Tuesday, January 26, 2010

Jan 25-26 Reaction Rates

Today in class we started by identifying different types of chemical reactions (synthesis, decomposition, single and double replacement. We then reviewed the hints to balancing chemical equations.

We then performed a lab that looked at the effect temperature has on the speed of a chemical reaction. We found that if we compared the reaction of an alka-seltzer tablet in cold and hot water, the hot water had a much faster reaction rate.

We then looked at the effect of surface area on reaction rates. We found that if we increased the surface area by crushing the object, the reaction would speed up. We then discussed the effect of concentration on reaction rates.

Remember--the test will be this friday--study guide is available online on my website (go to the tests and quizzes section).

Wednesday, January 20, 2010

Jan 19th and 20th--naming ionic and covalent compounds

Today in class we went over some rules for naming compounds--then we named some.

The notes from today's class are below:

Tell me (in your notebook) as much as possible about the following chemical formula. Ba(NO3)2

(how many atoms of each element, how do you think it bonds, could you draw the structure?)

Follow-up question. If the formula breaks up into its ions, what are the charges of the Ba and the NO3?


Naming Covalent compounds.

Copy the prefixes on page 31(mono, di, tri, etc)
Put the element symbols in the order they are in the periodic table -but-

Hydrogen would fit between nitrogen and oxygen.

Use the prefixes to name them - but you usually don't use a prefix for the first element in the formula. The prefixes tell you how many atoms of each there are.

drop the 'a' and 'o' from the prefix when attaching the prefix to oxide. Ex CO is carbon monoxide

Naming Ionic Compounds

• The positive element (the metal) goes first.

• The positive one gets to keep its name.

• The negative one gets ide attached to the root of the name.

• (think sodium chloride)

To find out how many of each ion to use, first figure out the charge of each ion (see chapter one)

Then criss-cross the charge numbers.

Example: figure out the formula for a substance made from magnesium and chlorine

Mg, the charge is +2, Cl the charge is -1

Flip flop the charges and the formula is MgCl2

Determine if ionic or covalent, then write the formula for these compounds.
sulfur trioxide

calcium fluoride

phosphorus pentachloride

dinitrogen trioxide

lithium oxide

Monday, January 11, 2010

Jan 11-12

Today in class we investigated conservation of mass in a chemical reaction. We reacted an alka-seltzer tablet with water and measured the mass of the closed system before and after the reaction.

We also started to balance chemical equations--please review chapter two sections one and two after today's class.

Monday, January 4, 2010

Jan 4-5 2010

Welcome back from winter break!

We dove right into chemical reactions (chapter two) and started off with a reaction that combined HydroChloric Acid (HCl) with Magnesium (Mg). When the two were mixed we saw bubbles of gas and noted that the flask that held the HCl became warm to the touch.

We wrote out the equation as HCl + Mg --> H2 + MgCl2

We noted that this was NOT a balanced equation.

We then collected the gas in a balloon and ignited it. We saw a large fireball.

We then wrote down the equation H2 + O2 --> H2O, again we noted that this was not a balanced equation.

We then completed the start up activity on page 27 then watched some of our commercials.