Conservation of matter

we had a short class today so we didnt get in as much as usual but hey we still learned a lot and even got around to blowing stuff up!

we learned about all the ways matter can be divided up in respect to mixtures and substances.

understanding matter begins with how we name it. we can divide matter into two types:

• HOMOGENEOUS: consists of one visible component. i.e. distilled water, oxygen or graphite
• HETEROGENEOUS:contains more than one visible component. i.e. chocolate chip cookies, granite
  

(sorry for the home-made-ness, but i couldn't find it on the web and didnt know other wise :P)

this chart we were shown in class shows us how matter can be catergorized with regards to their homogeneous or heterogeneous state

PURE SUBSTANCES

we learned there are two types of pure substnaces:

• ELEMENTS: substances that cannot be broken down into simpler substances by chenical reactions. i.e. oxygen, iron, magnesium
  
• COMPOUNDS: substnaces that are made up of two or more elements and can be changed into elements or other compounds by chenical reactions i.e. water, sugar

telling the difference...

it is often very difficult to tell the difference between elements and compounds. the differences are only visible on the atomic level. but there are ways to find out without looking at the atomic level. one way is through ELECTROLYSIS. this method is to connect the substance to an electric current. this method will split the compound into the elements it is made of, but if the substance is a pure element, no change will occur.

well this is pretty much all we learned today... oh right and i forgot to show you what we blew up!

as seen in this video, we blew up a balloon filled with hydrogen today in class. it was a great way to end the class!

Properties of Matter

Today we began unit 2 of chemistry, and actually began learning about the subject.

we learned that matter:
- is anything that has mass and occupies space
- can exist in many different states, but the most common are
- solid, liquid and gas
- plasma (in stars, can be aqueous or amorphos)

solids: has definite shape and volume

liquids: can change shape but has definite volume

gases: can change shape and volume

aqueous: something dissolved in water
e.g. NaCl(s) ----> NaCl(aq)



We also learned that matter can undergo many changes, and nearly all of them can be classified as physical, chemical or nuclear

***a note about phase changes ***
- changing from solid to gas can often be confused as a chemical change
- the chemicals remain the same


in a physical change:
-no new substances are formed (like boiling water, cutting wood, and smashing cars)
- involves changing the shape or state of matter (crushing, tearing, etc)

in a chemical change:
- new substances are formed
- properties of matter change (conductivity, acidity, colour, etc)
eg. iron rusting, burning water, digesting

here is a video of physical changes and chemical changes:


conservation of matter:
- in physical and chemical changes matter is NEVER created or destroyed. ever.
- this is called conservation of matter

here's a diagram to help with the idea of conservation of matter:




Thats all for now!

Sodium Chloride

Today, we did our first lab of the year! We explored the following problem:

What is the maximum amount of Sodium Chloride (Table Salt) you can dissolve in 200mL of distilled water?

We measured salt on a scale, then added it bit by bit to different amounts of distilled water with a scapula. We got the following results:

Trial	Volume of Water (mL)	Mass of Salt (g)
1	15	0.65
2	25	0.84
3	40	1.44
4	50	1.17

We also learned that we must expect that errors are going to be made during an experiment. For example, one time when the salt was being transported from the scale to the beaker, some dropped onto the counter. This would have resulted in a different mass of the salt that dissolved in the water, since we subtracted the new amount from the original amount on the scale.


We then created a graph to determine how much salt can dissolve in 200mL of water by graphing the data points and drawing a line of best fit.

above: salt dissolving into water

above: a look at salt dissolving, scientifically

Graphing!

today we learned all the things we needed to remember during the year for when we make a graph. appearently we will be doing it a lot so THIS IS IMPORTANT!

5 BASIC THINGS WE NEED

1. title- short and descrptive works best here. titles such as "time verses distance" or "speed of car verses time it takes" would be accepted as titles
2. labeled axis- full names of the data being respresented... AND DONT FORGET THE UNITS!!!
3. scale- we should be using about 70 percent of the space given for the graph, dont bunch it up in the corner. and dont use those squiggily things to make your graph longer, cuz its messes up your line. if your data starts at something higher than zero, just start there!
4. correct data plot- make sure you are accurate and precise with your data plotting. even the smallest mistake can cause things to be off.
5. line of best fit- use either a straight line of a SMOOTH curve. DONT JUST CONNECT THE DOTS!

linear graphs use the slope=rise/run to find the slope.

dont use the points you plotted for your slope calculation. instead, use the line of best fit. occasionally, there may have been an error in some of the gathered data, so the line of best fit will even it out so you can make a more accurate calculation

remember your line of best fit doesn't HAVE to start at zero.

there are different types of linear graphs

• direct relationship- the graph starts at zero and has a constant slope
• y=mx+b- this graph has a y-intercept, meaning it does not start at zero, making it a different type of linear graph

thats pretty much all thats new from today! problems? questions? queries? HAHA :P

here is an activty you can do to practice the placement of your line of best fit here (scroll down to the box that says "line of best fit")

Measurement, Accuracy, and Significant Digits

Today we learnt about the metric system and that it has 7 fundamental units.

1. Meter (m)- Length
2. Kilogram (kg)- Mass
3. Seconds (s)- Time

4. Amphere (A)- Current

5. Mole (mol)- Amount

6. Kelvin (k)- Temperature

7. Candela (cd)- Luminosity Intensity

We also learnt about Prefixes used with the "Le systeme International d'Unites" = Si System.

Apple has used the word "Nano" to exaggerate the size of the ipod nano.

We also took notes on significant zero

1) If there is a decimal after the zero it is significant.

IE. 1020. 302980.

2) You must round to the least percise number

IE. 4212-3.54= 3.8812 S.D.s= 3.88

3) When you multiply and divide, round to the number with the fewest S.D.s

IE. 2.5x5.55= 13.875 S.D.s= 14

Near the end of class we watched two youtube videos. One of a bridge collapsing and the other a swing fail. http://www.youtube.com/watch?v=3q27dzRgHLo