Qualification > Sciences
Chemistry Help HERE ONLY !!
ramezamgad:
the 3 rules for moles
1) No. of moles = Mass / (Mr or Ar) -----> for solids
2) No. of moles = Volume x concentration -----> for liquids
3) No. of moles = Volume / 24 -----> for gases
in the second eq. the volume should be in dm3 and conc. in mol/dm3
24 is the volume in dm3 of 1 mole of any gas at room temperature and pressure
Nanavel:
you all are SUPERB ! lil wyne >> you are guranteed an A* already ... I wish i was this awesome as you are .. double + rep
so is shogun .. I learned alot of things from you guys .. Thanx alot for helping all of us out .. Insha'llah i will get A* too >> very optimistic >> did alot of sillyness in paper 6 actually in chemistry and Biology i screwed in them not because i dont know the anwers because i am all doing the paper with hurry and excitment and i dont read full questions .. so i mess up alot
I hope i wont do any stupidity this time
aquarian93:
u guys
"what property of SO2 enables it be used as a bleaching agent?"
thanks!
hell_devil:
what r da imprtant things dat we ned 2 learn frm application part???????i don undrstand anythin frm da part....
aquarian93:
--- Quote from: ~M.J~ on May 29, 2009, 06:15:50 pm ---
--- Quote from: kam on May 29, 2009, 06:07:19 pm ---
--- Quote from: abdulrahman101 on May 29, 2009, 05:39:03 pm ---
--- Quote from: ZeroZero82 on May 28, 2009, 10:48:27 am ---how do we know if a reaction is endothermic?!
--- End quote ---
The temp would fall, this is because it takes more energy/heat to break the bonds between the atoms, if it was exothermic, then more energy would be used to form new bonds, and the temp. raises
--- End quote ---
correct me if im wrong but i thought it was the other way round
cuz endo takes in heat so temp rises(positive)
and exo gives out heat go temp falls(negative)
--- End quote ---
the heat source always has a higher temperature than the surrounding
in a redox reaction heat is not displaced it is either produced or used up
here the temperature is referred to the surrounding not the reagents
so in an exothermic reaction heat is produced which increasaes the temp. of the surrounding so the temperature is increased
--- End quote ---
so do u mean dat is according to the surrounding?
so exothermic (even if heat is given out) the temp increases
and endothermic (even if heat is absorbed) the temp decreases
so its abt the surrounding rite? ???
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