3 Question (10-26-12)

This week I finish the Avogadro’s # lab and celebrate Mole Day by creating s big poster about Avogadro with a body of a mole
I just learned how to go from grams in a chemical reactions to molecules, like how many oxygen molecules in O2 +2H2--2H20
Next week i would like to learn more about Stoichiometry and learn the last section.

My Book

I haven't read my book, but the little i read is about the science about dunking doughnut and cookies. What is a cookie and a doughnut made of and what happens when you put in a coffee.

The Mole

A "Mole" is just a number, its the amount of a chemical substance. With the symbol "Mol" is like grams or amu, just use moles instead of grams or amu and it would be the same amount. The number of molecules in a mole is 6.022X10^23 ( Avogadro's number).
http://www.moleday.org/

3 Questions of the week

Today at class we did a lab called "Avogadro's number". Counting, getting the mass and volume of 100 rice grains, to get an idea of Avogadro's number
This week i just learned that a mole is just a number of a amount of a substance 6.022X10^23 ( Avogadro's number)
Next Im planning to learn more about Avogadro's number and celebrate National Mole Day (10-23-2012)
http://www.moleday.obrg/

Accurate, Precise and Significant Digits

Accuracy is how close a measured value is to the actual value.
Precision is how close the measured values are to each other.

Significant Digits rule: Atlantic Vs.Pacific
Atlantic- if decimal is Absent, count  all numbers from the right (Atlantic) with the first nonzero to the left
Pacific- if decimal is Present, count all numbers from the left (Pacific) side with the first nonzero to the right

 

Percent Composition

       To find the  Percent Composition you first have to find the Formula weight: the sum of the atomic mass for the atoms in a chemical formula. Then you divide part over whole times one hundred. which the "Part" is the element you want to find in a formula. The "Whole" is the compound or the formula weight of the chemical formula, then times 100 because its a percent.
Ex: Find aluminium in Al₂(SO₄)₃

Formula Weight:    (2)(Al)-   (2)(26.9)=    53.8                                     53.8gAl
                                (3)(S)-    (3)(32.1)=    96.3          % composition-------------------- X100
                               (12)(O)- (12)(15.9)=  190.8                                   340.9gAl₂(SO₄)₃
                                                      Total= 340.9
% composition= 15.8%. there's 15.8% of Aluminium in the formula Al₂(SO₄)_3.