Chem 121 Exam 1

Question 1

what are atoms?

Answer 1

the smallest particle of pure substances

Question 2

what are molecules?

Answer 2

the smallest particle 2+ atoms together which forms substances

Question 3

what is the scientific method?

Answer 3

observation/question
research topic area
hypothesis
test with experiment
analyze data
report conclusions

Question 4

what is a scientific theory?

Answer 4

all the experimental evidence for a proposed mechanism; explains why or how it happens

Question 5

what is a scientific law?

Answer 5

same thing, but it has calculations; describes what happens

Question 6

what are the three states of matter?

Answer 6

solid, liquid, and gas

Question 7

what is decanting?

Answer 7

it is for heterogeneous mixtures
slow pouring of a liquid off the top (water off of wet sand)

Question 8

what is distillation?

Answer 8

it is for homogeneous mixtures
boiling off of the more volatile liquid and then condensing it

Question 9

what is filtration?

Answer 9

for heterogeneous mixtures
insoluble solid in liquid (pour it through filter paper in a funnel)

Question 10

what are physical changes?

Answer 10

change in state of matter or appearance only

Question 11

what are chemical changes?

Answer 11

change in atoms or molecules

Question 12

what is kinetic energy?

Answer 12

energy in MOTION (and thermal energy that is lost in transfer)

Question 13

what is potential energy?

Answer 13

energy that is in storage?

Question 14

what is the first law of thermodynamics?

Answer 14

energy is not created nor is it destroyed, always transfer among kinetic, potential, and thermal transfer