줌달의 일반화학 해답 다운로드
줌달의 일반화학 해답
줌달의 일반화학
해답
1047810_ans_A41-A71.qxd
9/8/08
4:21 PM
Page
A41
Answers to Selected Exercises
The answers listed here are from the
Complete Solutions Guide, in which rounding is carried out at each intermediate
step in a calculation in order to show the correct number of signicant gures for
that step. Therefore, an answer given here may differ in the last digit from the
result obtained by carrying extra digits throughout the entire calculation and
rounding at the end (the procedure you should follow).
Chapter 1
19. A
law summarizes what happens, e.g., law of conservation of mass in a chemical
reaction or the ideal gas law, PV nRT. A theory (model) is an attempt to explain
why something happens. Dalton’s atomic theory explains why mass is conserved in
a chemical reaction. The kinetic molecular theory explains why pressure and
volume are inversely related at constant temperature and moles of gas. 21. The
fundamental steps are (1) making observations; (2) formulating hypotheses; (3)
performing experiments to test the hypotheses. The key to the scientic method is
performing experiments to test hypotheses. If after the test of time, the
hypotheses seem to account satisfactorily for some aspect of natural behavior,
then the set of tested hypotheses turns into a theory (model). However,
scientists continue to perform experiments to rene or replace existing theories.
23. A qualitative observation expresses what makes something what it is; it does
not involve a number; e.g., the air we breathe is a mixture of gases, ice is
less dense than water, rotten milk stinks. The SI units are mass in grams,
length in meters, and volume in the derived units of m3. The assumed uncertainty
in a number is 1 in the last signicant gure of the number. The precision of an
instrument is related to the number of signicant gures associated with an
experimental reading on that instrument. Different instruments for measuring
mass, length, or volume have varying degrees of precision. Some
instrumen
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