Two Unit Conversions

like the single unit conversion, this one has the added step the you must make in order to accumulate the right answer. Sometimes the two step conversions can be confusing; a good way to keep track of all your steps is to make a map. For example:

cm-> m-> km or km-> m-> cm

Most important! know your Conversion factors well! Mixing these up will always

get the wrong answer. Not even that, factors wouldn't be able to cancel out, therefore not even getting an answer. You might even multiply in the wrong places where they shouldn't.

Term of the day: Derived Quantity Conversions

When there more than one SI base unit in a single quantity. For example: 20m/s, 2.34dg/ms, or 10km/h

Trying out the two step conversion:

convert the rate 0.075s/km to m/h

maps: km->m & s->min->h

0.075s/km x 1000m/1km x 1min/60s x 1h/60min = 0.0208m/h

check below for more examples from the classroom:

Just a Quick Recap on Quantities and Unit Conversions

Last class we learned the fundamental basics towards futher understanding of chemistry. First we learned that quantities always have two parts-the number and the unit.
                                                    ex. 15 m, 40 s

The units we use derive from the SI (Système Internationale) which is a French system that is based upon using powers of ten. The following are the units:

Conversions aren't as complicated as we think! With the help of the "magic one", conversions are made simpler. Also, when converting, we always want to put the SAME units across from each other. That way, they are able to cancel each other out:

                                                          ex. 500cm into m
                                                                 5
                                                                 500 cm x   1 m       
                                                                     1         1 100 cm   = 5 m
Here are more examples using scientific notation:

Prevent Yourself from Becoming the Spongebob in the Story- Safety

As we are in a chemistry class, its important to be aware of all the harzards.  WHMIS, or Workplace Hazardous Materials Information System is an international system that educates people about the dangers of the chemicals they are working with.

MSDS, or Material Safety Data Sheets are labels that can be found on all the chemical containers we will be working with this year.  Here are some of the thing they can tell you:

WHMIS Symbols



Compressed Gas

- gas under pressure

- heat or having the container dropped may cause it to explode

- the gas isn't toxic unless there is another WHMIS symbol which will tell you the hazards

Flammable and Combustable

- can burn at a low temperature- even sparks can cause it to ignite

- several divisions: flammable gases, flammable liquids, combustible liquids, flammable solids, flammable aerosols, and flammable reactive materials(can ignite either in air or water)

- KEEP AWAY FROM HEAT!

Oxidizing Materials

-they release oxygen, or another chemical which will result in a similar effect, that helps fuel the fires of other flammable or combustible objects

- fire and explosion risk

- NEVER SMOKE NEAR CHEMICALS and wear proper protection(lab coats, goggles, etc.)

Poisonous and Infectious

- contact with chemicals have immediate and serious effects

- can easily kill you

- can be classified as very toxic or toxic

- either way, wear appropriete clothes on a lab day and be sure to wash your hands afterward

-Materials causing other Toxic Effects

- although they are poisonous, they don't have immediate effects

- exposure to the chemicals over long periods of time may leave permanent damage(cancer, birth effects, etc.)

- work in well ventilated areas

-Biohazardous Infectious Material

-organisms like bacteria and viruses which produce toxins which are thought to be responsible to diseases like HIV

Corrosive Material

- caustic or acidic chemicals which corrode (aluminium, flesh)

- can be gases or liquids(ammonia, sodium hydroxide)

Dangerously Reactive Materials

- things like heat, presure, etc. cause some materials to have dangerous reactions(e.g. decomposition)

International Safety Symbols

Not everyone uses WHMIS symbols.  The International Safety Symbols have similar pictures, but the amount of sides the picture is surrounded by determines how dangerous the material is.  They come in octagons, diamonds and triangles.  The more sides, the more dangerous.

Safety in the Science Classroom

Much of safety is common sense.  However, to prevent a situation like Spongebob's experiment, let's review.  Here is a basic list of things to remember.

1. Always read the lab instructions before you start.
2. Clear your area of papers, books, and clutter.
3. Tie back long hair and wear closed toed shoes.  Wear your goggles over your eyes.  Lab coats must be done up.
4. Never eat in a science classroom.
5. Never leave your station unattended(Bunsen burners, open chemicals, etc.)
6. Never use unlabelled chemicals.
7. Check for chipped materials before you start the lab.
8. Don't run.
9. Never put used chemicals into the bottle from which they came. They could be contaminated.
10. Never pour them down the drain either unless the teacher says so.
11. Know where the first aid equipment and other emergency things are located(fire blanket, safety shower, fire alarm, emergency exit, phone, eye-wash station, first aid kit, etc) in your classroom.
12. Wash and dry your work area and all the materials you used.  Put them back exactly where you got them from.
13. Put broken glass in the broken glass bin.
14. Add acid to water, not the other way around.
15. Be aware of hot plates and Bunsen burners.  Never reach across open flames.  Hot plates may not appear hot, but they stay hot for up to an hour and will burn you.
16. Don't let anything boil until it has dried up.
17. Waft vapours toward you, don't directly sniff the substance.
18. If you are burned, or have splashed chemicals onto your skin or eyes, run them under cold water for 15 mins and then tell your teacher. 
19. Apply pressure to cuts to stop bleeding.
20. Identify the chemical.

If you get a job, make sure you know the hazards of your position.  Teens have the highest rate of being injured on the job in BC. 

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Now that you have had a review, draw in the background of the following picture with things that you shouldn't do during a lab.