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Questions (42)
(delta)Eg = -14.7J
Therefore, Ek = -(delta)Eg = 14.7J I don't understand how you'd come to the above conclusion? Does Ek just
1 answer
405 views
Reviewing for exams and completely forgot how to do this and looking back at my notes doesn't help for this one... Can you
2 answers
523 views
How would you be able to recognise that C5H8 was an alkyne?
And how would you know that CH3COCH3 was a ketone? (I thought it was
1 answer
433 views
Apoarently the name of this compound is 4-ethyl-4-methylheptane:
........................CH3 ..........................|
1 answer
544 views
I understood this at one point and now I'm confused again! :(
What's the difference between 2,2-dimethyl and 2-ethyl? It's hard
1 answer
537 views
................CH3
..................| CH3-CH2-N-CH2-CH2-CH3 Hoping this turns out okay, but it's an amine and branching off of
4 answers
812 views
I'm having a lot of trouble with Naming organic compounds when given things like HCOOCH2CH2CH3.
Can you recommend some steps? How
3 answers
507 views
How do you draw N,N-dimethylheptanamine?
The N,N part is confusing me most.
2 answers
382 views
Name each compound.
/\/\NH2 (that's suppose to be a line diagram...) I got 1-pentanamine, but that's wrong. CH3CH2-O-CHCH2CH3
3 answers
400 views
Explain why iron corrodes more quickly in seawater than in freshwater.
I'm getting conflicting answers from searching on Google;
1 answer
1,279 views
20.00mL of a 1.100E-4 mol/L Pb(NO3)2 is mixed with 80.00mL of 4.450E-2 mol/L CaI2. Will a precipitate form?
Here's what I did...
2 answers
485 views
I need help starting this question...
A buffer solution is prepared by adding 30.0g of pure acetic acid to 41.0g of sodium
1 answer
764 views
Okay, I feel like this question should be really easy because it's a multiple choice question but how do you figure it out?? I'm
1 answer
475 views
I'm reviewing for a test and I'm on Le Chatelier's principle. Decreasing the temperature of an exothermic reaction shifts the
1 answer
1,016 views
The Ksp for nickel(II) hydroxide is 5.47E-16. What is the base dissociation constant for nickel(II) hydroxide?
So I started off
2 answers
2,716 views
I need help starting this question:
A buffer solution is prepared by adding 30.0g of pure acetic acid to 41.0g of sodium acetate
0 answers
603 views
I'm trying do this question:
0.10 mol/L hydrochloric acid is titrated with 0.10 mol/L methylamine, CH3NH2. Calculate the pH of
0 answers
731 views
Ca(OH)2, CaF2, NH4NO3, KNO3, HNO3 - Arrange the solutions from most basic to most acidic.
I know Ca(OH)2 will be most basic and
2 answers
1,017 views
Sodium methanoate, NaHCOO, and methanoic acid, HCOOH, can be used to make a buffer solution. Explain how this combination
2 answers
6,755 views
In the equation Q = mc(deltaT), I learned that Q means heat transfer. Is it the heat transfer from the system to the
2 answers
885 views
Factors affecting reaction rate.
Use collision theory to explain. Factor: nature of the reactant Affect on rate: more or less
1 answer
696 views
50 mL of copper(II) sulfate reacts with 50 mL of sodium hydroxide. Their concentrations are 0.3 M and 0.6 M respectively. The
1 answer
1,000 views
Can someone check my answers please?
I had specific trouble with 7, 13, and 27 (I'm pretty sure my other answers are correct;
0 answers
740 views
for an assignment I'm writing, I'm trying to find the % efficiency of ethanol.
We were given a chart that says ethanol's energy
0 answers
518 views
There's something wrong with this sentence but I can't put my finger on it!!
The federal government has put into effect a mandate
4 answers
414 views
I'm having trouble with motion graphs.
How do you go from an acceleration-time graph to a velocity-time graph or displacement
0 answers
676 views
A horse runs 15 m [N 23° E] and then 32 m [S 35° E]. What is the total displacement of the horse?
I can't even visualise
1 answer
5,142 views
Mg + 2HCl -> MgCl2 + H2
Over an interval of 1.00s, the mass of Mg changes by -0.011g What is the corresponding rate of
1 answer
753 views
This is a chemistry lab report, but I was wondering if someone could edit the grammar and look at the sentence structure, etc.
I
4 answers
1,893 views
I had a quiz today and one of the multiple choice questions was something like, "find the final temperature of aluminum when it
3 answers
584 views
You know how when you do calculations for the enhaloy change of a reaction you start sort of like this?:
NH3(aq) + HCl(aq) →
4 answers
569 views
Can you check my calculations, please? It's for a lab we did in order to find the the enthalpy of formation of NH4Cl(s). My
3 answers
2,802 views
Hi, here's my (almost) 2-paged lab report introduction (hopefully you remember it from yesterday).
I went to class today, and
3 answers
947 views
Firstly, is this right?:
Exothermic reactions have a negative enthalpy change value because the enthalpy of the reactants are
1 answer
666 views
I wrote an introduction for a lab report for the first time, and I was given no samples (my teacher said "feel free to ask your
2 answers
473 views
Why wouldn't you do this reaction directly in a lab (and would rather use Hess' Law to determine the enthalpy of formation)?:
1/2
1 answer
1,348 views
Why is the enthalpy of the reactants greater than the enthalpy of the products in an exothermic reaction?
If it has something to
2 answers
1,309 views
I'm trying to write a sentence like this:
Exothermic reactions have a negative enthalpy change value because the enthalpy of the
1 answer
486 views
Is this right?:
Energy is absorbed in order to break bonds because bond breaking requires energy. Or are these two statements
7 answers
1,390 views
Had a recent mix-up when I re-read my chemistry notes, and trying to clear things up properly; is this right?:
When bonds form,
1 answer
587 views
"Describe the characteristics of each graph (for example, . . . ., zero or non-zero intercept value)."
I guess a zero intercept
1 answer
694 views
I did a lab today in class and part of the lab is to experimentally find the enthalpy for the dissolution of ammonium chloride
4 answers
1,212 views
Answers (32)
Sorry, I keep thinking of more stuff... Complications always magically arise right before an evaluation and never while I can actually ask my teacher :( Can there be more than three in a branch? So far we've only done ones with methyl, ethyl, and propyl,
Also, if there's branches coming off of it, what do you do? For example, if the left part had a branch: CH3 ...| CH3-CH2-N Or would that just be extending the branch? And it would make the "N-ethyl" into "N-propyl"?
And how would you know if there's double bonds?
No, sorry, it'd be an ester right?
And how would you know something was a cyclic hydrocarbon when given something like CH3CH2COOH? (I know that one isn't a cyclic hydrocarbon but I mean like when you get questions saying "name the organic compound" and they give stuff like CH3CH2COOH and
..........CH3...................................CH3 ............|..........................................| CH3 -- C -- C =(triple bond)= C -- C -- CH3 ............|..........................................|
I forgot to write ^2 on the [I-] for Qsp. Just a typo though, I did square it when I punched it in my calculator.
Oh, are the other three salts? And you just have to see whether they're acidic or basic or neutral salts? I got that KNO3 was neutral, CaF2 was basic and NH4NO3 was acidic? So.. Ca(OH)2, CaF2, KNO3, NH4NO3, HNO3? Is there another way I should be doing this
Oh okay so they have two distinct jobs, but they're still together in the solution? For example in a lab or something, both chemicals would be mixed inside one beaker? Is this explanation right?: If an acid is added, the H3O+ ions will be removed by
The example problem I gave is the root of all my confusion... Before, I always though when you do Q=mc(deltaT), you're getting the amount of heat absorbed/released by the SURROUNDINGS, and so when you want to get deltaH, you'd have to make Q negative in
and if another "that" was added then "to" would change to "must", I guess?
Maybe another "that" after "requires"?? The "...that ____ that..." bothers me though. Too many 'that's!
If it is feedback on only a small portion of it which could be read quickly, then thank you, but it did not come off that way.
(which is why I put it under English this time, rather than chemistry)
I don't mean to sound rude, but you couldn't have read that all in less than a minute and so you couldn't have truly come to that conclusion. Please don't give false feedback.
I actually already got one to read it and he said, "I see nothing 'wrong'." so I guess nothing "wrong" with quotes would mean there are some technical issues or something, I don't know. but this time around I was loOking more for a grammar check, but I can
That's alright, thanks though.
Hi Writeacher, I was wondering if you could take a look at my question jiskha(dot)com/display.cgi?id=1361488610 I don't know if you already have and decided not to answer it (never mind if you already did look at it), it's just that I've seen you edit some
Thanks; I obviously got it wrong, but what was my teacher talking about when she said that when you have a solid reacting, you don't use the mass of the solid for Q=mc(deltaT), only the mass of liquids or solutions? Why wouldn't that apply in this case?
That's what I don't really understand. If it's of the total reaction, shouldn't you add, in my example, the moles of both reactants? i.e. 0.025 +0.025 = 0.05 mol. Then use that value when doing deltaH = -Q/n? How come you only use The moles of one?
So if you find the enthalpy change for one reactant, it's the enthalpy change for the other reactant (and products??), i.e. you know the enthalpy change for the entire reaction? So enthalpy change of one reactant (or product also?) = enthalpy change of
Oh, oops ! I forgot to put x100 and then the rest of my answer, 4.8% (or 5%) I think it's a small miracle that I didn't make any mistakes when calculating the enthalpy of formation, there were a ton of steps! Thank you so much!
Oh no! :( I tried to sum up the stuff as best as I could and be brief since I felt that two pages was way too long, but now I feel like I shouldn't have done that... I'll ask her tomorrow how much detail she expects, etc. because I don't really think mine
I thought it might be kind of obnoxious of me to just post two pages worth of stuff and ask someone to read it, but thank you so much for being willing to look at it, I'll definitely repost tomorrow! Thanks for answering, and good night!
But that would happen AFTER a reaction... Why would a reaction end up being expthermic if, originally, the enthalpy of the reactants are greater than the enthalpy of the products. And also, why do weaker bonds have more enthalpy/energy?
I'm basically trying to explain why, in exothermic reactions, enthalpy of the products are greater than the enthalpy of the reactants (resulting in a negative enthalpy change). And I obviously don't know myself. Can someone please explain? I can't seem to
It's just that I have to include both ideas together in a paragraph and I writing, "Energy is required to break a bond. Breaking a bond requires energy." doesn't have "flow" and would work better in one sentence.
Basically, ignore the rest of my question if the above sentence is okay.
Sorry, I think this sentence should be alright, "Energy is required to break bonds, and when the bonds break, energy is absorbed." Don't know why I had to go through all that trouble to reach this simple sentence, but...
This question came up because I'm trying to write for the introduction in my lab report, "Energy is required to break bonds, so when bonds break, energy is absorbed". But that sounded off (because that's like saying the absorption of energy when bonds
i.e. is energy absorption a result of breaking bonds, or is energy absorbed in order to break bonds? So like... Energy is required to break bonds. Energy is somehow obtained, the bonds break... and this results in the absorption of *different* energy
So for the neutralisation one I'm way off, right? Is it unacceptably off? Because my teacher said we'd have tomorrow to continue if we didn't finish, so I might just do that part again. That makes more sense, thanks so much for answering (for all the other
