How to Name Acids

Acids are formed when a compound compsed of hydorogen ions and negatively charged ions become an aqueous or dissolved in water.

*Note: all numbers underlined are subscripts.

In water, these ions separate when dissoved. Also hydrogen ions join with H20(water) to form H30 (hydroniums)



Eg. H+ Cl - => HCl

       HCl (g) +H20 => H30 (aq)  + Cl (aq)

Guidelines in Naming Acids:

For columns 16 and 17, use simple acid formulas.

1. Use "hydro" as the beginning

2. Last syllable of the non metal is dropped and replaced with -ic.

3. Add "acid" at the end

* ________ide  → hydro___ic acid

Eg.

1. HF(aq)  -  hydrofluoric acid

2. HCl(aq) -  hydrochloric acid

3. HBr(aq) - hydrobromic acid

4. HI (aq)  -  hydroiodic acid

5. H20 (aq)  - water  :D

6. H2S (aq) - hydrosulphic acid

7. H2Se (aq) - hydroselenic acid

Written by : JK (Oct 14, 2010)

Answers from the changes in matter questions

Here are the answers:

a) physical change because fog is water vapour that is condensed into droplets of moisture

b)chemical change because new substances are formed: smoke and cancer cells-causing chemicals)

c)chemical change because the growth involves chemicals being produces and used up

d)chemical change because rust is a new substance formed by combination of iron, air and water)

e)physical change because no reaction has occurred to make new substances

f) physical change because we are only separating substances, not producing new ones

If you got perfect, you are ready to go but if you got less than 4 you need to study... :(

Written by JK

Changes in Matter

There are 2 main changes in Matter : Physical and Chemical

In a Physical Change:

no new substance is formed

the chemical composition does not change

it is reversible (you can drink water(liquid) if you melt ice :)

Eg. boiling point, melting point

In a Chemical change:

it is irreversible (you can't undo a salad dressing)

new substances are produced

Eg. burning, cooking

So these are the basic changes in matter

Here are some questions that you can answer.

Classify each of the following as either chemical or a physical change

a) formation of a fog
b)burning a cigarette
c)sprouting of a seed
d)rusting of iron
e) mixing yellow and blue paint to make green paint
f) separating an alcohol- water mixture into water and alcohol

The answers will be up shortly!

Written by JK

All About Matter!!

Do you guys know what matter is??

(you say: NO, what is it??)

Matter is anything that has mass and volume a.k.a everything around us

MATTER can be broken down into 2 categories:



Calcium

PURE SUBSTANCE:  only one set and kind of properties

MIXTURES: more than one set of property and substance

                       physically combined

These categories can be broken down further.

PURE SUBSTANCES can be broken down to 2 more categories

ELEMENTS: simplest form (cannot be decomposed) and made up of atoms

                         ie. metals, metalloids, non-metal

COMPOUNDS: made up of elements

                              chemically combined

                             smallest particle (molecule)

     

                         ie. ionic, covalent

MIXTURES can be broken down to 2 more categories.

HOMOGENEOUS MIXTURES:

uniform throughout

appears to have only one component

ie. solution

HETEROGENEOUS MIXTURES:

not uniform

appears to have more than one component

ie. water and oil, salad dressing

can be broken down further to : SUSPENSION, MECHANICAL MIXTURE

In conclusion,

I hope that you guys unders

How to Do Unit Conversions (PART II)

Hello, we are back again.

Few days ago, we introduced the concept of unit conversions and showed you a simple example.

Today we are going to show you how to do complicated examples

Lets take this example.

Convert 50km/h to m/min

First, look at the question to find what needs to be converted.

You can see that the km and the h needs to be converted.

Before you make an equation, lets write out the conversions

10^3m = 1km  ;      60min = 1hr

Now lets make an equation.

50km x  10^3m x     1hr     =      
  1hr          1km      60min   

From here you need to cancel the units

50km x  10^3m x     1hr     =      
  1hr          1km      60min   

After you do multiplication:

                 50x10^3
                      60
and the result is 833.33 or 8.33x10^2m/min.

This is basically what unit conversions are about.

Written by Jk

Brief Review of Scientific Notation

Yesterday, we taught you the basics of unit conversion.

Today, we will guide you through more questions that are complicated but not so hard if you follow our way.

First, before we do any questions, we need to review SCIENTIFIC NOTATION.

Scientific notations are used to express really big and really small numbers such as 500billion or 0.000000000000003333 using powers of 10.

One thing to note here is that the number that is constant is bigger or equal to 1 but less than 10.

Example:

Express 25,100,000,000 in scientific notation.

First we need to make a constant number that is more than 1 but less than 10.

As you can see, I made a constant number from the original number.

In this case, the number we need is 2.51

The Next step is to count the zeros from the original decimal to the decimal of 2.51




              

 







On the above, I moved the original decimal point to the new decimal point.

As I did that I counted how many digits until the decimal of 2.51. In this case there are 10 digits.

Now you put all of it together.

Take the constant number and multiply it at the 8th power of 10

The result would be 2.51 x 10^8

I hope that you will have an easier time with scientific notations and hopefully with unit conversions.

See you next time!

Written by: JK (Sept 21,2010)

How to Do Unit Conversions (PART I)

Before we start doing any crazy chem labs and experiments, we need to learn how to do Unit conversions.

This will be fairly easy for those who are adept at math.. to those who aren't... deal with it.

First, unit conversion is simply converting the original numbers into the same number with different units.

NOTE: CONVERSION FACTOR: fractional expression relating or connecting 2 different units

I am sure that you know how many cents are in a dollar or how many minutes are in a hour.

When you change certain amount of cents into dollars (ie. 25cents →$0.25), you are also converting units.

Also, take a good look at the unit conversion table that Miss Chen gave us.

Now on to some basics:

Incredibly, vitally important NOTE:

You must ALWAYS include the UNITS. or else you will get confused and get the wrong answer.

Example 1:

If a car can go 80km in 1 hr, how far can it go in 8.5hrs?

In this question, simply do a math ratio, it is the easiest way.

                                       80km      (x)km
                                          1hr         8.5hr

From this do cross multiplication:

                                  (80km)(8.5hr) = (x)km
                                           
After you multiply you get this number 680km

This is the basics of unit conversions, part 2 coming soon

Check out this video from Youtube which gives a different but effective way of doing unit conversions:

http://www.youtube.com/watch?v=ClxIsX9JV-M

Written by: JK