Unit and Dimensional Analysis

4 steps how to convert units

1. Identify Solution
2.Find Conversion Factors
3. Place units in the right order and place
4. Cancel out the units


ex:
You want to convert 35 € to Canadian currency

To convert distance over time:
You want to change kilometers per hour to meters per second

It is crucial to learn how to convert units correctly in science, for more examples, click here
- Paul

Significant Digits & Scientific Notation

Significant Digits

The certain digits and the estimated digit of a measurement are together
Not all digits are significant
-All numbers other than zero are significant
-Place saving zeros aren't significant (decimals)
∟0.005= 1 S.D. ∟0.0050= 2 S.D.
When multiplying and dividing:
-round your answer to the lowest number of S.D in the initial numbers

When adding and subtracting:
-round to the lowest decimal place from the original numbers

Scientific Notation

When writing in scientific notation, numbers split into 2 parts:
-Number btwn. 1→10
-Power of ten
∟1000 = 10 x 10 x 10 = 10^3

-Paulo Santillan

Measurement and Error

SI Unit Prefixes, Multiples, and Symbols:

SI Base Units:

Base unit: A fundamental unit that is defined arbitrarily and not by combinations of other units. The base units of the SI system are the meter, kilogram, second, ampere, kelvin, mole, and candela.

Derived Units:

Derived Unit: combinations of base units used to measure area, volume, force, pressure, energy, power, voltage, frequency, and electric current.

Error
- Error is a fundamental part of science
- There are usually 3 reasons for error
- Physical errors in the measuring device
- "sloppy" measuring
- Changing factors

- 2 ways to calculate Error
- Absolute Error
- Formula : Absolute Error = Measured Value - Accepted Value
- Percent Error
- Formula :

- JanCarlo Paysan

Chemistry Units Joke

Q: What is the world's most smallest animal?
A: A "nano"-mole

-Paulo Santillan :D

Classification of Chemicals

Understanding matter begins w/ how we name it. We can divide matter into 2 types:
-Homogeneous: Consists of only one visible compound
-ex: distilled water, oxygen, graphite
-Heterogeneous: Contains more than one visible component
-ex: chocolate chip cookie, granite

Pure Substances

There are 2 types of Pure Substances:
-Elements: Substances that cannot be broken down into simpler substances by chemical reactions
-ex: oxygen, iron, magnesium
-Compounds: Substances that are made up of 2/more elements and can be changed into elements (or other compounds) by chemical reactions
-water(H2O), sugar(C12H22O11)

H2O + energy → (H2) + (O2)
∟ compounds split apart(by adding energy)

Telling the Difference

To identify an element or compound, the difference is only "visible" on the atomic level
One method is to connect the substance to an electric current.
-(Electrolysis) can split the compound apart into its constituent elements

Solution

A solution is a homogeneous mixture of 2/more substances
-Usually involve liquids (not always, like fog & steel)
The component present in greater amount is the solvent
-Water is most common solvent
-The symbol (aq) is used when something is dissolved
The component present in smaller amount is the solute

Mixtures

Mixtures can be easily identified, or can be confused as pure substances
-Heterogeneous mixtures, different parts clearly visible (granite, sand fog)
-Homogeneous mixtures, different parts aren't visible (salt water, air, brass)

Separating Mixtures

Many methods to separate mixtures, depending on type:
-By hand
-Filtration*
-Distillation*
-Crystallization
-Chromatography

^All physical changes
*Heterogeneous mixtures only

-Paulo Santillan

Physical and Chemical Change pt. 2

Today we examined the chemical reaction when lead nitrate and pottasium iodide was mixed together to form a yellow dye. We observed little crystal like balls accumulate resulting from the mix.

-Paul

Physical & Chemical Changes

Matter can undergo many changes
3 Categories
- Physical Changes
- Chemical Changes
- Nuclear Changes

Physical Changes
- Involves changing shape or state of matter
   - ex. crushing, tearing, ect....
- No new substances are formed
   - ex. boiling water, cutting wood, smashing cars, etc..

Phase Changets
- Changing from a solid to a gas can often be confused as a chemical change
   - chemicals remain the same
During the melting process chemicals usually follow this path

Chemical Change
- New substances are form
-Properties of the matter change
   -conductivity, acidity, colour, etc..
   -ex. iron rusting, burning wood, digesting food

Changes in Physical State
- Solid to Gas = Sublimation
- Solid to Liquid = Melting
- Liquid to Solid = Solidification / Freezing
- Liquid to Gas = Evaporation
- Gas to Liquid = Condensation
- Gas to Solid = Deposition / Sublimation

- JanCarlo Paysan

Blancing and Word Equations

*Phase symbols are subscripts that indicate the phase of the chemical.
ex. Al(s), H2O(l), H2(g), AgNO3(aq)

• (s) -----> Solid

• (l) ------> Liquid

• (g)-----> Gas

• (aq)----> Aqueous 

*in chem 11 a solution means something is dissolved in water therefore it is aqueous

*Diatomic Molecules

• H2   Hydrogen                                 *Polyatomic Molecules*
• O2   Oxygen                                           - P4 Phosphorus
• F2    Fluorine                                          - S8 Sulphur
• Br2  Bromine
• I2      Iodine
• N2    Nitrogen
• Cl2   Chlorine

Example of a Word Equation to a Balanced Equation

Word Equation : "a solution of barium phosphate is mixed with aqueous sodium sulphate to yield solid barium sulphate and aqueous sodium phosphate"


Balanced Equation: Ba3(PO4)2(aq) + 3Na2SO4(aq) ---> 3BaSO4(s) + 2Na3PO4(aq)

-JanCarlo Paysan

Safety Rules in a Lab

1) Work "only" under teacher supervision
2) Follow your Teacher's directions
3) Read all instructions and procedures
4) Notify your Teacher of any problems
5) Know how to use the Safety Equipment and materials in the Laboratory
6)Wear approved Safety Goggles and Lab coat
7)Wear proper shoes (no open toes)
8) Tie your hair back if you have long hair
9) Don't leave any unnecessary things out in the open, place them under a table (ex: bags)

10)Avoid making any awkward transfers with the chemicals used

11)"If it's Hot, Let it Cool"

12)Carry chemicals with extreme caution

13) No fooling around! (especially during experiments)

14)Dispose of chemical wastes properly

15) Make sure all equipment used during a lab is safe and "usable"
16) Throw away any broken glass
17) If on fire or any chemicals get on you, make sure you know how to use the shower head/ eye wash
18) Read chemical labels on glass
19)Don't taste anything
20) Food, drinks, and gum are prohibited
21) Do not look directly at test tubes
22) Don't directly smell chemicals, waft a small scent only
23) Clean up Afterward

-Paulo Santillan