Ch.8 Atomic Structure

First of all,  before we start the chapter, better do some REVIEW!

There is 3 different type of Subatomic Particles in an element

Proton: Large with positive chargeElectron: Small with negative chargeNeutron: Large with no charge

Moreover:

"# of Atomic number = # of Proton = # of Electron"

"# of Neutron =  Atomic mass - Atomic number/ Proton/ Electron"

Let's do some excerises:

Carbon:

Atomic number : 6  = Proton : 6 = Electron : 6  Atomic Mass: 12

Neutron: 12 - 6 = "6"

Rutherium:

Atomic number: 44 = Proton: 44 = Electron: 44 Atomic Mass: 101

Neutron: 101 - 44 = "57"

Bromine:

Atomic nimber: 18 = Proton: 18 = Electron: 18 Atomic Mass: 80

Neutron: 80 - 18 = "62"

Then now we can move over to Isotope,
Isotope is an atomic specie that has the same atomic number with different atomic mass.

let use Carbon as an example:

It has shown that Carbon has different Atomic mass as 12, 13, 14

So that we can indicate them as Carbon - 13, Carbon - 14

Why dont we take a look this video to see how's isotope practice works?

Theoretical Yield and Percent Yield, Purity.

Realistically, there is no reactions can be 100% completion. That's why we have to calculate the percentage of product actually formed.

As we have leaned stoichiometry calculation to predict what's the product by converting from one reactant to another reactant, and now we can determind what's the difference between

ACTUAL YIELD and THEORETICAL YIELD

   Actual Yield         (What you ACTUALLY obtain from the reaction)

Theoretical Yield    (What you EXPECT to get from the reaction)

So, when we want to find out what's the difference between "ACTUALLY YIELD" and "THEORETICAL YIELD". We can do it mathematically by mutiplying 100%

Actual Yield (What you ACTUALLY obtain from the reaction)    x   100%

Theoretical Yield (What you EXPECT to get from the reaction)

As a result, the percentage that you get will be the PERCENT YIELD.

Ex 1)

35.0 mL of 2.00 M Ca(OH)2 produced only 3.92 of CaCl2. What would the percent yield of the reaction be?

1)First, we have to consider what are the steps to get to the answer.

If we get mL (Volumn) and M (Molarity), then we can get the mol (mole) by the molarity equation WE 'VE LEARNED BEFORE.  (BETTER REVIEW)

2M x (      35    ) (L) = 0.07 mol of Ca(OH)2 x 1 mol of CaCl2         x     (40.1 + 35.5x2)

               1000                                                      1 mol of Ca(OH)2           1 mol of CaCl2

= 7.7777g of CaCl2

Actual Yield   3.92g of CaCl2              x  100%   = 50.4% (SIGFIG)

Theoretical Yield    7.78g of CaCl2





Part2       Percent Purity 

The ratio of the mass of pure substance to mass of impure sample expressed as a percent!

% Percent Pure = Mass of Pure Substance  x 100%

                             Mass of Impure Sample

By following this equation, the impure sample is heavier than the pure substance, as the impure one contains other substances in it. Once you get the answer over 100%, then you may make a mistake in your calculation.

Limited and Excess Reactants Persent Yield

As we are making up a product, there always have a need of reactant.
Sometimes, it'll have excess quantity(it will be left over) or either limited reactant ( used up completely)
that determining those reactants are completely involving in the reaction or not.

Ex 1:)
How much of which reactant will be left over?
2.19 mole of H2 is reacted with 3.48 moles of Cl2 to form HCl.

1: We have to write down the equation  H2 + Cl2 => 2HCl (make sure it's balance!)
2: Convert H2 and Cl2 into HCl by using stoichiometry calculation.

2.19 mole of H2x _2_mole of HCl    = 4.38 moles of HCl       (Limited reactant as it's less than Cl2)
                               1mole of H2

3.48 mole of Cl2x  2_mole of HCl     = 6.96 moles of HCl       (Excess quantity as it's more than H2)
                               1  mole of Cl2

3: Calculate the different between them.    6.96 - 4.38 = 2.58 (it'll be the final answer of the left over)