Chemical and Physical Change Lab

Today, we had our first lab of the year! We only worked with mild chemicals, so there wasn't much of a safety issue. For our experiment, we were given 4 unknown chemicals.

We would take one chemical and mix it with another, to see what kind of change occurs, as well as to determine whether it's a physical or a chemical change.

As you all know very well, no new substances are created in a physical change. It is a change that you can always reverse.

However, a chemical change does create new substances, and you can't change it back.

In this lab, we used a glass square and combined the solutions together with a medicine dropper. So if the unknown chemicals are A, B, C, and D, we were to observe the mixtures of AB, AC, AD, BC, BD, and CD. Some of them had no change, but others changed coloured, so it was easy to see the change.

Medicine dropper for mixing the chemicals


The handy-dandy safety goggles


And some test tubes


And now we have to do a lab report...................................... :(

What is Matter?

Just as the question asks: What is Matter?

Have you ever thought of what your pencil was made of? or your TV? 

It's all made of matter, because they are things that have a mass and a volume (in other words, they take up space)

There are two types of matter: Pure substances and Mixtures

Pure substances only have a single set of properties as well as only one kind of particle. i.e. it cannot be separated.

On the other hand, mixtures have more than 1 set of properties, and they are physically combined.


Pure substances can be divided into two more subcategories: Elements and Compounds.


Elements are substances made of atoms that cannot be separated into simpler substances, whereas compounds are substances of molecules that are composed of two or more elements which are combined chemically.  


Examples of elements are the metals, non-metals, and metalloids found on the Periodic Table. Examples of compounds are ionic compounds and covalent compounds


Mixtures can also be divided into two subcategories: either homogeneous or heterogeneous.


Homogeneous mixtures are uniform throughout, meaning that there only appears to be one component to the mixture. An example of these mixtures is a solution, such as salt dissolving in water. You can't see the salt after it has dissolved into the water, because it has become salt water. 





Heterogeneous mixtures are the exact opposite of homogeneous mixtures. They are not uniform throughout, so more than 1 component of the mixture is visible. For example, water and oil don't mix, so you can see both the oil and the water.


Matter is neither created or destroyed; instead, it is only changed from one form to another, by a physical change or a chemical change.


In a physical change, no new substances are formed. The chemical composition does not change, and the whole process is reversible, so you can always change it back to what it originally was. For example, if an ice cube melts, you can always freeze it again to make it a solid again. 


However, in a chemical change, new substances are produced. This is an irreversible process. For instance, if you burn a piece of paper, you can't get that same piece of paper back. You can tell that it is a chemical change from signs such as a smell, increased heat, or if a solid such as precipitate has formed. 

As you may already know, there are 3 states of matter: solid, liquid, and gas. 
Solids are rigid, and cannot change shape easily. There is only a small change of volume when it is heated.
Liquids will take the shape of a container, and there are slight changes to the volume when it is heated.
Gases take the shape of a container, and there are drastic changes in volume when it is heated.

If you're into rap, here's a cool song for you to better understand the three states of matter :)

Review: Unit Conversions

During last day's class, we reinforced our knowledge in converting units. We further extended our skills as we did some review. As you all know, practice makes perfect!!

Converting units isn't hard, as long as you work at it, and understand the basic fundamentals. Converting units allows you to change different units of measurement for the same quantity.

For example: If you wanted 1L of milk, and you wanted to convert it to mL, then you can set up an equation and find out the result.

1L  x  10^3mL
          ______       = 1 x 10^3mL    
             1L

You have just converted 1L into mL. Here we can see that 1L = 10^3 mL, which is the same as 1000 mL.
* Because you wanted to find out how many mL is in one Litre, when setting up your equation, make sure that the L unit is able to cancel out.

1L  x  10^3mL
          ______       = 1 x 10^3mL    
             1L



Watching this video will help you with your understanding of converting units:
 

Doing more of these questions will help strengthen your understanding on how to convert units.You can go on these websites for practice.
http://chemistry.about.com/library/metricmetric.pdf
http://serc.carleton.edu/files/mathyouneed/metric_conversion_pp.pdf

Good luck on your conversions!

Scientific Notation: An Easy Way to Read Large or Small Numbers

Have you ever wondered how scientists deal with really large or really small numbers? They put it into a scientific notation format. This is done by expressing numbers using powers of 10.

Here's how to write your very own scientifically notated number:

Let's say you have a number like 16 000 000.

First place the decimal number after the first non-zero digit. Here, we would get 1.6

*The rule is that the number before the decimal must be between 1 and 10.*

Next, you would multiply the number, 1.6, to a power of 10, depending on how big the number is. In this case, we would have to multiply by 10^7.

So in the end, we get 1.6 X 10^7. That is now a scientifically notated number.

Here is a very good video that further explains scientific notation.





For even more help, here are some helpful links:

http://en.wikipedia.org/wiki/Scientific_notation 
http://staff.argyll.epsb.ca/jreed/math7/strand1/1103.htm


Quiz yourself here!
http://janus.astro.umd.edu/cgi-bin/astro/scinote.pl

Unitary Rates

How do we convert 1 m^2 into cm^2? It's easy to convert 1 m into 100 cm, but what if it was a square metre?

We know that 1 m = 100 cm

So then 1 m^2 = ? cm^2?

First, we realize that we are squaring the left side of the equation. In mathematics, we learn that when we do something to one side of an equation, we must do the same to the other side, so we would square 100 cm.

(100 cm)^2:

This will equal 10000 cm^2. So 1 m^2 = 10000 cm^2

If we want to convert 1 km^3 into m^3, first we have to realize that 1 km = 1000 m. If we cube the "km" side, then we also have to cube the "m" side, which means that 1 km^3 = (1000 m)^3 

The answer is 100 000 000 m^3.