Thursday, September 30, 2010

Physical, or Chemical Change?

We performed our first lab experiment and wrote our first lab report today. The purpose of the lab was to reinforce (or rather review) what we've learned about physical & chemical change. We witnessed examples of both changes during the lab.

Recall 

Physical Change: the substance's state of matter changes; change is reversible
                              ie. the substance can go back to its original form
                             -NO new substance is formed

Chemical Change:a new substance IS formed
                              -change is irreversible, or exceptionally hard
                              -can be identified by a new odour, new colour, heat production, 
                               or gas formation
                           

As some extra practice, identify whether the following are examples of physical or chemical change.

1. A towel absorbing all the water in a sink
2. Inflating a volleyball
3. Lighting a match
4. Chewing food
5. Digesting food
6. A rusting nail of a building's exterior
7. Clouds forming in the sky
8. Crushing ice in a blender
9. Explosion of fireworks
10. A rotting apple

You have now mastered the identification of changes!
Give yourself a pat on the back. (:
That's it for this post! Until next time~



Written by: Jialynn

Monday, September 27, 2010

Matter, Physical and Chemical Change (Isabelle)

Isabelle Cheng
September 27, 2010
Block 2-2 Chemistry 11 
Ms.Chen
Matter
  • anything that has mass, volume, and takes up space
  • has length, width, and height
  • can change from one state to another
  • is conserved
  • includes atoms and other particles
  • includes physical and chemical change
  • example: everything around you

Matter
(Lines are for separation of categories)
                           
ELEMENTS:
  • can move from one phase to another
  • pure substance that can’t be broken down into 
  • smaller substances 
  • simplest kind of matter
  • also called chemical element
  • building blocks of matter
  • example: elements on the periodic table

COMPOUNDS:
  • combination of two or more elements joined together
  • made up of two or more types of elements
  • can’t be broken down into two or more simpler substances 
  • elements form compound to make it stable
  • pure substances
  • example: water, carbon dioxide
____________________________________________
MIXTURES:
  • substance created by combining two or more different materials
  • combining two or more different substances so there is no chemical reaction 
  • can be separated and go back to original forms
  • mostly natural substances
  • can be separated into pure compounds or elements
  • example: salad, salt water


________________________________________________

HOMOGENEOUS MIXTURES:
  • same uniform appearance and composition
  • referred to solutions
  • only composed of one phase 
  • is not very visible
  • example: salt water, soapy water

HETEROGENEOUS MIXTURES:
  • mixture of two or more different substances in form of solution
  • composed of mixed phases
  • consists of visible different substances or phases
  • no definite composition
  • inconsistent
  • can be seen by just looking at it
  • can be seperated
  • three phases are solid, liquid, and gas
  • example: sandy water, sugar and salt mixed in a bowl

States of Matter

  • SOLID: - rigid
  • particles are touching with very little space between them
  • has definite volume and shape
  • mostly hard material because particles and closely packed together
  • can hold their shape
  • Can be made of many different materials
  • Example: Rocks, crystals






  • LIQUID: - partially rigid
  • - particles are touching slightly with space between them
  • hard to compress
  • has definite volume
  • particles are able to move around
  • Example: Water, blood




  • GAS: - not rigid
  • major spaces between particles 
  • not compacted 
  • no definite volume or shape
  • really spread apart and bounce around constantly
  • can fill an entire container not depending on size or shape
  • can hold huge amounts of energy and particles

Physical and Chemical Change
PHYSICAL CHANGE:
  • Uniform
  • Change that affects size, shape, odor, volume, mass, weight, or color of a substance
  • Change the state of matter
  • Can happen by increasing or decreasing of temperature
  • No new substance is formed 
  • Matter changing in appearance without forming new substances
  • Reversible
  • Easily reversed to get original material back 
  • Example: Melting ice can freeze back into ice again

CHEMICAL CHANGE:
  • Not uniform
  • New substances are formed
  • Changes - color, odor, solubility, phase
  • One or more new substances are made/created
  • New substance/material is different from the original
  • Change that makes a new kind of matter with different properties
  • Not reversible
  • Example: Burned wood can not return back to the original piece of wood, raw eggs that became cooked can not be uncooked

video

Websites:

Sunday, September 26, 2010

Scientific Notation And Square & Cubic Rates (by Bev)

SCIENTIFIC NOTATION


Scientific notation is a way to express very small or very large numbers.  The number in standard form (or decimal notation), must be
  • between 1 & 9.9999999...
  • multiplied by 10 to the appropriate power
ex. a) 25,100,000,000 = 2.51 x 10^10

b) 0.0000000302 = 3.02 x 10^-8

c) 3.25 x 10^8 = 325,000,000

d) 7.86 x 10^-5 = 0.0000786

SQUARE & CUBIC UNIT RATES

If 1m = 100cm
   1m^2 = 10,000cm^2              (100cm x 100cm)
   1m^3 = 1,000,000cm^3         (100cm x 100cm x100cm)

ex. a) 8.1m^3 --> km^3

Think first!

10^3m = 1km
therefore...
10^9m^3 = 1km^3

8.1m^3 x km^3/10^9m^3 = 8.1 x 10^-9

b) 4.3dm^2 --> Gm^2

dm  --> m --> Gm

10^2 dm^2 = 1m^2           (10 x 10)
10^18m^2 = 1Gm^2         (10^9 x 10^9)
4.3dm^2 x m^2 / 10^2dm^2 x Gm^2 / 10^18m^2

chem Sept. 23rd, 2010 by Mandy Xiao

The general form of a unit conversion calculation,
 UNKNOWN AMOUNT = INITIAL AMOUNT X CONVERSION FACTOR

Memorize the SI Prefixes and Conversion Factors Table!!!
10^12
10^9
10^6
10^3
10^2
10^1
10^-1
10^-2
10^-3
10^-6
10^-9
10^-12
tera
giga
mega
kilo
hecto
deka
deci
centi
milli
micro
nano
pico
T
G

M

k

h
da

d

c

m
µ

n

p



Base Units In The International System (SI)
QUANTITY
WRITTEN UNIT
UNIT SYMBOL
Length
Metre
M
Mass
Gram
g
Time
Second
S
Amount of substance
Mole
mol


Some Important Equivalences

1mL = 1 cm^3
1cm^3 = 10^3 L
1t = 10^3 kg

Exercises
1)      How many micrometres are there in 5 cm?
(µm) – (m) – (cm)
# of µm – 5cm x 10^-2 m / 1cm x 1 µm / 10^-6 m = 5x 10^4 µm

2)      Express 8 kg in milligrams.
1kg = 10^3g
1mg = 10^-3g
(kg) –(g) – (mg)
# of mg = 8kg x 10^3 g/ 1kg x 1mg/10^-3g = 8x 10^6 mg

now, a little science cartoon :)
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