Answers to Chapter 2 Study Questions
1.† a)† An element is a fundamental substance that cannot be broken down into simpler substances by chemical means.† It is composed of atoms.
††††† b)† A compound is a pure substance made of at least two elements in a fixed ratio.
††††† c)† A pure substance can be an element or a compound.† It has a constant composition.
2.† a)† air = mixture, solution††††††††††††††††† b)† titanium = pure, element
††††† c)† oak = mixture††††††††††††††††††††††††††† d)† baking soda = pure, compound
††††† e)† oxygen =† pure, element f)† 7-Up = mixture, solution
††††† g)† wine = mixture, solution h)† carbon monoxide = pure, compound
3.† a)† element†††††††††††††† b)† compound†††††††††††††† c)† element††††††††††††††††††† d)† mixture
††††† a)† and b)† contain molecules.
4.† solid:† particles not moving and close; liquid:† particles moving and close; gas:† particles moving and far apart; aqueous (dissolved in water):† particles moving and far.
5.† chemical:† Chlorine reacts with sodium to form NaCl.† You could also list the formula of any ionic compound chlorine forms, such as MgCl2, CaCl2, etc.
††††† physical:† Chlorine is a pale green gas at room temperature.† Itís a nonmetal made up of diatomic molecules.
6. Chemical reactions are frequently accompanied by:
††††† a)† mass changes and/or bubbles which show that a gas is involved in the reaction.
††††† b)† heat changes;† heat is evolved in exothermic reactions;† heat is used up in endothermic reactions.† Exothermic reactions also often result in the production of light and sound.
††††† c)† color changes which often signify a change in chemical composition.
††††† d)† the formation of a precipitate (formation of a solid from mixing solutions) which represents the formation of an insoluble substance from soluble substances.
7.† a)† chemical b)† physical†††††††††††††††††† c)† physical†††††††††††††††††† d)† chemical
††††† e)† chemical††††††††††† f)† chemical†††††††††††††††††† g)† physical
8.† a)† Qualitative:† This page is colorful.† This page contains questions.
††††† b)† Quantitative:† This page is 8.5 in x 11 in.† The page contains 9 questions.
††††† Theory:† The questions on this page will be useful in studying for the test.
9.†† a)† beaker†††††††††††††† b)† Erlenmeyer flask††††††††††††††††† c)† graduated cylinder†††††††††††††† d)† pipet