Chem Class- October 30, 2009

Another lab is coming up, so today Mr. Doktor showed us what we will have to do. First we are going to fill the sink full of water. Then we will submerge a 100 mL graduated cylinder with water in the sink and then invert it, making sure there aren't any air bubbles. After that, we will place the lighter at the bottom of the sink underneath the water and graduated cylinder. We will also release butane from it so the graduated cylinder will fill up with gas. The purpose is to experimentally determine the molar volume of a gas. We will also find out what the mass of the Butane lighter is before the experiment, after the experiment, how much is used in the experiment and calculate the amount of moles of the Butane. After that, as usual, we are to calculate the percent error in our calculation of molar volume and list any factors that may have affected our results.


Notes on Atoms and Molecules.

For Monoatomic elements: A molecule = an element

Molecules and compounds: H2O = 2 "H" atoms in 1 molecule/ 1 "O" atom in 1 molecule

Conversion fator for moles to molecules and vice versa:
6.20 x 10 to the power of 23 molecules/ 1 mol or 1 mol/ 6.20 x 10 to the power of 23 molecules

Eg: How many molecues are there in 0.125 mol of molecules?
# of molecules = 0.125 mol x 6.02 x 10 to the power of 23 molecules/1 mol = 7.53 x 10 the power of 22 molecules.

Oh, and Mr. Doktor broke a wooden board in half!!!!!

Chem Class - October 28, 2009

Today in class we did the ‘Mole Ratio Lab Experiment’. It wasn’t too hard, but it took a while. It was a simple experiment but if you didn’t pay attention to how you were handling the chemicals you could have gotten hurt. The purpose was to the determine the number of moles of copper produced in the reaction of iron and copper (II) chloride, the number of moles of iron used up in the reactio of iron and copper (II) chloride, the ratio of moles of iron to moles of copper, and the number of atoms and formula units involved in the reaction.



When doing the experiment you had to be careful with the chemicals. Copper (II) Chloride and 1Mhydrochloric acid.

Copper (II) Chloride                            1 Mhydrocholirc acid

If you came in contact with either of them you would have to rinse the affected area with water. The chemicals should never be touched, tasted, consumed and inhaled directly in any way! We wore our safety goggles and lab aprons.

The main point of the experiment was to find the difference of ratio of moles of Iron to copper. We mixed the Copper (II) Chloride with distilled water, and it turned into a light blue color.

 Copper (II) Chloride mixed with distilled water

After that we added two Iron nails and waited 20 minutes for the results.

After waiting 20 minutes we took out the nails from the solution and examined them. We saw that they were covered in copper. We then scrapped off the copped back into the solution then placed the nails to dry.

We then separated the Copper (II) Chloride solution and the leftover copper, then rinsed the left over copper with 1Mhydrochloric acid. We dried the left over copper and weighed the nail and dry copper. After recording out results we dumped the left over chemicals in a chemical container that would be disposed of later on and cleaned up our lab materials. Then we washed our hands.

You can find the lab on page 55 of the Heath Chemistry (Laboratory Experiments-Canadian Edition) text book. Give it a go yourself!

Chem Class- October 26, 2009

We've added on to what we've learned today with GASES AND MOLES.
The volume of a baloon occupied by a certain gas depends on the temperature and pressure.

Standard Temperature and Pressure (STP)
O degrees Celcius and 101.3 kPa (or 273 k)

Recall Standard Ambient Temperature and Pressure (SATP)
25 degrees Celcius and 100 kPa (or 298 k)

The volume of 1.0 mole of any gas at STP is 22.4 L
The Molar Volume at STP is 22.4

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Conversion Factors: 22.4 L/1 mol or 1 mol/22.4 L (At STP only)

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Example: Find the volume at STP occupied by 12.5 mol of NH3 (g)
Volume= 12.5mol x 22.4 L/1 mol =2.80 x 10 to the power of 2 L.

Example: Find the number of moles of 375 mL of SO3 (g)
# of moles = 375 mL x 10 the power of negative 3 L/ 1 mL x 1 mol/22.4 L = 0.0167 mol

Chem Class- October 21, 2009

We've now moved on to calculations of molar mass and moles. First though, Mr. D checked our homework that was assigned last class and then we went over number 5. The question for that asked what the purpose of using a satndard term to describe a certain number was. It's basically created to abbreviate something, making it more convenient, faster and easier.
Also: " Mr. D stole my noodles :(.... but I got dem back :)"

Ok, back to Chemistry. First of all, we started with the Atomic Mass.

The atomic mass is the mass of one mole of atoms in an element. It is also the mass of 1.0 mole of 'C' atoms in 12.0 g  (Eg: The mass of 1.0 mol of 'Ca' atoms is 40.1 g).

Molecular Mass is the mass of 1.0 mole of molecules of an element or a compound.
It's good to remember those that are diatomic: N2, O2, F2, CL2, Br2, I2, Hr (the special seven)
It's also good to remember those that are polyatomic: P4 and S8
You can assume, now, that all the rest are monoatomic

Finding the Molar Mass of Compounds
Eg: Find the molar mass of Ammonium Phosphate

NH4(+) and PO43(-) is (NH4)3PO4
3 N = 3(14.0)
12 H = 12(1.0)
1 P = 1 (31.0)
4 O = 4 (16.0)
          _______
          149.0 g/mol

Converting Mass<----->Moles
Conversion Factor g/mol or mol/g

Eg: Find the mass of 2.5 mol of water
1mol/18.0g x 1/2.5 mol = 1/45 g =45 g

Eg: Find the number of moles in a 391 g sample of Nitrogen dioxide
NO2
1 N = 1(14.0)
2 O = 2 (16.0)
         _______
          46.0 g

391 g x 1 mol/46 g = 8.5 mol

Chem Class- October 19, 2009

Last class we had our test for Unit 2 and today we got our test back. We hope everyone did well!
After that, Mr.D did a small balloon experiment:

Now we're on to something new!

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Today we were introduced to the Mole.

Now let's get this straight. We're not talking about the kind of burrowing animal or the so called 'beauty spot', but the SI unit for the amount of substance . It is equal to the number of atoms in exactly 12.0 grams of carbon-12 (6.02 x 10 to the power of 23)

1 mole is equal to 602 000 000 000 000 000 000 000 or 6.02 x 10 to the power of 23. This is a really big number and it is known as Avogadro's number. Let's say we had that number equal to dollars. If we divided that number up among the six billion people on Earth, every person would have $100 000 000 000 000 each.

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Many people tried to see how gases could combine. John Dalton, for example, looked at masses of gasses but he could see no pattern:

• 11.1g of H2 reacts with 88.9g of O2
• 46.7g of N2 reacts with 53.3g of O2
• 42.9g of C reacts with 57.1g of O2

The reason he couldn't see a pattern is because 1 molecule of H2 doesn't have the same mass as 1 molecule of O2.

Joseph Gay-Lussac tried combining gases on volume:

• 1 L of H2 reacts with 1 L of Cl2----->2 L of HCl
• 1 L of N2 reacts with 3 L of H2----->2 L of NH3
• 2L of CO reacts with 1 L of O2----->2 L of CO2

As you can see, gases combine in simple whole number ratios.

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AVOGADRO'S HYPOTHESIS
Equal volumes of any gas at a constant temperature and pressure contain equal numbers of molecules.

Chem Class- October 13, 2009

Today we did a lab on hydrates. We weighed our empty test tube, then our teacher put a hydrate inside. We then used our bunsen burner to evaporate all the water out of the hydrate. It went from a fushia, to a light blue. About 45% of the water in the hydrate evaporated, which was the accepted value. Finally, we calculated our percent error (measured-accepted/accepted). The purpose of the experiment was to determine the empiracle formula of a hydrate.

When it comes to lab safety, we need to be aware that we are using a bunsen burner. This means that long hair should be tied and sleeves should be rolled up so that it doesn't catch on fire. We are also dealing with glassware so it needs to be handled with care and broken glassware should not be used. In addition, we are  electrical equipment is being used (electrical scale) and so it should not be unplugged by pulling on the chord. Finally, we should also wear safetly goggles and a lab apron.

For our lab, the mass of the hydrate (calculate by subtracting the mass of the test tube) was 1.0 g. The mass after heating was 0.6 g which meant that 0.4g of water was realsed during the heating and 40% of the hydrate waswater. Our percent error was 11.1%.

We also have our test coming up for this unit.
60% of the test will be mainly naming chemicals (Chemical Nomenclature):

• Ionic
• Polyatomic
• Multivalent (IUPAC and Classical-Latin)
• Molecular
• Acids/Bases
• Hydrates
• Ions

The other portion of the exam will consist of the classification of matter (Heterogeneous and Homogeneous substances) and separating mixtures (Chromatography, Crystalization, Distillation, Filtration, by hand...)

Chem Class- October 8, 2009

Let's get started for the day. Today we:

- Handed in homework

- Got our marks for our blogs for the first unit

- Mr. D did a demonstration lab that involved combining sugar (C12H22O11) and Sulfuric Acid (H2SO4). Smoke came out and the substance inside turned black (carbon) and slowly rose out of the beaker. A very strong smell of burnt sugar or raisins was produced.

Equation for experiment: C12H22O11 + H2SO4 -----> C(s) + H2O +  S

Actually, you can observe the experiment yourself without having to smell the results. Here's a youtube video:

Down to the notes now. Acids and Bases. What are acids and bases? Let's start with acids.

SATD stands for standard ambient temperature and pressure which is 25 degrees Celcius and 100 kPa.

NAMING ACIDS

• 
  
  It's also good to know that acids are aqueous (dissolved in water). Hydrogen compound are acidic (Eg: HCL (aq)-----> Hydrochloric Acid and H2SO4(aq)----->Sulfuric Acid)
  
  
  
• 
  
  Hydrogen appears first in the formula unless it is part of a polyatomic group (Eg: CH3COO----->CH3COOH/Acetate becomes Acetic Acid).
  
  
  
• 
  
  Classical rules use the suffix -ic and/or the prefix hydro (EG: HBr = Hydrobromic acid and HI = Hydrochoric Acid).
  
  
  
• 
  
  IUPAC uses the aquesous hydrogen compound (EG: HCL(aq)----->Aqueous Hydrogen Chloride)
  

Now, what are bases?

Naming Bases

• 
  
  For now, all bases will be aqueous solutions of ionic hydroxides
  
  NH3 is an exception. Even though it does have OH at the end, it is a base.
  
• 
  
  You Use the cation name followed by hydroxide
  
  
  
• 
  
  (NaOH----->Sodium Hydroxide and Ba(OH)2----->Barium Hydroxide).
  
  
  

Chem Class- October 6, 2009

Today in class Mr. D showed us a demonstration. There were two test tubes and each of them had something in them. One of them was white and one of them was purple. Mr. D used the Bunsen burner to heat up the purple one and it turned blue with a bit of moisture. Cool or what?

After that, we went over our homework which was the work sheet for naming compounds. Then we did some notes. Luckily, they weren’t that long!

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More Chemical Nomeclature!

First of all though, we must learn about hydrates.
Hydrates are substances that contain water.
Some compounds can form lattices that bond to water molecules (Eg: Copper Sulfate, Sodium Sulfate).
These crystals contain water inside them which can be released by heating. Without water, the compound is often preceded by Anyhydrous (Eg: Copper (II) Sulphate) just to make it clear that it is not a hydrate.

To name Hydrates:

1. Write the name of the chemical formmula
2. Add a prefix indicating the number of water molecules
    3. Add hydrate after the prefix

Examples: Cu(SO4) . 5H20(s)----->Copper (II) Sulfate Penta Hydrate
                 Nickel (II) Sulfate hexahydrate-----> NiSO4 . 6H2O(s)

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Molecular Compounds

- Composed of two or more non-metals

- Have low melting points and boiling points

- Usually end in -gen or -ine (EG: Hydgrogen, Oxygen and Nitrogen)

- 7 molecules are diatomic (H2, N2, O2, F2,Cl2, Br2, I2) which means that they have two of the same element

- 2 molecules are polyatomic (S8 and P4) which means that they have more than 2 (many) of the same element

Examples

N2O4----->Dinitrogen Tetraoxide

P4O10----->Tetraphosphorous decaoxide

Nitrogen Trichloride----->NCl3

Sulphur Dibromide----->SBr2

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These molecular compounds are very common and have names that don't follow the same rules for naming:

Water is H2O

Hydrogen Peroxide is H2O2

Ammonia is NH3

Glucose is C6H12O6

Sucrose is C12H22O11

Methane is CH4

Propane is C3H8

Octane is C8H8

Methanol is CH3OH

Ethanol is C2H5OH

Chem Class- October 2, 2009

Ah yes. Chemical Nomenclature. This is all about naming chemical compounds. Different systems have been used through the enturies but the most common system today is IUPAC (International Union of Pure and Applied Chemistry) for most chemicals.

• Ions
• Binary Ions
• Polyatomic Ions
• Molecular Compounds
• Acids

Be careful when dealing with superscripts and subscripts. Superscripts refer to the number that is beside and above the symbol, representing the ion charge while subscripts refer to the number that is beside and below the symbol, representing the number of ions.

The first two columns in the table below contain symbols with superscripts while the last column represents symbols with subscripts (look at the numbers).

You probably noticed the two terms: Cation and Anion. Cations are ions with positive charches while Anions are ions with negative charges.

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When it comes to naming ions, use the name of the element and then add ion for metals (Al3+ becomes Aluminum Ion) and simply remove the original ending and add -ide for non metals (F- becomes Fluoride).

Below is a table of polyatomic ions which have special names:

Here's a youtube video on how to write the formula for Binary Ionic Compounds. It's pretty good on listing the steps and providing a visual example of a lewis diagram for why the compound is written the way it is:

Some elements can form more than one ion and they are called Multivanet Ions. The more common ion is the top one of the Periodic Table. IUPAC uses Roman numerals in parenthesis to show the charge (I, II, III, IV, V, VI, VII)

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Finally, Classical Systems use Latin names of elements and the suffixes -ic for larger charges (Eg: FeO----->smaller charge-----> Ferrous Oxide) and -ous for smaller charges (Eg: Fe2O3----->larger charge----->Ferric Oxide)

Other Classical Names

Ferr-Iron

Cupp-Copper

Mercur-Mercury

Stann-Tin

Aunn- Gold

Plumb-Lead