Qualification > Sciences
Any Chem AS question to be posted here :):)
Haaks18:
Thanks for answering :p
Deadly_king:
--- Quote from: Haaks18 on November 28, 2010, 04:22:52 am ---Is This Chemistry AS edexcel :/
--- End quote ---
Nope that is A2. ;)
Good job daughter. ;D
Amelia:
--- Quote from: Martin Luther King Jr on November 30, 2010, 05:04:55 am ---Nope that is A2. ;)
Good job daughter. ;D
--- End quote ---
You just made me smile. ;D :D
AS-Girl:
here are 2 questions :
1) If the pH of a tomato juice is 4.50, then the hydroxide ion concentartion [OH]- of the juice is:
a) 3.16X 10^(-5) mole/litre
b)1.00X 10^(-14) mole/litre
c) 3.16X10^(-9) mole/litre
d) 1.00X 10^(-7) mole/litre
2)How many ions per formula unit would you find if you dissolve (NH4)2[Ce(NO3)6] in water?
a) 3
b)9
c) 2
d) 6
Thanks in advance :)
tmisterr:
--- Quote from: AS-Girl on December 09, 2010, 06:54:48 pm ---here are 2 questions :
1) If the pH of a tomato juice is 4.50, then the hydroxide ion concentartion [OH]- of the juice is:
a) 3.16X 10^(-5) mole/litre
b)1.00X 10^(-14) mole/litre
c) 3.16X10^(-9) mole/litre
d) 1.00X 10^(-7) mole/litre
2)How many ions per formula unit would you find if you dissolve (NH4)2[Ce(NO3)6] in water?
a) 3
b)9
c) 2
d) 6
Thanks in advance :)
--- End quote ---
1. hmm, i'm getting an answer not included in the choices......Since pH is -log[H+], we need to un-log the pH value to find the hydrogen ion concentration. which is 10-4.5= 3.16x10-5. since the tomato juice is in aqueous form and we know the ionic product of water (assuming it is at rtp its value is 1x10-14), we can use it to find the hydroxide ion concentration. Kw=[H+]*[OH-] so [OH-]=Kw/[H+] which is 1x10-14/3.16x10-5=3.16x10-10
2. it will dissolve into 2NH4+ and the complex ion [Ce(NO3)6]2- where NO3 is the ligand, assuming that it completely dissociates. so 2 ammonium ions and one complex ion to give a total of 3 ions per unit formula so a is your answer
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