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Chemistry HL/SL help


Hedron123

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I got it thanks!

I also had another question...

How do I solve this?

Na(s) + 2H2O(l) ⇒ 2NaOH(aq) + H2(g)

# of moles: ? XS (=excess) ? ?

quantities (m or V at STP): 2.00 g ? ?

I know that 23/2=11.5 and that's the number of moles for Na but then I'm lost..

Also can anyone answer this question:

"How can you simply make elemental bromine, Br2, from the compound NaBr?

I don't understand how to just "know" the answer to these questions..

I thought about putting some chlorine in there to make NaCl but that would make a huge reaction right?

Thanks!"

Thanks so much for the help :)

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  • 3 months later...

Hail everyone!

I currently have Chemistry on standard level in 1DP, beneath my whole human science profile. As I want to become an economist, my forward experimental subject is Chemistry (It's like that one is the one that I partly understand :) ). Can anybody support me with views from the Matura exam? There are three papers not fully understood by me, but I want to somehow prepare to it.

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Hi,

I'm in the same situation as you and decided to take Chemistry HL instead after my teacher convinced me to take it.....I am taking Physics, Chem and Math HL so do you think it's going to be suicide??

These are some of the most difficult subjects the IB offers, but if you're interested in an engineering career (especially something chemical-based) then this is what you must do, and engineering school's only going to be harder. If you keep up with the courses, have a good work ethic, and have a decent amount of mathematical/scientific aptitude you should be okay.

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  • 2 weeks later...

Hi all,

Since this is a Chemistry HL/SL help discussion, I was hoping somebody would be able to answer this question for me:

Why does the secondary alcohol have a lower heat/enthalpy of combustion as opposed to a primary alcohol?

The textbook I've got never talks about the reasons why; it only tells me that as the carbon chain gets larger, the enthalpies of combustion should increase because you need to break more bonds. But secondary and primary alcohols aren't necessarily going to be of different carbon chain lengths- for example, 1-propanol and 2-propanol, but their enthalpies of combustion are still different.

Is it to do with the position of the function group (OH)? And if so, how does the position of the functional group affect the enthalpies of combustion?

Please help! (>_<)

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  • 3 weeks later...

Hi,

I've just started writing my lab report about molar enthalpy of reaction of neutralization (koh+h2so4) and I cannot find specific heat capacity of KOH solution anywhere :(.

Do you have any idea where I can look for it? I've tried NIST, Chemical Abstracts, International Critical Tables... And only specific heat capacity of KOH I've seen is for solid state :(.

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Hi,

I've just started writing my lab report about molar enthalpy of reaction of neutralization (koh+h2so4) and I cannot find specific heat capacity of KOH solution anywhere :(.

Do you have any idea where I can look for it? I've tried NIST, Chemical Abstracts, International Critical Tables... And only specific heat capacity of KOH I've seen is for solid state :(.

 

On page 1040 you will find a table of specific heat capacities for KOH. Use the one that corresponds to the temperature you ran your experiment at:

 

http://www.nist.gov/data/PDFfiles/jpcrd525.pdf

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Hi:) It's me again;/. I have another question considering the same lab report, where can I find enthalpy change of reaction of neutralization: 2KOH + H2S04 -> K2SO4 + 2H20?

Yes I've tried google, but I cannot find the proper value :(.

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Hi:) It's me again;/. I have another question considering the same lab report, where can I find enthalpy change of reaction of neutralization: 2KOH + H2S04 -> K2SO4 + 2H20?

Yes I've tried google, but I cannot find the proper value :(.

 

Not the most "proper" source but this page here: http://www.4science.org.uk/assets/files/pdf/aqa11-enthalpy.pdf gives the value at -57 kJ/mol per one mole of water. Since two moles of water form, -114 kJ/mol is the value you should use to determine your percent error. You can probably find a more reliable source, but this is better than nothing.

 

You should get better at using Google :P :P

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  • 2 weeks later...

Hey people, I've been away for a while. The good thing is that I'm back and I'm willing to help any Chemistry student with their problems or doubts. I'll be glad to help you with questions regarding lab reports, designs, theory or even on how to approach the actual paper.

I hope to be useful.

Thanks in advance.

Regards

Hi so im new here

anyway im heading into my second year of ib and im taking chemistry at hl my one wish is to get a 7 or at least a 6 I always get 4's. I study extremely hard and I know that's not my problem

so I was wondering if you can give me some advice.

thank you!

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Hi! Is this post still worth writing on? Well, I extremely need help in Chem! I'm in 12th now but 11th went BAD! Unexpected actually.  Always in Paper 2, the first question is on some lab related question. I need someone to make a list of topics that are likely to show up on these questions...i know of titration, concentration, and what else? 

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Hi! Is this post still worth writing on? Well, I extremely need help in Chem! I'm in 12th now but 11th went BAD! Unexpected actually.  Always in Paper 2, the first question is on some lab related question. I need someone to make a list of topics that are likely to show up on these questions...i know of titration, concentration, and what else? 

 

The syllabus tells you everything that can be asked. Usually it's one data-based question, one organic question, one acid-base question, one redox question, and then the rest is up to the IB.

 

Go study the syllabus.

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General question:

My results for SL chemistry are never what I would love them to be, and I was wondering what is the best way to study for chemistry?

 

Understand every point on the syllabus (they will not ask anything that's not on it), and then do as many past papers as you can.

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  • 2 weeks later...

Hey people, I've been away for a while. The good thing is that I'm back and I'm willing to help any Chemistry student with their problems or doubts. I'll be glad to help you with questions regarding lab reports, designs, theory or even on how to approach the actual paper.

I hope to be useful.

Thanks in advance.

Regards

 

Hello! I was wondering if someone could help me think of an idea or topic for my Chemistry SL monograph. It would be excellent if I could do the experimental part of this project. I would be really really thankful if you could help me with this.

 

Thanks for your attention 

 

PS: I would also appreciate if anyone has any advice about doing my monograph. 

Edited by vero97c
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