Chapter 1 Marking

Chapter 1 Marking
Notes: Feel free to comment on or contest my marking. My marking scheme is below.
You did a really great job! Congratulations!

TOTAL MARK: 57 / 65 = 87.7%

Chapter Questions
1.3 - 2/2
1.4 - +2 You didn't have to do this question!
1.7 - 0/4 You should have done this one instead!
1.11 - 4/4
1.15 - 4/4
1.17 - 4/4 Question c - the case could be made that if one phase is present it is not automatically a homogenous substance eg oil and water could not be called homogenous yet they are both liquid.
1.19 - 3/4 Question d - three phases would be present since it is carbonated (gas), and ice (solid).
1.21 - 3/4 Question d - why would this make it an element?
1.25 - 2/4 Question a - what does this mean "not all compounds are pure"? If they are mixed up with other compounds than they are not pure, but if elements are mixed up with other elements, they are not pure either. Question b: Hahaha, but I don't think this is what they were asking... Question c: can two elements not form a heterogeneous mixture (eg boron, a solid, and mercury, a liquid)?
1.33 - 4/4 Very good!
Chapter Questions Total: 28 / 34

Assignment Questions
3. 6/6 Sorry about the Mica, mate... Yeah the structure of table sugar is really crazy - we had to memorize it for biochem this year.
4. 2/2
5. 3/3 Silicone, hahaha!
6. 3/3 Interesting thoughts!
7. 3/3
8. 2/2
9. 2/2 Good work - this one was tricky!
10. 3/3 Next time, try to find something that hasn't already been discussed in the book.
11. 3/4 Question b - dissolving salt is a physical change as you are not changing its chemical composition
12. 1/3 Although you are right about changing the form of a physical object being difficult to undo, in chemistry, chemical changes are the less reversible because with physical changes, the structure of the molecule has not changed, but with chemical changes it has, and this can be difficult to undo, and usually requires some input of energy. See water: changing it from H2 and O2 releases huge amounts of energy, but requires that same input of energy to change it back into H2 and O2. Good answer though!
Assignment Questions Total: 28 / 31

Bonus: +1 Yaay!



Marking Scheme:
3. (6) What are the names of the elements that make up:
a. Ethanol - carbon, hydrogen, oxygen
b. Table sugar - carbon, hydrogen, oxygen
c. Table salt - sodium, chlorine
d. Mica - sodium, potassium, calcium, aluminum, magnesium, iron, silicon
e. Bismuth - bismuth
f. Codeine - carbon, hydrogen, oxygen, nitrogen

4. (2) What is the difference between a pure substance and an element?
An element consists of only one type of atom, where as a pure substance, which may be either an element or a compound, is not contaminated with any other element or compound of a different composition.

5. (3) What are the two most abundant elements on earth? What common substance do these make?
Silicon and oxygen. They make rocks.

6. (3) What do you notice about the two most common elements in the universe in regards to the periodic table? Make a guess as to why this is.
Hydrogen and helium are the first two elements on the periodic table, and also possessing the least complicated structure. Perhaps in the early universe, these were the most easy to form and thus most common atoms formed.

7. (3) What is the difference between a molecule and an atom? When you breathe, is your body trying to obtain a molecule or an atom?
A molecule is made up of two or more atoms. Your body is trying to obtain a molecule of oxygen, which is made up of two oxygen atoms (O2). In fact, atoms of oxygen are very reactive and therefore are not found in nature for any length of time as an oxygen atom.

8. (2) How many elements make up a molecule of aspirin? How many atoms?
Three elements make up a molecule of aspirin - carbon, oxygen, and hydrogen. Twenty one atoms make up a molecule of aspirin.

9. (2) How many elements make up a molecule of Ca(NO3)2? How many atoms?
Three elements make up this molecule - Calcium, nitrogen, and oxygen. Nine atoms make up this molecule.

10. (3) Find another substance that is commonly thought of as toxic (ie bad) and find a good use for it (see "good vs bad properties for a chemical substance" on page 4).
Who can tell what this guy will think up?

11. (4) What kind of change is it?
a. boiling acetic acid to produce acetic acid vapour - physical
b. dissolving salt into water - physical
c. burning a batch of chocolate chip cookies - chemical
d. making acetic acid from baking soda and vinegar - chemical

12. (3) What can you say about the reversibility of physical changes versus chemical changes?
Chemical changes are the less reversible because with physical changes, the structure of the molecule has not changed, but with chemical changes it has, and this can be difficult to undo, and usually requires some input of energy. See water: changing it from H2 and O2 releases huge amounts of energy, but requires that same input of energy to change it back into H2 and O2.

34 marks for chapter questions
31 marks for assignment questions
65 marks total


Bonus: (1)To what classic video game character is the Latin word (and hence the symbol on the periodic table) for lead related? Hint: it has to do with his/her profession.
Lead was often used in pipes in the Roman world. Lead was known as plumbum, therefore people who fixed these lead pipes became known as plumbers. Mario and Luigi are video game characters who are plumbers