Ask me for chemistry help! (2 Viewers)

Hermes1

Banned
Joined
Oct 4, 2010
Messages
1,282
Gender
Male
HSC
2011
lol. u culd make a really good set of summary notes just with stuff posted in this thread.

With the production of LDPE i just say:
Initiation
Propagation
Termination
and i describe each.
with HDPE what should i say? do we even need HDPE?
 

adz1098

Member
Joined
Sep 3, 2010
Messages
55
Gender
Male
HSC
2012
A chemist wanted to find the percentage of caco3 in 2g of limewater. He added 100 ml of 0.905 mol/l HCL which was more than enough to react with with the calcium carbaonate. After the bubbling had ceased, the resulting solution was titrated with sodium carbonate solution. 30.45 ml of 1.01 mol/l was required to react with the unreacted HCL.
 

FCB

Emma Watson <3
Joined
Nov 9, 2009
Messages
563
Gender
Male
HSC
2011
- Temperature
- IF temp too high, favours the reverse reaction, decreasing yield of ammonia
- IF temp too low, not enough energy for the gases to react thus once again reducing the yield of ammonia

- Pressure
- IF pressure too high, favours the reverse reaction
- Pressure cannot be too low, as it will be expensive and dangerous
You go the pressure all wrong
 

FCB

Emma Watson <3
Joined
Nov 9, 2009
Messages
563
Gender
Male
HSC
2011
lol. u culd make a really good set of summary notes just with stuff posted in this thread.

With the production of LDPE i just say:
Initiation
Propagation
Termination
and i describe each.
with HDPE what should i say? do we even need HDPE?
Talk about Z-N catalyst
 

Qwertyuioplm

New Member
Joined
Sep 15, 2009
Messages
24
Gender
Male
HSC
2011
lol. u culd make a really good set of summary notes just with stuff posted in this thread.

With the production of LDPE i just say:
Initiation
Propagation
Termination
and i describe each.
with HDPE what should i say? do we even need HDPE?
HDPE refer to Ziegler-Natta catalyst and its low temperature and pressure (100 degree celsius, 2 atmospheres)
 
Joined
Feb 6, 2011
Messages
99
Location
Port Macquarie
Gender
Female
HSC
2011
- Temperature
- IF temp too high, favours the reverse reaction, decreasing yield of ammonia
- IF temp too low, not enough energy for the gases to react thus once again reducing the yield of ammonia

- Pressure
- IF pressure too high, favours the reverse reaction
- Pressure cannot be too low, as it will be expensive and dangerous
Pressure:
- High pressure favours the forward reaction (N2 + 3H2 <--> 2NH3)
- However high pressure is costly so it must be compromised (normally 150-250 atmospheres)

Temp:
Reaction is exothermic so will shift to reactants to absorb heat
While a low temp produces larger quantites of ammonia it takes a long time so a compromise is found (the higher the temp the faster the production (due to kinetic energy) but lower the yield) - around 450-500 C
 

Qwertyuioplm

New Member
Joined
Sep 15, 2009
Messages
24
Gender
Male
HSC
2011
has *anyone* done industrial chem?!
There be 6 marks on sulfuric acid, some marks on a synthetic molecule, some marks on Le Chateliar and some marks on saponification... don't know the rest [teacher give hints randomly through class, I write down in back of book]
 
Joined
Apr 3, 2010
Messages
777
Gender
Male
HSC
2011
There be 6 marks on sulfuric acid, some marks on a synthetic molecule, some marks on Le Chateliar and some marks on saponification... don't know the rest [teacher give hints randomly through class, I write down in back of book]
weird, but awesome nonetheless.
 

kr73114

Member
Joined
Aug 6, 2009
Messages
373
Gender
Male
HSC
2011
how do you work out the molar heat of combustion when 30% of heat is lost to surrondings?
 

Hermes1

Banned
Joined
Oct 4, 2010
Messages
1,282
Gender
Male
HSC
2011
Talk about Z-N catalyst
So in my notes this is what i say:

The polymerisation of HDPE uses an ionic ziegler-natta catalyst consisting of a mixture of compounds. In this process ethane molecules are added to the growing polymer chain on the surface of the catalyst, reducing branching.
 

mangoz

Member
Joined
Jul 17, 2011
Messages
136
Location
chicken
Gender
Male
HSC
2011
Does anyone know how TOMS work. All i remember is that it fires something into the atmosphere and that's where my thought process vanishes LOL.
 

Hermes1

Banned
Joined
Oct 4, 2010
Messages
1,282
Gender
Male
HSC
2011
TOMS is the name of a satellite instrument used to map global ozone levels.
 

oyuck

Member
Joined
Jul 6, 2011
Messages
126
Gender
Male
HSC
2011
There are 2 moles of PbI(subscript2)

Find the no of moles of I(subscript2)

Do you need to find the molar ratio molarmass(Isubscript2)/molarmass(PbI(subscript2)
??
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top