Phys Science 416/430 Name_______________________

Pretest 1.1

1. Classify as either an observation or an interpretation

a. Jane realized that her brother had been through her schoolbag because it was filled with his fingerprints.

b. In 27 seconds, the gray liquid in the thermometer rose from 20.1 to 23.5^oC.

c. Upon heating the solid, bubbles of nitrogen appeared on its surface.

d. When a glowing splint was placed into the tube, a flame quickly appeared.

2. You believe that people born under the "Virgo" sign have no major similarities between them, and that in general, astrology is more hocus-pocus than a science. How do you test your hypothesis? Be specific.

3. A student wants to know what compounds are found in bananas. She goes directly to the lab, runs all sorts of experiments, and weeks later she has learned very little. What is wrong with her approach based on what you know about the scientific method?

4. What are the two types of homogeneous substances?

5. Explain the differences between a compound and an element.

* How do you tell them apart from their formulas?

* Use the word atom to differentiate between them.

* Which will lose weight when it becomes the other?

6. A student puts a lit match in a tube of gas and hears a pop. What should she look for to make sure that a chemical reaction has indeed taken place?

7. Classify as a solution, compound or element.

a. boron (B ) b. water c. a homogeneous mixture of KBr and water

d. a mixture of air and perfume hours after the bottle was opened

e. Na₃PO₄

8. TRUE? OR FALSE?

a. CO₂ has three types of atoms.

b. Compounds and elements are pure substances.

c. A boiling point is NOT a characteristic property.

d. If these two atoms move apart then a chemical reaction will occur.

e. When chocolate melts it undergoes a physical change.

f. A characteristic property of oxygen is that it makes limewater cloudy.

g. Iron, zinc, oxygen, water and brine all have different densities. Thus, density is a characteristic property.

h. Laser , heat and radio waves are an examples of matter.

9. Which are CHEMICAL properties ?

a. A nail can be bent out of shape._____________________

b. A fallen leaf can decompose._____________________

c. Iron can rust in the presence of water and air._____________________

d. At room temperature iodine produces iodine gas_____________________

e. The freezing point of water is 0o C_____________________

f. Tar from cigarettes destroys lung cilia_____________________

10. Someone gives you four gases to identify. In no particular order they are

hydrogen carbon dioxide oxygen air

Here are the results of a student's experiments:

UNKNOWN A It makes a glowing splint stay lit for 8 seconds;

no reaction with limewater.

UNKNOWN B It makes a glowing splint turn black immediately.

UNKNOWN C It burns violently.

UNKNOWN D You ran out of time; no tests were done, but you were advised not to hold the test tube upside down.

Identify the four unknowns.

11. You are given three beakers containing different substances. You compile your observations in the table below :

Observations

	State	Colour	Volume (ml	Cobalt chloride paper test	Blue litmus paper test	Electrical Conductivity (does light go on?)
Beaker 1	liquid	Light yellow	25 ml	tip turns pink	Blue	Yes
Beaker 2	liquid	Clear	51 ml	All pink	Blue	A bit
Beaker 3	liquid	Clear	82 ml	Stays blue	blue	No
Beaker 4	liquid	Light blue	99 ml	Middle turns pink	red	Yes

a. In which of the beaker(s) was water present?

b. Which of the beaker(s) contained an acid?

12. If a compound becomes an element, how will the mass of the two substances compare?

13. List four other ways of identifying a chemical change.