Gases & Moles

(Thursday, Oct 22, 2009)

continuation of the mole..



This class we learned that the volume is occupied by a certain mass depends on the temperature and pressure. The Standard Temperature and Pressure (STP) is temperature = 0 degrees Celsius and pressure = 101.3 kPa. The volume of any gas at STP is 22.4 L for every mole.

22.4 L / 1 mol OR 1 mol / 22.4 L

Examples:

- Finding the volume (L) occupied by 0.0606 mol of CO2 at STP
*Multiply by 22.4 L / 1 mol
0.060 mol x (22.4 L / 1 mol) = 1.3 L

- Finding the mass of a 200.0 mL sample of NO2 at STP
*Multiply by 1 mol / 22.4 L, but mL must be converted to L. Note that NO2 has 46 g / mol.
200.0 mL x (1 L / 1000 mL) x (1 mol/ 22.4 L) x (46 g / 1 mol) = 0.41 g

Here's a website I found that can calculate STP: http://www.1728.com/stp.htm

That is all. Mr. Doktor is the best!

-- Jael Lumba

The Molecular Mass!

(Tuesday, Oct 20, 09)

Today we learned about the mole! A mole is the number of atoms f that element equal to the number of atoms in exactly 12.0 grams of carbon-12.

- For example, 1 mole of Carbon (c) atoms is 12.01 g,

- and 1 mole of Calcium (Ca) atoms is 40.1 g.

For the diatomic molecules, plus phosphorus and sulphur, are however different when not joint into a compound. The diatomic seven (hydrogen, oxygen, nitrogen, chloride, bromine, iodide, and fluoride) have 2.

- For example, hydrogen is 2, therefore 2(1.0 g) = 2.0 mol.

- Another example is oxygen. Oxygen is 2, therefore 2(16.0 g) = 32.0 mol.

When finding the molar mass in compounds, the molar mass of all atoms must be added:

- H2o (water) has 2 hydrogen atoms and 1 oxygen atom. The mass of hydrogen is 2(1.0 g) = 2.0 mol and oxygen is 1(16.0 g) = 16.0 mol. Together, the molar mass of the compound is 18 mol

To find the mass in moles of a compound we use g/mol. To find the number of moles in a compound we use mol/g. For example:

- To find the mass of 2.5 moles of water..
2.5 mol of H2O x (18.0 g / 1 mol) = 45 g
H = 2(1.0)
O = 1(16.0)
= 18.0 g / mol

- To find the number of moles in a 391 g sample of nitrogen dioxide..
391 g of NO2 x (1 mol / 46 g) = 8.5 mol
N = 1(14.0)
O = 2(16.0)
= 46 g / mol

Here's a handy clip in finding molar mass:



That is all. Mr. Doktor is the best!

-- Jael Lumba

2-4 Elements and Compounds

Today's class we did two main experiments. The pickle electroloysis and the sugar and sulfuric acid dehydration demonstration. We saw in the pickle electroloysis what happens when the compound splits apart into its constituent elements. The sugar and sulfuric acid dehydration was by far the highlight of the class. When Mr. Doktor first added the sulfuric acid and the sugar turned a brownish colour, it really wasn't all that exciting. Without warning however, the sugar rose up as a black solid and gave off a strong scent which had everyone coughing and laughing. Following the two demonstrations, I had to leave for volleyball so I wasnt there for the acids and bases notes. I'll be getting the notes from Jarren so those will be put up soon. Here is a quick video that re-enacts our dehydration demonstration. http://www.youtube.com/watch?v=uaB70TgLfqs

That is all. Mr Doktor is the best!

Michelle Haughian

2-4 Elements and Compounds

Todays class we focussed on four main concepts: Hydrates, Naming Hydrates, Molecular Compounds and Naming Molecular Compounds.

I. HYDRATES
1. Some compounds can form lattices that bond to water molecules; without water the compound is often preceded by 'anhydrous'.
Example: Copper Sulfate 2. Those crystals contain water inside them which can be released by heating.

II. NAMING HYDRATES

1. There are three simple steps to naming hydrates:

a. write the name of the chemical formula.

b. add a prefix indicating the number of water molecules.

c. add "hydrate" after the prefix.

Examples:

1. Cu(SO4) 5H2O= Copper (II) Sulfate pentahydrate

2. Li(CLO4) 3H20= Lithium Perchlorate trihydrate

3. Nickel (II) Sulfate hexahydrate=NiSO4 6H20

TABLE OF PREFIXES:

1-mono

2-di

3-tri

4-tetra

5-penta

6-hexa

7-hepta

8-octa

9-nona

10-deca

III. MOLECULAR COMPOUNDS

I couldn't get the video to embed as well...enjoy!

http://www.britannica.com/EBchecked/topic-video/108614/109656/Molecular-compounds-are-formed-when-molecules-such-as-those-of

1. they are covalent; 2 or more non metals

2. low melting and boiling points

3. they share (not exchange) electrons

4. elements usually end in -gen

5. 7 molecules are Diatomic

a. 2 of the same elements

b. H2, N2, O2, F2, Cl2, Br2, I2

6. 2 molecules are Polyatomic

a. P4, S8

IV. NAMING MOLECULAR COMPOUNDS

In class we all decided that we knew how to name molecular compounds so we just did a few examples on the board.

1. N2O4= Dinitrogen tetraoxide

2. CS2= Carbon disulfide

3. P4O10=Tetraphosphorous decaoxide

4. Nitrogen trichloride= NCl3

5. Sulphur dibromide= SBr2

6. Dihydrogen oxide= H2O

IUPAC NAME FORMULA

1. Water H2O

2. Hydrogen Peroxide H2O2

3. Ammonia NH3

4. Glucose C6H12O6

5. Sucrose C12H22O11

6. Methane CH4

7. Propane C3H8

8. Octane C8H18

9. Methanol CH3OH

10. Ethanol C2H5OH

11.Ethane C2H6

That is all. Mr. Doktor is the best!

Michelle Haughian

2-4 ELEMENTS AND COMPUNDS (cont.)

Because our previous class was shortened, we continued our lesson by learning:

There are many methods in seperating mixtures. Depending on the type of mix, possible methods of seperating mixtures include

• By hand


• Filtration


• Distillation


• Crystallization


• Chromatography

Some elements use Latin. But, there are a few exceptions. Some of those exeptions include:

• Copper= Cuprum


• Gold= Aurum


• Iron=Ferum


• Lead= Plumbum


• Silver= Argentum

Naming chemical compunds is a difficult task. But, the most common system is the IUPAC

• IONS


• BINARY IONIC


• POLYATOMIC IONS


• MOLECULAR COMPOUNDS


• ACIDS

When naming ions, remember that for metals: use the name of your element and add ion. For non-metals, remove the original ending and ade -ide.

Binary Ionic Compounds contain two elements (one metal and one non-metal)

• Metallic and non-metallic bond together
• Electrons trasnfer from metal to non-metal
• Net charge=0 ( total positive charge=total negative charge)

That is all. Mr. Doktor is the best!

BY: Krizia Umali