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Chem Help

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Chem Help

Unread postAuthor: MrCrowley » Tue Nov 13, 2007 8:27 pm

Well I got my NCEA exams coming up next week, NCEA is our national exam thingy that seniors sit.
Anyway I pretty much flunked Chem this year, not paying much attention but somehow scraping through the topic tests only just.

For revision im doing exams from previous years, but you kind of have to know how to do the questions first.

So does anyone know a really good chemistry site that could be used for revision?

I was in Europe when we did these equations and have no clue what they're called or how to do them, so I need help, bad.

QUESTION SEVEN

Copper (II) oxide is reduced by excess hydrogen:

CuO (s) + H2 (g) → Cu (s) + H2O ()

Calculate the mass of copper (II) oxide that will be needed to give 18.0 g of copper




Mass copper (II) oxide =




Thanks.
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Unread postAuthor: Zen/// » Tue Nov 13, 2007 8:35 pm

Whoa, Im in Grade 8. (im 13) and after reading your post, Im not looking forward to university anymore...

Frankly I have no idea :D
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Unread postAuthor: mopherman » Tue Nov 13, 2007 8:38 pm

Zen/// wrote:Whoa, Im in Grade 8. (im 13) and after reading your post, Im not looking forward to university anymore...

Frankly I have no idea :D


I too am just out of my 8th grade chem course. (dont laugh) That looks like a chemical equasion to me. the idea is to screw with it by adding exponents so the two side ballance out. Then I'm pretty sure the patthats left over would be X. but then again, I'm probly worse than you when it comes to seior evle chem....
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searching for a modern day savior from another place,inclined toward charity,everyone's begging for an answer,without regard to validity,the searching never ends,it goes on and on for eternity
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Unread postAuthor: MrCrowley » Tue Nov 13, 2007 8:40 pm

This isn't Uni, it's Level 1 Chemistry.

In America you may be able to start Chem earlier but here you can only learn it as a single subject in 5th Form - 7th Form(11th-13th Grade I think)

So yeah my first year of chem was tough, hence i'm not doing it next year.

These equations aren't too bad, I just forget what you devide what by, since I listen to music and not the teacher mostly :roll:
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Last edited by MrCrowley on Tue Nov 13, 2007 8:54 pm, edited 1 time in total.
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Unread postAuthor: Zen/// » Tue Nov 13, 2007 8:41 pm

I live in canada, around the 3rd smartest nation in teh world.
^^^^Japan is first I think...
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Unread postAuthor: jackssmirkingrevenge » Tue Nov 13, 2007 8:43 pm

It's something to do with molecular mass, fucked if I know tho - I might work in a lab but i haven't touched this sort of chemistry in 10 years :roll:
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Unread postAuthor: mopherman » Tue Nov 13, 2007 8:43 pm

MrCrowley wrote:This isn't Uni, it's Level 1 Chemistry.

In America you may be able to start Chem earlier but here you can only learn it as a single subject in 5th Form - 7th Form(11th-13th Grade I think)

So yeah my first year of chem was tough, hence i'm not doing it next year.

These equations are too bad, I just forget what you devide what by, since I listen to music and not the teacher mostly :roll:

Dude dont give up chem. It's practically the most valuable skill a spudder can have. But yeah, Its cool that we get to start early over here. :)
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Unread postAuthor: Zen/// » Tue Nov 13, 2007 8:45 pm

My subjects are science, math, gym, social studies, health, english, french, option (band :evil: , drama :) , and art :o )

I go to a french immersion school, everything but health and english are in french....

Edit: YAY! Here are the top ten nations with percentage of population (35-64) with a four year degreed.

10. Switzerland - 26%

9. Norway - 28%

8. Australia - 28%

7. New Zealand - 29%

6. Denmark - 31%

5. Sweden - 31%

4. Japan - 31%

3. Finland - 31%

2. United States 39%

1. Canada - 41%
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Last edited by Zen/// on Tue Nov 13, 2007 8:51 pm, edited 1 time in total.
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Unread postAuthor: mark.f » Tue Nov 13, 2007 8:49 pm

Stoichiometry, yay!

You need one mole of copper oxide to yield one mole of copper.

Converting that to grams, you get that you need 79.55 grams of copper oxide to yield 63.55 grams of copper metal.

Using a simple proportion:

<table><tr><td><pre>
79.55 n
----- = --
63.55 18

1431.9 = 63.55n
n = 22.53
</pre></td></tr></table>

You get that you need about 22.53 grams of copper oxide.

And Mopherman, this type of chemistry is more useful in other deviant fields... more so than spudding. :twisted:

EDIT - Sorry, it just occurred to me that they might ask you to show your work. Therefore, you'd have to show the dimensional analysis instead of taking the shortcut I did. In that case, here's the D.A., (the proper way to solve a stoichiometry problem):

<table><tr><td><pre>
18g Cu 1 mol Cu 1 mol CuO 79.55g CuO 1431.9g CuO
------ * --------- * --------- * ---------- = ----------- = 22.53g CuO
1 63.55g Cu 1 mol Cu 1 mol cuO 63.55
</pre></td></tr></table>
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Unread postAuthor: MrCrowley » Tue Nov 13, 2007 9:30 pm

Don't worry I managed to figure it out fiddling round with some numbers :P

I just devided 1431.9 by 18 and got 79.55, then figured the rest out from that.

Thanks for the help.
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Unread postAuthor: Hubb » Tue Nov 13, 2007 9:40 pm

You asked about a site to go to?

Wolfram Science

It has other features as well, including mathematics and physics.
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Unread postAuthor: MrCrowley » Tue Nov 13, 2007 9:53 pm

Sweet, I got some program called CHEMIX or something, but it's a [female doggy] to figure out how to work the damn thing.
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Unread postAuthor: Hubb » Tue Nov 13, 2007 9:58 pm

I feel you. I tried to use Chemix but was unsuccessful as well.
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Unread postAuthor: shud_b_rite » Tue Nov 13, 2007 10:31 pm

I got exams coming up too. Look up crocodile chemistry. Its a thing we used at our school and its pretty much like "mix anything together and see what happens" it also has lessons and tutorials on it too.
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Unread postAuthor: sandman » Tue Nov 13, 2007 10:37 pm

lol, i thought u were better at chem than i McCrowley, and im in AP Chem. Well u sure threw me, but u got the answer none the less :wink:
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