More Mole Conversions

So we learned that there are 6 main mole conversions. So far we have learned only 4.

So what's the other 2?

Mole Conversion type 5:

Atoms to mass:

     # of atoms           x           1 mole               x         Mass of atom        
                                    6.022 x10^23atom               1    mole

Mole Conversion type 6: (it's the last one =D)

Mass to atoms

         Mass # (in the question)      x              1 mole            x        6.022 x 10^23atoms      
                                                             Mass of atom                       1 mole

This is the finale of types of mole conversion.

To make these kinds of questions "easier", you have to make a plan.

Always try to find the number of moles


See you next time

Mole Conversions

(Yup, there IS such a thing!!)

1) From particles <----> moles

• From particles ---> moles  

 Ex, 3.01 x 10^24  particles of C --->  mole

 3.01 x 10^24 particles   X       1 mole         =  5.00 moles

                                              6.022 x 10^23 particles

PS, Don't forget sig figs & units..

• From moles ---> particles/ molecules/ formula units

Ex, 0.75 moles  of CO2 ---> molecules

0.75 moles  X  6.022 x 10^23 molecules  = 4.5 x 10^23  molecules

                                   moles

Now, 0.75 moles of CO2 ---> atoms of O2

              4.5 x 10^23  molecules X  2 atoms of  O  = 9.0 x 10^23 atoms



2) From grams <----> moles
 

• From moles ---> grams

Ex, 2.04 moles of Carbon ---> grams

                 molar mass of Carbon = 12 g / mol
            
                 2.04 moles  x  12 grams  =  24.5 grams of Carbon
                                      1 mole

Ex, 0.341 moles of NO2 --->  grams 

       molar mass of NO2 = 46.0 g / mol

       0.341 moles  x  46.0 grams   =  15.6 grams of NO2  

                                         1 mole

• From grams ---> moles 

Ex,, 3.45 grams of Carbon ---> moles

        atomic mass of carbon = 12 grams

                  3.45 grams  x    1 mole   =  0.288 moles
                                       12 grams

Ex,, 6.2 grams of MgCl2 ---> moles

        molecular mass of MgCl2 = 95.3  grams

        6.2 grams  x    1 mole    =  0.065  moles

                                     95.3 grams

This is what we took so far.. Explain the rest next class!!! :D:D

THE MOLE

NO!   Not the animal, or the TV series, or the body thing!!!!

Soo, What is it then ???

Interesting question!

A MOLE is the amount of pure substance containing the same number of chemical units as there are atoms in exactly 12 grams of carbon-12 (i.e., 6.023 X 10^23). 

This involves the acceptance of two dictates -- the scale of atomic masses and the magnitude of the gram. 

Its a very huge number used as a relative comparison between substance. So 1 mole of a substance could weight more that 1 mole of a different chemical substance.

 

Equal volumes of different gases have a constant ratio..

ex,,   O2 : H   ---> 16 : 1        (16 & 1 are the atomic mass of the 2 elements)

          CO2 : H ---> 22 : 1

 It gets more interesting..

Avogadro's Number 

(Again, the scientific "Avogadro")

Equal volumes of different gases at the same temperature & pressure have the same number of particles. Since they have the same number of particles, the mass ratio is due to the mass of particles. 

Avogadro's number indicates that the amount of particles in 1 mole of any substance is 

6.022 x 10^23   particles / mole

By the way, relative masses of all atoms is measured in Atomic Mass Unit (aka, AMU)..  

Formula Mass

IONIC compounds >> Add AMUs

Ex,  Potassium Fluoride

atomic mass of Potassium is 39.1

atomic mass of Fluorine is 19

Therefore, 39.1 + 19 = 58.1 amu

Molecular Mass

COVALENT compounds >> Add Masses

 Ex, Carbon Dioxide (CO2)

atomic mass of Carbon is 12

atomic mass of Oxygen is 16

There are 2 atoms of oxygen..

Therefore, 12 + 16 + 16 = 44 amu

Molar Mass

Mass of 1 mole of an element.. 

Unit >> grams per mole  ( g/mol ) 

Ex, 1 mole of oxygen = 16.0 g/mol

I bet you are saying to yourself,, " myself,, what is the whole point of this??"

I'll tell you what.. IT ALLOWS CHEMISTS TO COUNT ATOMS AND MOLECULES EASIER (yes, it is a big deal!!)..


You've all heard of Mole Day,, (no, not really)...
Well it is on Oct 23rd from 6.02 am till 6.02 pm ..

Check out this Song ::

Thanks for stopping by.. ;)

Ch.3 Review

Last class, we had a review of chapter 3.


Things to know:

Significant Figures

Measurement and Uncertainty

Scientific Notation

Density

Graphing

Unit Conversion


Good luck on the Test

Density Graphs

Last class, we went to the computer lab to make a density graph of cold water and hot water.

LAB 2E!!

Hey

Last class, we did a lab from Essential Experiments for Chemistry!!

We are going to go over what we did.

Our Purpose was to use scienticfic notation and significant figures after determining both volume & density  
                            of an Aluminum sheet.

We measured the length and the width and the mass of the sheet. Then we figured out the density.

Follow up Questions

1. A rectangular metal tray (22.55cm by 15.33cm) plated with thin layerof gold (density: 19.32g/cm3).
Gold plating mass : 0.0538g. Calculate the thinkness using scientific notation and number of sig. figs.

First, write the general formula of density.

                          D =     m   
                                     V

Then plug in numbers.

                  19.32g/cm3 =   0.0538g   
                                              V
                   
                               V    =   0.0538g     
                                           19.32g/cm3

                                 V  =   2.78 x 10-3cm3

Calculate thickness or height

                         V = LWH
                 
                 2.78 x 10-3 = 22.55(15.33)H

                          H =   2.78 x 10-3
                                   22.55(15.33)

                       H = 8.06 x 10-6cm

2. 1000.0cm3 of oil. Surface area = 850.0m2. Density: 0.850g/cm3
    How thick was the oil?

Ok, first there is some irrelevant info here.

Density info is not need because we need to find height or thickness

Therefore, write equation for volume.

                   V = LWH

Dont forget to convert m to cm

                1000.0 = 8.50 x 106(H)

                    H =  8.50 x 106  
                             1000.0

                   H = 1.76 x 10-6cm

Thats it for today!

Good nite!

Written by JK Nov 4,2010

Density!!

Hi everyone!

We are going to teach you about density.

DENSITY is just mass contained in a given volume of a substance.

Before we go on, enjoy this cartoon.



Hahaha I hope you are laughing!!

Back to chemistry.

Density is represented by the formula :

                              Mass(g)      

                            Volume(cm3)

Basically, if density of an object is greater than the density of the liquid then it will sink

If the density of an object is less than the density of the liquid then it will float.

Written by JK (Nov2,2010)