Dimensional Analysis: is the technique of converting between units! There are only 4 basic steps to solving a problem using Dimensional Analysis Steps:
Find the unit equality
Find the conversion factor
Apply conversion factor
Cancel units
Now FOLLOW these easy steps to solve the problems. Here are step-by-step examples :)
How many inches are in 250 centimeters?
1 in= 2.54cm
d= 250cm x 1 in
2.54cm
d= 98.4 in
How many dollars is E35.00?
1E=$1.4
35E x $ 1.4 =$49.00
1
What is 100 km/h in miles/hour?
100 km x 1mi = 62.5 mi/h
h 1.6km
If u still don't understand this concept... Here's a quick video that will show how to do Dimensional Analysis.. :)
Unit Equality is also very important... Unit equality is the starting point for solving the problem. A unit equality is an equation that shows how different units are related.
In our last Chem 11 class, we learnt about Significant Digits and Scientific Notation!
The concept of significant digits and scientific notation is pretty simple to grasp, so here are a few notes for you
A Significant Digit is a digit in a measurement that is certain, plus one digit that is an estimate
Here's an example, there are three significant digits in the number 34.5. Two of which are certain, 3 and 4; and one which is estimated, 5.
When trying to tell how many digits are significant, remember when a zero is not significant. place holder zeroes in a measurement are not significant
An example is 1040, how many significant digits are there? Well, to start off the 1 and the 0 are are exact and the 4 is an estimation. Therefore, there are only three significant digits. The final zero is a place holder zero and isn't significant.
When we add or subtract numbers, we determine the number of significant digits by depending on the number with the largest uncertianty
Here's an example, 951.0 + 1407 + 23.911 + 158.18 = 2540., the decimal place is there to show that the final zero is not a place holder, but significant.
When we multiply or divide two numbers, we determine the number of significant digits by choosing the smallest number in the equation.
An example is, 3.052 x 2.10 x 0.75 = 4.8, which means that there are two significant digits and we only use two digits because the smallest number of significant digits in the equation is 2.
Scientists have developed a shorter method of experssing large numbers, this method is called scientific notation, which is based on powers of the base number 10
The number 123, 000,000,000 is written as 1.23 x 10^11
Writing a number in scientific notation is easy!
Put the decimal after the first digit and drop the zeros. To find the exponent count the number of places from the decimal to the end of the number
So, in 123,000,000,000 there are 11 places after the decimal place which determines the exponent, which is 11.
That wasnt so hard, now was it?
Try out some examples to perfect your knowledge of Significant digits and Scientific Notation Scientific Notation
6.34 x 10^5 =
4.89 x 10^-6 = Significant Digits
0.0026701 =
19.0550 =
to end off the lesson, heres a mind boggling video on the relative size of things in the universe. (:
As a recap form the previous lesson "Mixtures" There are many methods to seperate mixtures, depending on the type of mixture.
- By hand
- Filtration <------ heterogeneous mixtures only
- Distillation
- Crystallization
- Chromatography
Here is an example of the process filtration ^
Now something new we learned last class was uncertainty in measurements. Here are some few notes:
Accuracy: Degree of closeness of measurements Precision: Repeated measurements that show the same results
The image of a dartboard is an excellent example of both Accuracy and Precision.
Measurements are uncertain for 2 reasons: Measuring instruments are never completely free of flaws & measuring always involves some estimation. We use a plus or minus symbol like this one ----> ±
to show uncertainty of a measurement.
There is also a metric system called International System of Units, abbreviated SI (after the French System International d'Unites) which had streamlined at an international conference in 1960. The SI is built upon a set of 7 metric units, which are called base units of the SI
But the base SI units are not always convenient to use. There is a convenient way of writing the measurement by using the metric prefix. Metric prefixes are attached to the base unit.
A very important note from the lesson was Percent Error.
Error as you all may know is an inescapable part of science. One may think that error is a BAD thing in an experiment but it is actually wrong!! In many ways Scientists need error in an experiment in order for the experiment to be succesful. Successful?!? How can this be you may ask well... Error actually helps scientists with experiments because when an experiment ends up not functioning properly, scientists can learn from their mistakes of the FAIL experiment and new measures can be taken up to improve the mistakes.
Yesterday in Chem11 we learned about the classifications of Matter...
Here are some notes
We can divide matter into two main types of Substances:
Homogeneous
- One type of substance that we can see (ex. Distilled Water, Milk, Oxygen, Graphite)
Heterogeneous
- Contains more than one visible component (ex. Sand, Blood, Granite, Chocolate chip cookie)
Below is a chart that helps describe how Matter is classified:
From the branch "Homogeneous Substances" comes two other branches.
The first is labeled 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 or more elements and can be changed into elements (or other compounds) by chemical reactions (ex. Sugar, Water).
* How do you tell the difference?
Often VERY difficult to tell the difference between Elements and Compounds (their differences are only 'visible' on the atomic level).
However you can use Electrolysis to help you.
Pretty cool right?! :)
2. The second branch is labeled Homogeneous Mixtures.
in Homogeneous Mixtures, the different parts are not visible.
a Solution is a homogeneous mixture of 2 or more substances.
Solutions usually involve liquids but don't necessarily have to (ex. Fog, Steel).
The component of a solution which is present in greater amount is the Solvent (Water = most common solvent).
On the other side of the diagram is the category "Heterogeneous Substances" which links the last branch.
The last branch we talked about was called Mechanical Mixtures. We didn't go into too much detail about it but it's basically this...
a mixture whose components can be separated by mechanical means.
This leads us to our last topic which is Separating Mixtures. There are many ways to do this but it depends on the type of mixture. For example, Filtration is used for Heterogeneous mixtures only. The other four listed in our notes are "by hand, distillation, crystallization, and chromatography. All of these are 'Physical Changes.'
Here's a video on some of the different ways you can separate mixtures:
For many of us Physical and Chemical Changes were just a review of what we learned from grade 8, 9 & 10...but for some of us who don't, Physical and Chemical Changes are easier than you may actually think!
Here are some key notes from Mr. Doktor that will give you ideas and insight on what Physical and Chemical Changes are all about:
Physical Change:
- Involves changing shape or a state of matter
Examples: Crushing, Tearing, etc..
-No new substances are formed
Examples: Cutting wood, Boiling water, etc...
Chemical Change:
- New substances are formed
- Properties of the matter changes
Now that you are a bit familiar with Chemical & Physical Changes, can you identify some of the things in this video that is either chemical or physical?
We also did some review on writing and balancing chemical equations
Here are some examples, try them!
1. A solution of aluminum chloride, carbon dioxide and water can be prepared mixing pure aluminum carbonate with a solution of hydrochloric acid
2. Write a balanced equation for the reaction of aqueous barium hydroxide neutralizing a solution of phosphoric acid if solid baruim phosphate and water are produced
To finish off, here's a funny video for you to watch but NEVER try at home
Yesterday, we learned about Word Equations & Balancing in chem11. However, because we were already taught this topic throughout Science 10 (last year), it was a review for most of us. But it was still a much needed review and the class was really thankful to get some practice in before going on to the "real" topics of chem11! Here are some helpful notes and reminders that Mr. Doktor gave us that day...
Phase Symbols: they indicate the phase of a chemical. So they are either solid (s), liquid (l), gas (g), or an aqueous solution which means dissolved in water (aq).
Chemical Equations from Word Equations: the main objective of this class was to learn how to understand the meaning of chemical equations, to change chemical equations into words, and finally to balance them! So, we were reminded of the diatomic seven (H, N, O, F, Cl, Br, and I) which all end with the subscript 2 when placed alone in a chemical reaction. Another good trick to remember them is that the start at the atomic # 7 and form the shape of a seven when you look at them on the periodic table, minus hydrogen. Also, we similarly learned about the polyatomic molecules found on the periodic table which are P with the subscript 4, and S with the subscript 8. The final thing that we got from that section of notes was that in chem11, a solution means something is dissolved in water. Therefore the phase is aqueous.
After we wrote down those notes, we immediately got into practicing! We went over basic balancing and analyzing word equations until the very end of the class. We were also given some more homework to do at home regarding balancing and word equations from our textbook. SO, over all Tuesday was a very productive day for Mr. Doktor's chem11 students!
Here's a helpful video on the basics of Balancing:
Today's topic was Safety; to start off the class we went into groups and discussed things that could be hazardous in a science class when doing an experiment. After listening to the other group's ideas we split into groups of 3 or 4 and had to look inside Lab drawers to see if we could find any lab equipment from a previous handout. Given that it was Friday the classes were shortened so for homework we had to find out what each WHMIS symbol meant. For fun and lab safety tips we watched a FUNNY lab safety video :)
Here are 10 smart safety tips we learned from the funny video and from our text book:
1. Wear the proper safety equipment
2. Don't forget to tie long hair back!
3. If something bad/dangerous happens, warn your teacher imediately
4. No open toed shoes
5. No horseplay
6. Listen to the teacher's instructions and follow them very carefully
7. Don't mix chemicals unless asked to do so
8. Waft, don't inhale
9. Don't ever leave an open flame
10. Know the locations of the safety materials in your lab
If you'd like to watch the video yourself here's the link ^
