Solutions to p4 to p8
1. a. no
2. a. Research the topic.
b. You would probably waste time by not being familiar with the topic.
3. a. In science, hypotheses are tested experimentally.
b. The most reliable references are journals because they reveal the data and reasoning behind the scientist's conclusions. Journals may still contain errors, but such sources are easier to expose. The work has also been scrutinized by editors who have submitted the paper to other scientists. They check to see if they could get similar results in the lab.
4. a. heterogeneous because the fat floats to the top. For milk to be homogenized, the fat has to be broken up into smaller globules so that they get suspended within the rest of the milk.
c. all solutions are homogeneous
d. all elements are homogeneous
e. all elements are homogeneous
f. all compounds are homogeneous
g. all compounds are homogeneous
i. all compounds are homogeneous
5. a. solution
6. a. chemical
7. a. chemical
8. a. b, e, k, m
b. - burns with a highly unusual blue and stinking flame
- melts at 119 oC
9. a. oxidizes very easily; decomposed by water or alcohol
b. highly corrosive; reacts with organics; burns powdered glass; even some inerts react with it
c. offers a protective coating; speeds up certain reactions
e. forms sulfides; bleaches dry fruit; combines with oxygen...
10. a. zinc Zinc is a bluish-white, shiny metal. It is a brittle at ordinary temperatures but malleable at 100 oC to 150 oC, and it melts at 419 oC. It is a fair conductor of electricity
b. oxygen Solid and liquid oxygen are pale blue, and O2 turns into a liquid at -183 oC. The gas is colourless, tasteless.
11. a. physical
12. A. hydrogen
C. carbon dioxide
13. a. density
b. sweet-smelling an gets people to giggle
14. measure their densities: they will be different
or measure their boiling points
15. evaporate the liquid from each solution; dry the white powder. The flammable one will be sugar.
16. physical = same chemical properties
17. chemical = a colour change accompanied by an increase in mass suggests that a gas became chemically bonded to the substance