Matter and its Changes- Sept 28 Class

In Monday's lesson we learned the States of Matter, Changes in Matter, Physical Changes, Phase Changes, Chemical Changes, and the Conservation of Matter. Also, we got to watch a youtube video of mythbusters as an example to figure out the chemical and physical changes that occurred.


What is Matter?
-Anything that has mass and occupies space
-Matter can exist in many different states, the most common are:

• Solid, Liquid, Gas
  
• Plasma, Aqueous (dissolves in water), Amorphous
  
  

-Solids: holds one shape and has a definite volume (strong bonds)
-Liquids: can change shape, but has a definite volume (weak bonds)
-Gas: can change shape & volume (no bonds)
-Aqueous: something dissolved in water
-Plasma --> ionization


Changes in Matter
- Matter can undergo many changes
- Nearly all changes can be broken down into 3 categories:

• Physical Changes
  
• Chemical Changes
  
• Nuclear Changes
  

Physical Changes
- Involves changing shape or state of matter (crushing, tearing, etc.)
- No new substances are formed (Eg. Boiling water, cutting wood,
smashing cars)




Phase Changes
- Changing from a solid to a gas can often be confused as a chemical change
- Chemicals remain the same


Chemical Changes
- New substances are formed
- Properties of the matter change

• Conductivity, acidity, color, etc.
• Eg. Iron rusting, burning wood, digested food

Physical change of water into hydrogen peroxide


Conservation of Matter
- In Physical and Chemical Changes, matter is neither created nor destroyed.

This is the link of the video we watched of mythbusters:
http://www.youtube.com/watch?v=MWJU6sbf8Ng

Chapter 1 Review- September 21st Class

Today in Class we finished doing our NaCl labs and write-ups. We also had time to review for the upcoming chapter one test.

Below are some helpful study tools to study the various things in chapter one that we will be tested on.

Sodium Chloride Lab - Sept 17 Class

In the beginning of class, we reviewed Dimensional Analysis since we didn't get a chance to go over it thoroughly in the previous class. Here are some examples of unit conversions:


If you have trouble converting milligrams into kilograms, then you could always break it down into grams first. The 2 kilograms and the other 2 grams cancel each other out, leaving you with 120.000,000mg (120,000 x 1000).


This problem includes dealing with measurements and time as well. We must remember to incorporate both information. The Litres and the seconds each have another pair to cancel each other out, leaving you with 435 000mL/min (7.25 x 60 x 1000).


Once again we have broken down kg into g because it is easier to convert g into Mg. This problem also includes time that needs conversion as well. The kilograms, seconds, and grams all cancel out, and the end result is 626.4Mg/h (174 x 3600 x 1000/1,000,000).


After we did a little bit of review, we started our very first lab called Sodium Chloride.


















Purpose
To experiment the maximum amount of salt you can dissolve in 10mL, 20mL, 30mL, and 40mL.

Materials
- Sodium Chloride
- 150mL of Distilled Water
- 100mL graduate cylinder
- 50mL beaker
- 100mL beaker
- Weight paper
- Electronic Scale
- Lab coat
- Safety Glasses

Procedure
1. Gather all the materials an put them on the lab bench.
2. Measure 10mL of distilled water using the graduated cylinder. Transfer this water into a 50mL beaker.
3. Weigh 50 g of Sodium Chloride.
4. Add Sodium Chloride to the water until it stop dissolving and the first salt crystals begin appearing on the bottom of the beaker.
5. Measure the mass of salt remaining. Record the difference in salt as the amount added to the 10mL of water.
6. Repeat steps 2-5 for 20mL, 30mL, and 40mL of water.
7. Record all your data in the table below.
8. Create a graph of Mass of Salt vs Volume of Water.

Observations

The results can and may vary.





http://www.youtube.com/watch?v=Kxbc8nuv_0k

This video is similar to the lab we did today. The only differences were the scales, how they measured the ingredients, and they shook the salt and water together instead of stirring it with a glass rod.

Calculators - Sept 15 Class

- Your calculator has functions that you can use to do this easily

• EXP
• EE
• X10
• S.N.

- Do NOT use the '^' on your calculator. It does not recognize the order of operations in all cases

Expressing Error
- Error is a fundamental part of science
- There are usually 3 reasons for error:

Physical errors in the measuring device

'Sloppy' measuring

Changing ambient conditions

- Error is taken to be half the smallest division on your measuring device

Calculated Errors
- Two different parts of possibilities: Absolute Error and Percentage Error
- Absolute Error:

• measured value minus accepted valueabsolute error = measured - accepted
• positive number means you're over the accepted value
• negative number means you're under the accepted value

- Percentage Error:

• most common
• percent error = absolute error/accepted value
  

Example: You measured the weight of an orange to be 15N. The atual weight is 17.5 N. What i the percentage error? (14%)

Dimensional Analysis

- Want to know what 100km/h is in miles/hour?
- Just like converting between currencies, in Chemistry it is usually necessary to convert between units.. this process is called dimensional analysis

Steps
- There are 4 steps:

1. Find a unit equality
2. Find the conversion factors
3. Add a conversion factor
4. Cancel units

Example: How many miles are equal to 120 km?

Posted by Erin

Measurement & Chemistry - Sept 11 Class

In friday's lesson we learned the 7 Fundamental Units, Prefixes & SI units, and Significant Digits.

- Accurate measurements are essential in the scientific method.
- The SI system (System International) is the most common system in use today.
- France started the metric system about 300 years ago.

7 Fundamental Units (*need to know or most likely to use)

• Mass* (kg)
• Distance* (m)
• Time* (s)
  
• Temperature* (K)
  
• Amount* (mol) ----> 6.02 x 10^23
  
• Current (A)
  
• Luminosity (cd)

Prefixes & SI Units

Use the prefixes to convert the symbols!


Significant Digits
1. Digits 1-9 are always significant.
2. Zeros are significant if they are right of the decimal.

EX. 2.010-->ALL 4 digits are significant compared to 0.002-->ONLY the "2" is significant.