Chemistry: Post your doubts here!

[Mahmood Magdy]

Guys I need your help! How do I prepare a solution of sodium nitrate at 25 mmol dm–3 knowing that the molar mass of sodium nitrate is 85 g mol–1.
Thanks in advance

 

[Xylferion]

Guys I need your help! How do I prepare a solution of sodium nitrate at 25 mmol dm–3 knowing that the molar mass of sodium nitrate is 85 g mol–1.
Thanks in advance

Too little information right there. All you've mentioned is the concentration you want and the molar mass you have.

Concentration =[Mass / Molar Mass ] / Volume

You've only mentioned,

25 = [Mass / 85] / Volume

You're missing one more quantity.

 

[mohammed awadh]

With propane, there are 3 carbons. You can have the little dot ・, which is basically an electron, appear on any of the three carbons.

The thing is, if you have it on the first and third carbon, that's the same thing, because you will start numbering the carbons, from the one that has ・.

The only other carbon which you can have the ・ attached to, is the second one.

This gives you only two places to put ・.

During the termination step, you have two combine two radicals. That is two molecules that have ・.

Since ・ can be on the first OR the second carbon, you can form 3 combinations.

First carbon radical ・ + First Carbon radical ・
First carbon radical ・ + Second carbon radical ・
Second carbon radical ・ + Second carbon radical ・

So if you have C3H7・ as your radical. The ・ can be on the first or second carbons.

-C-C・-C-
OR
・C-C-C-

View attachment 52150

View attachment 52151

Thank you so much. so you are basically joining the free radicals right? if so , then does the radical dot give rise to the methyl group branched?

 

[Xylferion]

Thank you so much. so you are basically joining the free radicals right? if so , then does the radical dot give rise to the methyl group branched?

Nope, it's just that when they join, the radical dot continues its chain with the other radical. It all depends on how you connect the radicals together. Much like tetris.

 

[mohammed awadh]

Nope, it's just that when they join, the radical dot continues its chain with the other radical. It all depends on how you connect the radicals together. Much like tetris.

Man you are the best how do people get such brains haha very intrigued

 

[The Chill Master]

M/j/09/21

Q 4 (b) both part can someone please explain???????????

Q (5) (e) part what should be the reasoning???????
Like should we define why we name the compound cis and all other stuff or is it something else?????

Thanks in advance.

 

[qwertypoiu]

M/j/09/21

Q 4 (b) both part can someone please explain???????????

Q (5) (e) part what should be the reasoning???????
Like should we define why we name the compound cis and all other stuff or is it something else?????

Thanks in advance.

I have assumed you managed to find these compounds (ask if you didn't)
Compound C is CH2(OH)CH(OH)CO2H
Compound D is CH3CH2OH
Compound E is CH3CO2H
Note that C contains two alcohol groups (diol), and a carboxylic acid group.
D contains an alcohol group, and E a carboxylic acid group.
i) For C with D:
Since D is an alcohol, it MUST react with the acid group of C to form an ester:
CH2(OH)CH(OH)CO2CH2CH3
ii) For C with E:
Since E is an acid, it MUST react with the alcohol groupS of C to form a DIester:
CH2(O2CCH3)CH(O2CCH3)CO2H
(two E's react with one C)

Note that O2C is the ester group reversed. (CO2)

 

[The Chill Master]

I have assumed you managed to find these compounds (ask if you didn't)
Compound C is CH2(OH)CH(OH)CO2H
Compound D is CH3CH2OH
Compound E is CH3CO2H
Note that C contains two alcohol groups (diol), and a carboxylic acid group.
D contains an alcohol group, and E a carboxylic acid group.
i) For C with D:
Since D is an alcohol, it MUST react with the acid group of C to form an ester:
CH2(OH)CH(OH)CO2CH2CH3
ii) For C with E:
Since E is an acid, it MUST react with the alcohol groupS of C to form a DIester:
CH2(O2CCH3)CH(O2CCH3)CO2H
(two E's react with one C)

Note that O2C is the ester group reversed. (CO2)

Thank's a lot..........

 

[qwertypoiu]

M/j/09/21

Q 4 (b) both part can someone please explain???????????

Q (5) (e) part what should be the reasoning???????
Like should we define why we name the compound cis and all other stuff or is it something else?????

Thanks in advance.

Just saw your second question sorry missed it before.
For cis and trans answers, the explanation should be in terms of the methyl groups or hydrogen atoms being on the same or
opposite sides relative to the C=C bond. So you have to state the reason why you chose to call a compound cis or trans.

 

[Princess Raven]

W09 p42 can some please explain question 1 part b
And question 3c ii only the balancing part and question 8 d
Please

 

[The Chill Master]

Just saw your second question sorry missed it before.
For cis and trans answers, the explanation should be in terms of the methyl groups or hydrogen atoms being on the same or
opposite sides relative to the C=C bond. So you have to state the reason why you chose to call a compound cis or trans.

Oh.
Thanks for the help.

 

[MYLORD]

can anyone help me with this question

 

[Mahmood Magdy]

Too little information right there. All you've mentioned is the concentration you want and the molar mass you have.

Concentration =[Mass / Molar Mass ] / Volume

You've only mentioned,

25 = [Mass / 85] / Volume

You're missing one more quantity.

Oh yeah, sorry for that. But thanks for the equation though.

 

[MYLORD]

anyone ?

 

[Boss201]

Can someone tell me how to perform calculations using the mole concept , involving volume of gases(burning of hydrocarbons)

Thanks

 

[liptonice]

guys if I practice pastpapers open book only, can I get a* grade ? or whats the way to get that a* in 3 weeks ?

 

[liptonice]

guys paper 5 june 2014 - 51 question 1 a / ii /

how can i calculate the volume of nitrogen iv oxide and oxygen ?

 

[princess Anu]

can somebody explain this observation;
The bond energy of nitrogen nitrogen bond is 944 KJ/mol while the bond energy of carbon oxygen bond in CO molecule, which is isoelectronic with nitrogen, is 1074KJ/mol

 

[princess Anu]

Also,
What could be the bonding between C02 and H20 in fizzy drinks? is it Hydrogen bonding?

 

[liptonice]

Also,
What could be the bonding between C02 and H20 in fizzy drinks? is it Hydrogen bonding?

h bond