stonecold's chem questions :)

[stonecold]

but i thought you can't attach to the first and last carbons, because then all you are really doing is making the chain longer...

[simonhu81292]

hey stonecold...
i think is 2-methylbutane as well..
if it the methyl group CH3 was placed in the first C it wouldn't be called 1-methylbutane anymore
it would be just pentane (correct me if i am wrong)
but yeah.. strange ques ...

[stonecold]

yeah we are right simon haha!
i just googled 1-methylpropane, and like i thought, it is just pentane!

[vexx]

^ yeah that question really stunk!

(CH3)₂CHCH₂CH₃

that is 2-methylbutane yeah?

book says it is 1-methylbutane, which correct me if I am wrong, is not possible?

edit: also, is this (CH₃)₂C=CH₂  2-methyl-prop-1-ene ?

i just realised how stupid what i said as, i realised it right away and you had already saw it. 1-methyl-butane would become just pentane??

and your right that's 2methyl-prop-1-ene..


edit, slow!

[stonecold]

what is the most important reason for using barium chloride over lead chloride as a precipitating reagent?

I would say because barium is less toxic than lead yeah?

edit: and also, if a fertilizer has a stated sulfur as sulfate content of 17.5%, does that mean 100g would contain 17.5g of sulfur or 17.5g of sulfate?  I am pretty sure it is the latter, but just checking!

[happyhappyland]

what is the most important reason for using barium chloride over lead chloride as a precipitating reagent?

I would say because barium is less toxic than lead yeah?

edit: and also, if a fertilizer has a stated sulfur as sulfate content of 17.5%, does that mean 100g would contain 17.5g of sulfur or 17.5g of sulfate?  I am pretty sure it is the latter, but just checking!

You must realise that when an precipate is said to be a solid it is 99.99999% solid and it is slightly soluble. In the case of lead chloride it is not very solid, infact it is soluble in hot water, therefore lead chloride would produce a smaller amount of precipate then what you assume and your answer will be understated.

[m@tty]

If a fertilizer has a stated sulfur as sulfate content of 17.5%, does that mean 100g would contain 17.5g of sulfur or 17.5g of sulfate?  I am pretty sure it is the latter, but just checking!

I am pretty sure it is the former: 17.5g sulfur per 100g. As it is referring to the sulfur within sulfate.

[stonecold]

okay.  i'm probably wrong then.  i calculated that to get 1.3g of BaSO4 precipitate you would need 3.1g fertaliser.  does that sound about right?

also why does the package have to say sulfur as sulfate, but nitrogen content can be stated on its own (i.e. not nitrogen as ammonium?)

[stonecold]

say i wanted to get ethyamine from ethene, is this a valid reaction pathway?

ethene + HCl ---> chloroethane
chloroethane + ammonia ---->ethyamine + HCl

[Mao]

say i wanted to get ethyamine from ethene, is this a valid reaction pathway?

ethene + HCl ---> chloroethane
chloroethane + ammonia ---->ethyamine + HCl

Direct addtion: ethene + NH3 --> ethylamine

[stonecold]

thanks.

the book says you have to convert to ethanol first though:

          H2O               NH3
Ethene ---> ethanol ----> ethylamine

[stonecold]

okay, i have a sac tomorrow, and just need help with this question...

The manufacturer and the procedure refer to 'the percentage by mass of sulfur present in the sample as sulfate.'  Why must the underlined words be included?

Is it because sulfur may be present in other forms as well?
Or because the sulfur is not elemental and contained in a compound?

[the.watchman]

I'm not too sure, but it could mean that sulfur is in the sample in some other form, like sulfite etc.

[stonecold]

^ yeah, that's probably what i'm going to say.  because the %nitrogen as ammonium is given because you can also have nitrogen as nitrate.

[stonecold]

is it just me, or is there something wrong with these equations.
i.e. too many or not enough hydrogen?

courtesy of the error riddled heinemann text...

and also, we aren't expected to know the structural formulae of sugars yeah?
learning the isomers of glucose would be dreadful...