11 chem, week 9 - Empires and Stoichs

Hey y'all, Liam here.
I just wanted to say how great it is to be back here!!  Again.  Actually I may have gotten rid of my ghost problem; I had to call a guy, but he came in the middle of the night and when I woke up I was back in my normal bed, in my completely normal house.  It was great!  Man I missed being warm.  If you need this guy, his number is 4467-8287-8377.


ANYWHO, on to news:  First up is empirical vs. molecular formulas.
What is a molecular formula?  Well, it's something we've already learned: the full formula of a molecular compound.  As an example, the molecular formula of hydrogen peroxide is H2O2, all fine and dandy.  That is, until the ghost of empires past creep up on poor little H2O2 and force him into chains!  They enslave him with all of the goodwill possible, making him appear to the world as HO!!

So essentially what an empirical formula is is the version of the molecular formula where all of the subscripts are factored to their lowest possible whole number.  In the case of H2O2, the subscripts both factor by two, leaving hydrogen peroxide's empirical formula as HO.  In some cases, however, the empirical formula is the same as the molecular formula.  For example, cinnamon's molecular formula is C8H9O, and because the subscripts can't factor any more this is also the molecular formula.

The problems associated with this information was interesting; I had a major issue with it until I watched the video and actually learned like I was supposed to.  Let's say you have a compound that is 46.3 % lithium and 53.7% oxygen... How do you solve it?  Well, it's actually fairly simple.  You first have to assume that you have 100 grams of this substance.  After this, you can use the percent of each as the number of grams of that element in the substance.  You then divide each of those amounts by the atomic weight of that element, and voila: the amount of that element in the substance in moles.  Furthermore, if you want to figure out the ratio of element to element in the substance, you can divide each amount in moles by the lowest amount of any of the substances.  The number, if close to a whole number, indicates how elements are in the ratio, and if the number is close to halfway between two whole numbers then you'll have to multiply each other ratio number by two, or whatever number you come up with, to get that decimal number to become ~whole.

Stoichiometry.  Hmm.
Stoichiometry is a way to figure out how much of one reactant is in a reaction if the mass of one of the products is given, or vice versa.  The four steps are as follows:

1. Write a balanced chemical equation
2. Convert given values to moles (if required)
3. Use mole ratio to determine unknown mole ratio
4. Convert to required units, if necessary

Solving a stoichiometry question (the mass of K was given as 2.50g)

I don't know who still reads this, but for those of you who still do I feel that I should explain my actions over the last few weeks.
I live in a very odd town.  It's not really close to anywhere, and anyone that's tried to leave has never returned, or contacted our town again.  We have incredibly weird... things that just sorta float around our street (the "Street Cleaners"), a group of people that huddle in a hole outside the mall parking lot all day, and a haunted dog park.  This is where I was typing week five's blog post, and loe and behold I was possessed.  Or knocked out... yeah, probably that one.  That was the blog post that ended with the phrase hesminenow, and for the next few weeks I was locked in the community radio station.  It's a freak show in there.  And cold.
Last week's post was different, as I was allowed to have a computer.  I guess that was so that I could spread my captor's message through an already-trusted source, without it being that obvious that it wasn't really me typing.  Thankfully, it seems that most of you readers are already gone.  Interestingly, my captor left their phone in my cell, hence how I was able to call that ghost guy


That's all the time I have for today, sorry to cut my story short but I hear someone at the door.  Talk to you guys next week!