Chemistry question - heat of reaction problem...

[tris-]

thanks for the inputs so far swords.

i would like to see what more orm has to say as he got the same answers as me.

thats if he wants to say anymore, lol.

 

[swords]

You are both doing:

Concentration = Moles / Volume *1000

its not *1000.

Make sure you are always working in the same units (g - L or mg - ml)

10ml = 0.01 L

DM-3 is = L
Mol/Dm-3 is the same as Mol/L so working in L you will always get the molarity in Mol/L which is Mol/Dm-3 do you see?

 

[tris-]

ye, so if u do 2.3mol / 0.010 l or dm3, see what you get?

230 mol dm-3

lol.

what kind of bitch ass acid is this

 

[swords]

2.3 moles per litre acid... how many moles in 10ml? i can guarentee you it's not going to be 230moles. (because there would be 23000 moles per litre then)

84 g/DM-3 is the concentration. (84 g/L)
so the number of moles value of 2.3 is for a 1L solution.

 

[tris-]

the question is how many mols in a litre.

i did think firstly it should be dividing the 2.3 by 1000 for some reason, because the number just seems right.

when i look at other answers to a similar question the conc is 0.0023 mol dm-3.

but both things are the same mols as its a 1:1 reaction.

but it cant have the came conc, because the amount of HCl needed to shit on NaOH was less than the amountof NaOH that is there.

so HCl is smaller but is taking bigger turds the same size as NaOH, so surely its conc will be higher? even though its mols are the same. so NaOH and HCl are the same size, but HCl turds are bigger than NaOH. so NaOH shits on HCl 4 times but HCl shits on NaOH just onces to make it stop.

i dont know, i been doin it for 9 freakin hours

 

[Ormorof]

its 84g dm-3 so thats 2.304 moles per litre, that would be the concentration then (2.304 moldm-3)

so in 10mL you would have moles = conc/1000 * volume

so,

2.304/1000 * 10 = 0.02304 moles in 10mL? so yeah i think swords is right, just putting it in a different way

i just got myself confused (interchanging concentration for the moles in the first equation, as it does state g dm-3, so thats 84g in 1 litre, or 2.304 moles in one litre )

so moles of NaOH = 0.02304 concentration (mol dm-3) can then be worked out by doing moles/volume * 1000

ie 0.02304/40 * 1000 = 0.576 mol dm-3

so to find the mass of NaOH in one litre do 0.576*39.99711 = 23g dm-3 then to find it in 40cm3 divide it by 1000 then multiply by 40 = 0.921g of NaOH present in 40mL (or so )

 

[Ormorof]

nerf edit time limit :O

just realised i did too much calculating... can of course just take the moles of NaOH and multiply by mass to get 0.921g in 40mL of solution (at 0.576mol dm-3 )

 

[swords]

I do it the special way...the one that takes the least pissing about

 

[swords]

the question is how many mols in a litre.

i did think firstly it should be dividing the 2.3 by 1000 for some reason, because the number just seems right.

when i look at other answers to a similar question the conc is 0.0023 mol dm-3.

but both things are the same mols as its a 1:1 reaction.

but it cant have the came conc, because the amount of HCl needed to shit on NaOH was less than the amountof NaOH that is there.

so HCl is smaller but is taking bigger turds the same size as NaOH, so surely its conc will be higher? even though its mols are the same. so NaOH and HCl are the same size, but HCl turds are bigger than NaOH. so NaOH shits on HCl 4 times but HCl shits on NaOH just onces to make it stop.

i dont know, i been doin it for 9 freakin hours

http://en.wikipedia.org/wiki/Mole_(unit)

Working in Moles can be confusing, but once you understand what a mole is an how it relates to other units you can more easily manipulate it.

Hope this helps.

 

[Haggus]

I don't get this, "It just is" shit. My teacher used to tell me it was just it otherwise nothing would exsist. Well I want to know why.. WHY WHY !

Why is it that way ?

Why is it like that ?

Why work it out like that and why must that equal that ?

Can't think of an example but i'm sure you know what I mean.

There are some like Ohm's law. V/IxR etc. That makes sence to be like that because otherwise it wouldn't work out.

But why do Moles = what ever it was in my last post

 

[Dandare]

I'm impressed ok who wants a job

 

[swords]

I don't get this, "It just is" shit. My teacher used to tell me it was just it otherwise nothing would exsist. Well I want to know why.. WHY WHY !

Why is it that way ?

Why is it like that ?

Why work it out like that and why must that equal that ?

Can't think of an example but i'm sure you know what I mean.

There are some like Ohm's law. V/IxR etc. That makes sence to be like that because otherwise it wouldn't work out.

But why do Moles = what ever it was in my last post

Look it up in the link i gave, explains what a mole actually is and how it is related to mass and molecular weight.

 

[tris-]

all i know about a mol is it is the mass of an element etc that contains 6.022 E23 particles/atoms/something.

tbh, thats all i want to know on what a mol is. thanks for the link though, if i go any higher i will take a look.

 

[Ormorof]

I don't get this, "It just is" shit. My teacher used to tell me it was just it otherwise nothing would exsist. Well I want to know why.. WHY WHY !

Why is it that way ?

Why is it like that ?

Why work it out like that and why must that equal that ?

Can't think of an example but i'm sure you know what I mean.

There are some like Ohm's law. V/IxR etc. That makes sence to be like that because otherwise it wouldn't work out.

But why do Moles = what ever it was in my last post

because they worked it out experimentally using The Scientific Method!!

 

[Lamp]

Try these 3 questions:

(1) Provide an equation representing the Schlenk equilibrium observed for Grignard reagents.

(2) True or False: Umpolung synthons are natural synthons ?

(3) Describe three synthetic routes to dialkyl magnesium compounds and the reasons for their success.

 

[noblok]

I don't get this, "It just is" shit. My teacher used to tell me it was just it otherwise nothing would exsist. Well I want to know why.. WHY WHY !

Those are the questions answered in religion and philosophy. Science says that a law is, but not why it is. The only way to answer such a question is a priori.

Why do things fall? Because of gravity. Why is there gravity? Because ... etc. Eventually the last question will be "Why is there something rather than nothing?" The only reasonable answer to this question is the one Parmenides already gave: the absolute nothing cannot exist, by defenition. "The being is and the not-being is not."

You cannot create something out of nothing. You can only conclude that there's always been something and will continue to be something forever. This goes for religion (in the god kind of way) as well: everything is created by a god, where did he come from? You can only say that he's always existed.

Sorry for going a bit off-topic. I'm afraid I can't help you with the chemical stuff .

 

[Lamp]

Those are the questions answered in religion and philosophy. Science says that a law is, but not why it is. The only way to answer such a question is a priori.

Why do things fall? Because of gravity. Why is there gravity? Because ... etc. Eventually the last question will be "Why is there something rather than nothing?" The only reasonable answer to this question is the one Parmenides already gave: the absolute nothing cannot exist, by defenition. "The being is and the not-being is not."

You cannot create something out of nothing. You can only conclude that there's always been something and will continue to be something forever. This goes for religion (in the god kind of way) as well: everything is created by a god, where did he come from? You can only say that he's always existed.

Sorry for going a bit off-topic. I'm afraid I can't help you with the chemical stuff .

Not necessarily true. Man defines boundaries and limits around him to explain and give comfort. Man is transient. Mortal. Why can't absolute nothingness exist ? I can't prove it of course - so it comes down to my personal belief. My personal belief is that big bangs (there are trillions of them) explode into a void - a "space" of absolute nothingness. In our universe it is beyond our comprehension to explain how and why the big bang occured. Again, and its my personal belief, I believe that there exists physical laws that we cannot and probably never will know or understand. One of these is that there is a phenomenon where matter CAN be created out of nothing. I can't explain it. But I don't believe that "God" created everything.

I love this stuff btw ))

 

[Lamp]

Forgot to mention something. Sorry.

Black hole singularities. That "bit" of the black hole where matter and light is compressed to infinite density. Try for a moment to imagine how trillions of billions of tonnes of matter can be compressed into something the size of an sub-atomic particle of an unimaginable density. And there's one of those in the middle of every galaxy. Super black holes.

Scientists are waiting to "crack" the theory of quantum gravity which they reckon can help explain how our universe works.

Fascinating.

 

[noblok]

Bleh, this is kind of hard to explain, but I'll give it a shot. You can not think the absolute nothing, because a tought is something and thus can't grasp the absolute nothing. If you attempt to think the absolute nothing, you think of something. Namely the nothing, but since this nothing is something (the subject of your toughts) it cannot be an absolute nothing.

The not-being can not exist by definition, because something that exists, is. Either something exists or it does not exist. This world exists or it doesn't, it cannot exist a bit. This doesn't exclude a relative nothing though, a nothing as in the absence of something. I don't think an absolute nothing can exist though, again, by defenition.

On the "nothing comes from nothing": how would you explain that something comes from nothing? If there is nothing, then surely nothing can appear all of a sudden, where would it come from? Same goes the other way around; something can't just become nothing, where would it go? Into a void, but then there still is a void and how can the void be nothing when it has all these things in it?

I must admit that I'm not much of a scientist, something which I regret. Quantumphysics and the like seem immensly interesting, might be something for later .

 

[swords]

Try these 3 questions:

(1) Provide an equation representing the Schlenk equilibrium observed for Grignard reagents.

(2) True or False: Umpolung synthons are natural synthons ?

(3) Describe three synthetic routes to dialkyl magnesium compounds and the reasons for their success.

*********************************************************

No ta
Biochemist, i make proteins and such, not tis dialkyl blah blah pure chemistry lark!

Though i do have a grounding in PEGylation of a phosphine activated thiol...

 

[Ormorof]

Try these 3 questions:

(1) Provide an equation representing the Schlenk equilibrium observed for Grignard reagents.

http://www.chem.ox.ac.uk/ectoc-3/grignard.html

cant be arsed to copy it out

btw, for anyone who cares i passed my first semester of uni with a first yay

 

[Tasslehoff]

Bleh, this is kind of hard to explain, but I'll give it a shot. You can not think the absolute nothing, because a tought is something and thus can't grasp the absolute nothing. If you attempt to think the absolute nothing, you think of something. Namely the nothing, but since this nothing is something (the subject of your toughts) it cannot be an absolute nothing.

The not-being can not exist by definition, because something that exists, is. Either something exists or it does not exist. This world exists or it doesn't, it cannot exist a bit. This doesn't exclude a relative nothing though, a nothing as in the absence of something. I don't think an absolute nothing can exist though, again, by defenition.

On the "nothing comes from nothing": how would you explain that something comes from nothing? If there is nothing, then surely nothing can appear all of a sudden, where would it come from? Same goes the other way around; something can't just become nothing, where would it go? Into a void, but then there still is a void and how can the void be nothing when it has all these things in it?

I must admit that I'm not much of a scientist, something which I regret. Quantumphysics and the like seem immensly interesting, might be something for later .

That's a whole lot of words for saying nothing doesen't exist, which actually is a moot point, as nothing is something defined by men. In my opinion!

And if I we can argue whether or not "nothing" is defined by men, it is, as it would be too clearly defined if not.

 

[Lamp]

The thing about alternative universes, and alien physical laws, is this:

We can't PROVE they don't exist. Therefore they MIGHT exist.

Its where belief meets science fiction.

 

[Lamp]

That's a whole lot of words for saying nothing doesen't exist, which actually is a moot point, as nothing is something defined by men. In my opinion!

And if I we can argue whether or not "nothing" is defined by men, it is, as it would be too clearly defined if not.

Totally agree, but for different reasons. Another example.

We don't know for sure that there are other intelligent beings in our universe. But we believe there might be.

 

[noblok]

They might exist, but that doesn't exclude that either they do or don't exist, does it? The 'might' only expresses an uncertainty in this case: we don't know if they exist, but this doesn't mean that they exist only a bit.

Tasslehoff: yeah, it's a lot of words, but I didn't know how to make my point clear in fewer words. At least i hope all the extra information made it clearer and not more complicated .

/edit: edited because my first interpretation of "might" wasn't adequate .

 

[Ormorof]

The thing about alternative universes, and alien physical laws, is this:

We can't PROVE they don't exist. Therefore they MIGHT exist.

Its where belief meets science fiction.

hehe its like the ol' cat in the box principle.... you put a cat in an air tight sealed box, until you open the box again you dont know if its alive, or dead... so theoretically it could be either at the same time

 

[noblok]

hehe its like the ol' cat in the box principle.... you put a cat in an air tight sealed box, until you open the box again you dont know if its alive, or dead... so theoretically it could be either at the same time

It can't be either at the same time. Dead and alive are mutually exclusive, considering the definition of dead ("having lost life; no longer alive").

 

[tris-]

i think he means the whole point is you dont know.

meaning you can only speculate is it dead, is it alive? i think its alive, how do i know? i think its dead, how do i know?

 

[noblok]

My reaction was aimed at the "so theoretically it could be either at the same time" . The fact that you cannot know whether it's alive or dead is an different matter altogether. Then again, can you ever know something 100% sure? "Cogito ergo sum", but you won't get much further if you want 100% certainty.

 

[Haggus]

Yes but I'm not willing to accept that

Arg it's hard to explain how I feel towards it.

I don't accept the fact that there HAS to be something there, maybe the only reason it was created because if it wasn't. The world would implode and kill us all or something.

Doesn't the law state that you need proof, hard evidence for something like this ? Like in a caught case, someone says "I didn't do it" and has no proof, or someone who says "Yes I was with my mother at the time, fo cos i'm not guilty kkthxbye". You would belive the one wit hthe proof. This is the basic princeables no ?

Saying gravity exsists because something falls on the floor when you drop it is annoying to me. Because it's just made up. No proof. Nothing. Someone said "oh, i'll call that gravity and I i'll test to see the terminal velocity which is 9.27m/s (or something close to that)

HOW to prove there is a force pulling that object towards the centre of the earth ? If you dug a hole through the earth and it went to one side to the other and you drop'd something down it. Would it fall out the other end or would it just float in the middle? (Theroticly this wouldn't be possible with the heat of the core of the earth. But take them out of the equasion just for this)

I hate physics, for this reason. I dissagree on everything and am not willing to accept it (Also my teacher was sexist and gave me a hard time but thats nothing to do with the subject, but y'all got me in the talky talky mood so I can't shut up. Bastids !)
I think aliens came down and told us we must have a name for something even if it doesn't exsist or we'll push the red button and you go big badda boom bye bye wankers. Joking about this bit.