential energy, Kinetic energy

Classify the following as homogenous or heterogeneous: aThe contents of the beaker on the left in the photograph bThe contents of the beaker on the right in the photograph cReal lemonade made by squeezing lemons and adding sugar and water dBeach sand