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acids and bases question
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A*my
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#1
nitric acid, HNO3, and nitrous acid, HNO2 , are 2 bronsted-lowry acids containing nitrogen. a student measures the pH of 0.045 mol dm-3 solutions of HNO3 and HNO2. (pKa = 3.35) and found the acids had different pHs.
a) why are the pH different?
b) calculate the pH value of 0.045 mol dm-3 HNO3
c) calculate the pH value of 0.045 moldm-3 HNO2
I can't answer these questions? with parts b and c, I don't know how i'm meant to change the equation
a) why are the pH different?
b) calculate the pH value of 0.045 mol dm-3 HNO3
c) calculate the pH value of 0.045 moldm-3 HNO2
I can't answer these questions? with parts b and c, I don't know how i'm meant to change the equation
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Giovannii
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#2
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
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A*my
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#3
(Original post by Giovannii)
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
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A*my
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#4
(Original post by Giovannii)
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
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Giovannii
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#5
(Original post by A*my)
I just had a look at the OCR A spec to try and work out if there were any weak acids i need to learn off by heart. I couldn't see any. I only know things like CH3COOH is weak.
I just had a look at the OCR A spec to try and work out if there were any weak acids i need to learn off by heart. I couldn't see any. I only know things like CH3COOH is weak.
HCl, HNO3, H2SO4, HBr, HI, and HClO4 are all strong acids.
Most other acids will be weak acids they will give it away that it is a weak acid by giving you a Ka or pKa.
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Amethyst190
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#6
(Original post by Giovannii)
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
1) HNO3 is a strong acid so it fully dissociates H+ ions solution while HNO2 will partially dissociate H+ ions in solution.
2) In a strong acid [H+] = [HA] so you will only need to -log (H+) to get the pH
3) For a weak acid first, you work out Ka by 10^pKa. Then using that value, H+^2 will be ka x [HA] but pH is -log(H+). So you would need to square root H+ then -log it
Hope this helps
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ran-dumb
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#7
For strong acids like HNO3, concentration of acid=[H+] because we assume complete dissociation
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