September 30th

Today we did our very first experiment involving chemical and physical changes! How exciting! :)

But first of all, if you can recall from the last class, what separates a chemical change from a physical one?

A chemical change is a change in the chemical composition of a substance. It cannot be undone, and new substances are created. A physical change, on the other hand, is a change in the physical state of a substance. It's reversible and no new substances are formed.



Yum! A rotting apple is a chemical change, as the oxygen reacts with the apple to produce something new. A melting
ice cube is a physical change because it is reversible and nothing new is created.



Experiment 2C: Chemical and Physical Change

Materials:

• four of the smallest test tubes available
• a test tube rack
• four medicine droppers
• a glass square
• safety goggles
• four samples of unidentified substances, which each went into a different test tube

Procedure:

1. First, we put on our safety goggles (safety is first, after all!).
2. Next, we placed each test tube into a hole in the test tube rack, calling them A, B, C, and D.
3. Ms. Chen placed a different kind of substance in each test tube, filling them about a third of the way.
4. Next, we drew a grid (below) the size of the glass square on a white sheet of paper.
   

   	A	B	C	D
   A
   B
   C
   D

   
   
5. We placed the clear glass square on the grid, lining it up so that the cells matched the holes in the glass. This made it easier for us to see which outcome was which when we were combining the solutions.
6. 
   
   The fun part! Taking the medicine dropper, we combined the solutions as shown in the white cells of the grid: AB, AC, AD, BC, BD, and CD.
7. 
   
   We recorded our results on a separate sheet of paper, on a grid that looked exactly like the one above. If there were no changes to the mixture, we wrote that down as well.
8. 
   
   Afterwards, we cleaned up (thoroughly, of course), and wrote our write-up on the results of the experiment.

The results:

In all, but one of the mixtures, chemical changes occurred. These ranged from colour changes (one mixture turned bright blue, another one canary yellow, and a third combination was a faint green), to fizzling (small bubbles popped up in the mixture, to solidifying (one mixture hardened, turning a milky white colour).

We were able to complete our objective (recording some characteristics of chemical changes), by witnessing firsthand the results of chemical combinations! :)

Extras:

 

^ Here's a fun and lively drink you can offer to your friends the next time you have guests over!

...don't.

Homework:

• 
  
  Lab 2C write-ups are due Friday
• 
  
  Chapter 1 + 2 test is on October 21st

See you guys soon!

September 27th

Today we had our quiz on......

• Unit Conversions + Scientific Notation.
• SI Prefixes & Conversion Factors.
• *Also had a bonus question at the end that was associated with Norton*

Before we had our quiz we spent around 20 min. on starting our new subject...Matter!

Here are some facts about Matter:

• Matter is anything that has mass and takes up space (like us)...in other words, it has volume
• Matter is made up of two things: Pure Substances and Mixtures

Pure substances can't be physically broken down into simpler substances. They have one set of properties, and one kind of particle. They can either be elements, or compounds.

Mixtures contain more than one set of properties. They are either homogeneous, which means they only have one components to them, or heterogeneous, which means that they are made of several different components.

We also reviewed the differences between Physical Change and Chemical Change:



Don't waste paper...



1) Physical Change:

In a physical change, only the appearance of the object changes. No new products are formed. For example, if you crumple up a piece of paper, it will now look completely different, but it's properties are still that of the original piece of paper.

Remember:

In a physical change:

1. No new substance is formed.
2. Chemical composition does not change
3. Reversible (think of the boiling point and melting point)

2) Chemical Change:



This guy has just created a new substance from burnt
paper.



In a chemical change, the object might not only end up looking different, but will create new products out of the reaction as well. Some clues that a chemical change took place are the release of light, odor, or heat. If you take a new piece of paper and burn it, that's a chemical change, because you have added heat to the paper and created a new substance, which is no longer paper.

Remember:

In a chemical change:

1. New substances are produced.
2. It is irreversible (for example, you can't "unburn" something).

And lastly a few more properties of matter:

• It is neither created nor destroyed, only changed from one form to another
• There are three states of matter: Solid, Liquid, and Gas

Extras:

^ Here's a neat little song about Physical and Chemical changes...the next big hit?

Elements, Compounds, and Mixtures Quiz

^ Test your knowledge on elements, compounds, and mixtures with this little quiz!


For next class, we are going to be doing a lab which is called:

Experiment 2C: Chemical and Physical Change

HW:

• Bring lab textbook to next class for the lab, DON'T FORGET!!!!
• On pg.18, make a flow chart of the instructions/procedure otherwise you will not be able to complete the lab (and you have to sit and watch everyone else...)
• On the bottom of pg. 19, copy the chart on a separate white sheet of paper.
• Lastly, read the lab and instructions/procedures so you are prepared for next class.

Thank you and Good Night :)

September 23

     We started the class by marking the two homework worksheets:
"Even more UNITARY RATES" (white one) and "Review WS-scientific Notation" (brown one).
     It was basically a review of what we have been learning combined. There wasn't any new materials covered today.
     Afterwards, we had a practice quiz on Chapter 1-"Unit Conversions with Quantities" and marked it together. Examples of the questions are:

1. Convert 0.845 mol into millimoles.
    0.845mol  x 1000 = 845 millimoles.
2. Convert the speed of sound in air(1234km/hr) to cm/ms.
    1234km x 1/3600 x 1/1000 x 100000 = 34.3cm/ms

There was also an interesting bonus question:
A farmer need to wrap a gift of 2 horses where 3 horses = 5 cows, 1 cow = 5 hogs, 3 hogs = 5 goats, 1 goat = 9 chickens. How would the farmer pay for the 2 horses with chickens?

Answer = 250 chickens!

Lastly, for homework, make sure you are prepared for the Chapter 1 (unit conversion) quiz on Monday!!
Remember to MEMORIZE the SI prefixes and Conversion factors Table! (at least top 3 rows)
Practice Questions you can do:
1. a). 1mm -> km
    b) 56 L -> mL
    c) 45.2 dm -> cm
2. A dog barks 5 times per minutes. How many times will the dog bark in 7 minutes?
3. There are 40 weeks in a school year. Hwo many seconds are there in this time?
4. A human adult has on average 2 square feet of skin. There are about 75 mites per mm2 on your skin. Each mite eats 2 ug of dead skin per day. How many kg of skin gets eaten by mites per year? (note: 1foot = 30.48cm)

September 21, 2010

Review:

Today we marked Exercise B in our Unit Conversion Practice sheet. Unlike Exercise A, which mainly involved single-step procedures, Exercise B required two steps:

Step One: The transition first to the unit of measurement that equalled 10 to the power of 0 (or just 1). This would be either grams (g), meters (m), seconds (s), or liters (L). (I like to think of these as the “basic” measurements”.)
Step Two: The move from grams/meters/seconds/liters to the desired unit.

After we were finished with the worksheet, we moved on to a new lesson: scientific notation.

Scientific Notation

Scientific notation is an useful method of simplifying very big numbers or very small numbers. So when you get a number like "325,000,000,000,000,000,000", you can be saved the trouble of writing all those pesky zeros down by instead writing just "3.25 x 10²⁰".

Big Numbers

1. If it's a really big number, always move the decimal place up until only one digit is still to the left of that little dot.
example: 770000000 becomes 7.70000000
2. Next, count the number of places the decimal dot has moved (in the example above, it's 8). This number will be the little number to the top-right corner of the 10 (the exponent, in other words, geez).
example: 7.70000000 x 10⁸

Small Numbers

1. If it's a really small number, always move the decimal place down until only one digit is still to the right of that little dot. 
example 1: 0.00041 becomes 4.1
If there's only one non-zero number at the end, place the dot just to the left of it.
example 2: 0.0004 becomes 4.0
2. Next, count the number of places the decimal dot has moved and that number will, again, be your 10's exponent (in the example 1 above, it's -4...negative because you moved the decimal dot up to make the number bigger, and so to revert back to its original form, the exponent must be negative).
example: 4.1 x 10^-4

Scientific Notation on Your Calculator:

Really, really easy stuff. Say you get an equation like (2.2 x 10⁴)(9.7 x 10^-12)

1.      First, turn your calculator on (to do this, press the ON button…there you go).

2.      Next, input the first number (in this case, 2.2)

3.      Now here comes the magic. Press the EXP button on your calculator. Your screen should now say 2.2  00. (Yes, the spacing is deliberate).

4.      Now input the exponent (in this case, it’s 4). Your screen should now say 2.2  04.

5.      Press the = button to get 22000. Remember this number.

6.      Now do the same for the other one. Input 9.7, press EXP, and add -12. Press the = button. Your screen should say 9.7- 12.

7.      Multiply 9.7- 12 by 22000 to get 0.000000213, or 2.13 x 10⁷. Ta-da!

 Extras:

Scientific Notation Explained

^ Just in case that thorough and articulate explanation wasn't enough, here's a video for you.

Scientific Notation Quiz

...and a quiz (calculator optional).



Afterwards, we finished up with…

Even More Unitary Rates

This is quite similar to what we did in Exercises A and B. Except this time, instead of the “basic” measurements being 10 to the power of 0 (or 1), they could be to the power of 2, or 3.

For example, before today we would use 1m = 100cm for conversions. Now, we can use 1m² which doesn’t equal 100cm, but 10000cm² (think of it as 100cm x 100cm).

Likewise, 1m³ would mean 100cm x 100cm x 100cm, which is equal to 1000000 cm³ or just 10⁶ cm³.

Conversions can be done using the exact same procedures we used for previous questions. Just be wary of the exponents.

An example from our notes. Notice how 1 Gm² is equal to 10¹⁸m². Before, we worked with → 1 Gm is equal to 10⁹m.



Homework:

Review WS - Scientific Notation worksheet - all

Even more UNITARY RATES worksheet - front page only

Quiz on the 27th.