Dimensional Analysis

Steps to Converting:
1. Identify what units you want to end up with
2. Find the conversion factor
3. Place units in appropriate places
4. Cancel units

Examples:
HOW MANY MILES ARE EQUAL TO 120KM?
-1.6 Km = 1 Mi
120 km x 1 mi     = 75 mi
              1.6 km

HOW MANY SECONDS ARE IN 1.4 HRS?
-1.4h x 60 min x 60s     = 5040s
              1hr       1min

Nicole H

Scientific Notation

Scientific notation is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation. Scientific notation has a number of useful properties and is commonly used in calculators, and by scientists, mathematicians, doctors, and engineers.
In scientific notation all numbers are written like this:

When are Digits Significant?

Non-zero digits are always significant. Thus, 22 has two significant digits, and 22.3 has three significant digits.

With zeroes, the situation is more complicated:

1. Zeroes placed before other digits are not significant; 0.046 has two significant digits.
2. Zeroes placed between other digits are always significant; 4009 kg has four significant digits.
3. Zeroes placed after other digits but behind a decimal point are significant; 7.90 has three significant digits.
4. Zeroes at the end of a number are significant only if they are behind a decimal point as in (c). Otherwise, it is impossible to tell if they are significant. For example, in the number 8200, it is not clear if the zeroes are significant or not. The number of significant digits in 8200 is at least two, but could be three or four. To avoid uncertainty, use scientific notation to place significant zeroes behind a decimal point:

8.200 ´ 10³ has four significant digits
8.20 ´ 10³ has three significant digits
8.2 ´ 10³ has two significant digits


Janine R

Classification of Matter

Divide Matter in 2 types:

1. Homogeneous: consist of only one visible component.
     ex. distilled water, oxygen, graphite
2. Hetergeneous: contains more than one visible component.
    ex. chocloate chip cookies, granite

                                                                            MATTER
                                       HOMOGENEOUS                                    HETEROGENEOUS
                   PURE SUBSTANCE       HOMOGENEOUS MIX               MECHANICAL MIXTURE
                        Element                                    Solution
                      Compound

Pure Substances
    Element: Substance cannot be broken into simpler substances by chemical reaction
                                         EX. oxygen, Iron, Magnesium
Compound: Substances made up of 2 or more elements and can be changed into elements by   chemical reactions
                                         EX. water, sugar

Mixtures
- many mixtures are easy to identify (chocolate chip cookies) BUT others are easily confused as pure substances.
Heterogeneous mixtures- different parts are clearly visible (granite, sand)
Homogeneous mixtures- different parts are not visible (salt, water, air)

Seperating Mixtures
- there are many methods to seperate mixtures, depending on the type of mixtures
           -by hand
           -filtration
           -distillation                                           Physical Changes
           -crystallization
           -chromatography

Nicole H

Chemical and Physical Changes

Chemical Changes

• a chemical change produces a new substance 
• the change cannot be undone
• the old matter is no longer present
• the original matter cannot be recovered

Rust forming on a nail

Physical Changes

• a physical change does not produce a new substance
• changes in state or phase such as melting, freezing, condensation and sublimation are physical changes
• you can return the substance back into its original state and vice versa

Ice melting can be turned back to ice

How to tell the difference ?
A chemical change makes a substance that wasn't there before. There may be clues that a chemical reaction took place, such as light, heat, colour change, gas production, odor, or sound. The starting and ending materials of a physical change are the same, even though they may look different.


Janine R.

Chemical and Word Equations

Today in Chemistry we learned how to form a chemical equation, going from word form -----> chemical form


For Example: 
      
        A solution of barium phosphate is mixed with aqueous sodium sulphate to yield solid barium sulphate and aqueous sodium phosphate.

*Notice the bolded words such as aqueous and solid. Those are the phases that those certain chemicals are in.

       Ba3(PO4)2 (aq) + Na2 SO4(aq) --->  Ba SO4 (s) + Na3 PO4 (aq)
*This is what the word equation should look like turning into a chemical equation 


       Ba3(PO4)2 (aq) +3Na2 SO4(aq) --->3Ba SO4 (s) +2Na3 PO4 (aq)
*This is what you would call a balanced chemical equation. It's so that on both sides of the equation (the arrow), there are a balanced number chemicals on each side. Now on both sides there are:

3 Bariums
3 Sulphates
2 Phosphates
6 Sodidums

*IF YOU STILL DON'T HOW I GOT THAT ANSWER PLEASE REFER TO THE FOLLOWING LINKS! THANK YOU FOR READING!  :)


http://www.youtube.com/watch?v=8KH3laR2iR4
http://www.standnes.no/chemix/examples/chemical-word-equations.htm

Sofia 

Lab Safety

Here are 10 rules for keeping safe while performing in the lab:

1. Wait for instructions before starting your lab
2. Long hair must be tied back at all times
3. Always wear safety equipment
4. Keep lab clean
5. No running in the lab
6. No fooling around in the lab
7. If a substance spills, alert Mr. Doktor immediately
8. Waft chemicals towards you, do not smell directly
9. Don't consume the substances
10. No food or drinks in the lab

Lab Safety Rap:
http://www.youtube.com/watch?v=yclOrqEv7kw

Nicole H

Welcome to our Chem 11 blog ... enjoy :)