Prelim Chem Thread (3 Viewers)

[Shuuya]

ughhh, i'll memorise it anyway. I'm guessing it will be a multiple choice question

I've seen it come up as a multiple choice question before, so it's a good idea not to completely ignore it

 

[writeful]

Does silver always have a valence power of 1+?
And if it does, do I have to indicate it with Roman Numerals (I)?
e.g AgNO3 is silver(I) nitrate? or can I just write silver nitrate

 

[jathu123]

Does silver always have a valence power of 1+?
And if it does, do I have to indicate it with Roman Numerals (I)?
e.g AgNO3 is silver(I) nitrate? or can I just write silver nitrate

Yeah its valency is always 1+ . Since it's only 1+, you don't have to indicate it in roman numerals. So you can just write it as silver nitrate

edit: After a google search, seems like it has (+2) and (+3). But since +2 is so rare it is assumed as just +1.

 

[writeful]

Yeah its valency is always 1+ . Since it's only 1+, you don't have to indicate it in roman numerals. So you can just write it as silver nitrate

edit: After a google search, seems like it has (+2) and (+3). But since +2 is so rare it is assumed as just +1.

Thanks for confirming

 

[Carrotsticks]

http://www.porcelaingres.com/img/prodotti/collezioni/just_grey_dark_grey.jpg

 

[drsabz101]

What are the steps taken to name C4H6 ?

 

[leehuan]

What are the steps taken to name C4H6 ?

Actually, what even is C4H6?

 

[Shuuya]

Actually, what even is C4H6?

Just looked it up haha

https://www.google.com.au/search?q=...l5.2444j0j7&sourceid=chrome&es_sm=93&ie=UTF-8

 

[leehuan]

Just looked it up haha

https://www.google.com.au/search?q=...l5.2444j0j7&sourceid=chrome&es_sm=93&ie=UTF-8

Yeah and so did I and 1,3-butadiene is SO in the HSC course...

 

[Shuuya]

Yeah and so did I and 1,3-butadiene is SO in the HSC course...

In other words, don't worry about it @drsabz101

 

[drsabz101]

Okay, what about just in general finding IUPAC names for the chem prelim topic...

 

[leehuan]

Do you guys even do anything besides ionic and covalent substances?

 

[jathu123]

Isn't c4h6 butyne (regarding previous page)? I mean, it has the same formula, c4h6 right?

I'm sure it's in the prelim course, naming alkanes, alkenes and alkynes

 

[DatAtarLyfe]

Isn't c4h6 butyne (regarding previous page)? I mean, it has the same formula, c4h6 right?

I'm sure it's in the prelim course, naming alkanes, alkenes and alkynes

Correct, it's butyne
Alkynes go by the formula C(n)H(2n-2), but dont worry about them too much, you only need to know alkanes and alkenes for HSC

 

[leehuan]

For some reason I had in my head that 2n-2 = 8 instead of 2n = 8 in that rule.

But then it doesn't matter. The alkynes series are NOT important in the chemistry course.

 

[writeful]

Okay, what about just in general finding IUPAC names for the chem prelim topic...

I only know how to name simple hydrocarbons, but the steps I take are:

1. Identify if the hydrocarbon is an alkane, alkene, or and alkyne, using the general formulas (alkane is CnH2n+2, alkene is CnH2n, alkyne is CnH2n-2). This is the suffix of the hydrocarbon (e.g -ane)
2. Then identify the length of the carbon chain. That is how many carbons there are, the number n. 1=meth, 2=eth, 3=prop, 4=but and 5-10 is the general penta, hexa etc.) This is the prefix
3. Then you got the name of your hydrocarbon (e.g CH4= methane,, C2H4= ethene)
4. There's another step about where the double or triple bonds are, in the alkene and alkyne series, but I'm not too sure on that part. SO steps 1-3 is fine for alkanes

I hope that helps

 

[greenlemings]

hey whats the trend of melting and boiling point on the periodic table for metals, non metals and semi as we go down and across?

 

[eyeseeyou]

What are the solubility rules in the water topic?

 

[greenlemings]

anyone know the trend??

 

[eyeseeyou]

2. Pure substances have a constant, definite composition. Why? It cannot be separated into simpler substances by physical means. Why?
3. If there is an imbalance in chemical equation, why would we need to add extra numbers in order to balance it?
4. Why is sodium+hydrochloric acidSodium chrloride+hydrogen gas
5. Why does delta H represent a change in heat energy (enthalpy)?
6. Why does delta H < 0 represent heat energy released (exothermic)?
7. Why does delta H>0 represent heat energy absorbed (endothermic)?
8. Why are elements considered the simplest substances which cannot be broken down into further physical and chemical means?
9. Why are elements made up of only one type of atom?
10. Why are all known elements listed on the periodic table?