« previous next »
Pages: [1] 2 3   Go Down

Author Topic: Moles Again...  (Read 4554 times)

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Moles Again...
« on: September 10, 2009, 02:16:59 pm »
I am sure abt his question as my teacher had given me this one it is not like the previous one..
Here it starts
>>>>>>>>>>>>>>>>
9.3g of impure Sodium bicarbonate[NaHCO3] was heated and 2.2g of CO2 was formed.
Calculate % purity of NAHCO3
pls hepl!!!
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: Moles Again...
« Reply #1 on: September 10, 2009, 02:24:47 pm »
Quote from: shreyapril on September 10, 2009, 02:16:59 pm
I am sure abt his question as my teacher had given me this one it is not like the previous one..
Here it starts
>>>>>>>>>>>>>>>>
9.3g of impure Sodium bicarbonate[NaHCO3] was heated and 2.2g of CO2 was formed.
Calculate % purity of NAHCO3
pls hepl!!!

molar mass or CO2 is 12+2*16=44 so 2.2/44=0.05 moles of CO2 so .05 moles of NAHCO3. 1 mol of NaHCO3 weighs 23+1+60=84 and 0.5 moles weighs 0.05*84=4.2g

Purity =4.2/9.3=4.5=45%
Logged

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: Moles Again...
« Reply #2 on: September 10, 2009, 02:32:01 pm »
oops sorry
i typed the question wrong again..
it is 2.24g not 2.2
sry a silly mistake.
cant understand my own handwritting..
but thanx for the steps astar.
they will help me find the ans
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #3 on: September 10, 2009, 03:16:18 pm »
Quote from: shreyapril on September 10, 2009, 02:32:01 pm
oops sorry
i typed the question wrong again..
it is 2.24g not 2.2
sry a silly mistake.
cant understand my own handwritting..
but thanx for the steps astar.
they will help me find the ans
doesnt change the answer much

46%
Logged
divine intervention!

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: Moles Again...
« Reply #4 on: September 10, 2009, 03:17:54 pm »
i got some wierd ans wen i tried it the way a star told me
i got something near to 98.28% purity
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #5 on: September 10, 2009, 03:18:55 pm »
Quote from: shreyapril on September 10, 2009, 02:16:59 pm
I am sure abt his question as my teacher had given me this one it is not like the previous one..
Here it starts
>>>>>>>>>>>>>>>>
9.3g of impure Sodium bicarbonate[NaHCO3] was heated and 2.2g of CO2 was formed.
Calculate % purity of NAHCO3
pls hepl!!!
a simpler way of diong this is use ratio proportion

44g of CO2 is produced with - 84g of pure NAHCO3

therefore 2.24g of CO2 should be produced with - 84*2/44 * 2.24 = 8.55

8.55 / 9.2 * 100 = 93%
« Last Edit: September 10, 2009, 03:34:35 pm by eddie_adi619 »
Logged
divine intervention!

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: Moles Again...
« Reply #6 on: September 10, 2009, 03:27:09 pm »
oye it shud be 84*2
the equation for the same is..
2NaHCO3 --> Na2CO3 + CO2 + H2O

k..
so acc to u it will be
168/44*2.24=8.55
so purity wud be 8.55/9.3*100=91.96 [app]
« Last Edit: September 10, 2009, 03:29:41 pm by shreyapril »
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #7 on: September 10, 2009, 03:29:28 pm »
Quote from: shreyapril on September 10, 2009, 03:27:09 pm
oye it shud be 84*2
the equation for the same is..
2NaHCO3 --> Na2CO3 + CO2 + H2O
oh..missed that..
u shud have ritten the whole equation

astar missed it too..

u just rote CO2

yes its 84*2
Logged
divine intervention!

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #8 on: September 10, 2009, 03:31:44 pm »
Quote from: eddie_adi619 on September 10, 2009, 03:29:28 pm
Quote from: shreyapril on September 10, 2009, 03:27:09 pm
oye it shud be 84*2
the equation for the same is..
2NaHCO3 --> Na2CO3 + CO2 + H2O
oh..missed that..
u shud have ritten the whole equation

astar missed it too..

u just rote CO2

yes its 84*2
i'm getting 92%
Logged
divine intervention!

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #9 on: September 10, 2009, 03:32:42 pm »
Quote from: shreyapril on September 10, 2009, 03:27:09 pm
oye it shud be 84*2
the equation for the same is..
2NaHCO3 --> Na2CO3 + CO2 + H2O

k..
so acc to u it will be
168/44*2.24=8.55
so purity wud be 8.55/9.3*100=91.96 [app]
yes
thats wat i rote
Logged
divine intervention!

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #10 on: September 10, 2009, 03:33:26 pm »
Quote from: shreyapril on September 10, 2009, 03:17:54 pm
i got some wierd ans wen i tried it the way a star told me
i got something near to 98.28% purity
how ddid u get

98%
Logged
divine intervention!

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: Moles Again...
« Reply #11 on: September 10, 2009, 03:33:53 pm »
ohh
but i think u had written 46 not 92 if i am not wrong..
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline Ghost Of Highbury

  • O_o_O lala!
  • SF Farseer
  • *******
  • Posts: 4096
  • Reputation: 41428
  • Gender: Male
  • Namaskaram!
Re: Moles Again...
« Reply #12 on: September 10, 2009, 03:35:03 pm »
Quote from: eddie_adi619 on September 10, 2009, 03:31:44 pm
Quote from: eddie_adi619 on September 10, 2009, 03:29:28 pm
Quote from: shreyapril on September 10, 2009, 03:27:09 pm
oye it shud be 84*2
the equation for the same is..
2NaHCO3 --> Na2CO3 + CO2 + H2O
oh..missed that..
u shud have ritten the whole equation

astar missed it too..

u just rote CO2

yes its 84*2
i'm getting 92%
chk this
Logged
divine intervention!

Offline ~~~~shreyapril~~~~

  • SF Master
  • ******
  • Posts: 2606
  • Reputation: 2640
  • Gender: Male
  • "Prototype"
Re: Moles Again...
« Reply #13 on: September 10, 2009, 03:36:23 pm »
Mr of NAHCO3 is 168         Mr of CO2 is 44
Mass of NAHCO3 is 9.3        Mass of Na2CO3 is 5.9    mass of CO2 is 2.24        mass of H2O is 1
                5.9+1+2.24=9.14
        9.14/9.3*100=98.28[app]
Logged
Friendship is like peeing on yourself. Everyone can see it but only you get the warm feeling that it gives :D :P :)

Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: Moles Again...
« Reply #14 on: September 10, 2009, 03:38:49 pm »
i THOUGHT THE EQUATION WOULD BE NaOH3=NaOH+CO2

Which make the ratio 1:1
Logged
Pages: [1] 2 3   Go Up
« previous next »