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Test Question

Posted: Tue Oct 08, 2019 7:34 pm
by JohnWalkiewicz2J
Some problems in the textbook give the names of the compounds but not the molecular formulas, for instance: "..a vigorous reaction takes place, and elemental molten barium and solid aluminum oxide are formed." Are we expected to know the formulas for compounds like aluminum oxide? or just common polyatomic ions?

Re: Test Question

Posted: Tue Oct 08, 2019 9:30 pm
by Chem_Mod
Formulas will typically be given on the test if they have never been mentioned before, and for simpler compounds, you should be able to figure them out. It is definitely useful to have the common polyatomic ions memorized.

Re: Test Question

Posted: Tue Oct 08, 2019 10:03 pm
by Kallista McCarty 1C
The only formula that you must know would be for a combustion reaction. They will give you one of the reactants but you should know it reacts with O2 to produce CO2 and H2O.

Re: Test Question

Posted: Tue Oct 08, 2019 10:13 pm
by Pegah Nasseri 1K
You should be able to write out the molecular formulas of common compounds like aluminum oxide or sodium chloride using the number of valence electrons each atom has. In an ionic compound, you can figure out how many valence electrons each element needs to fill their valence electron shell and balance the charges of each element to find the molecular formula. Having the polyatomic ions memorized will help you with writing some of the molecular formulas that contain them because you will have the charges of each one memorized.

Re: Test Question

Posted: Tue Oct 08, 2019 10:16 pm
by Leslie Magana 4C
You have to know the combustion reaction according to one of the TAs.

Re: Test Question

Posted: Wed Oct 09, 2019 12:01 am
by Patricia Chan 1C
You'll need to know combustion reaction reactants and products. Other than that, our TA mentioned that any other molecular formulas that may be more complex are usually given to you on the test. That being said, it might be a good idea to eventually memorize polyatomic ions and understand how to form molecular formulas.

Re: Test Question

Posted: Wed Oct 09, 2019 12:12 am
by Matt Sanruk 2H
Any numerical value/constants will be given to us, correct?

Re: Test Question

Posted: Sun Oct 20, 2019 5:17 pm
by Celena Kim 2I
Do we have to recognize charges of certain elements?

Re: Test Question

Posted: Sun Nov 03, 2019 10:36 pm
by Rosa Munoz 2E
Matt Sanruk 4F wrote:Any numerical value/constants will be given to us, correct?

The equation sheet we are given for the test is on the website.