Multiple choice-Q14

Mark576 · 7 Nov 2008, 10:28 PM

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yeah I put (b). the question is pretty standard

Aaron.Judd · 7 Nov 2008, 11:15 PM

The answer is C. d9684 pm me, tell me who you are and if I like you I'll reveal my identity proving I do (or did) go to JRAHS.

iEdd · 8 Nov 2008, 9:05 AM

Yes, we already know that you think that there is no such thing as diluting acids. You think the answer is C, because you believe if I put one drop of HCl in a pool, the pH of the whole pool will be 1. Actually, let's make a similar actual question:

100mL of 1M HCl is added to a 50 000L swimming pool. What is the pH of the final solution?

b) pH=5.7, as H⁺ concentration was calculated in 50L
c) pH=1, as there were that many H⁺ ions in the original 100mL

Let me guess, Mrs Pooviah says it's C?

dp624 · 8 Nov 2008, 9:13 AM

Quote:

Originally Posted by Aaron.Judd

The answer is C. d9684 pm me, tell me who you are and if I like you I'll reveal my identity proving I do (or did) go to JRAHS.

PM'ed

drobby · 8 Nov 2008, 8:43 PM

Quote:

Originally Posted by Kearnzo

n(H+ in HCl)= 0.02 x 0.08 = 1.6x10^-3

n(OH- in NaOH)= 0.03 x 0.05 = 1.5x10^-3

That is right

But 0.0016 - 0.0015 is 0.0001

This is number of moles of H+ ions left in the solutions

Ph = -log10[H+]

c = n/v

volume is 20mls +30 mls = 0.05 L

therefore [H+] is 0.0001/0.05 = 0.002

Ph = -log10[0.002] is equal to 2.69... = 2.7

did the same and got c

iEdd · 8 Nov 2008, 8:50 PM

You forgot to divide by .050L

eddy11 · 8 Nov 2008, 9:11 PM

its C, i initially put B but its painfully obvious its C having realised that i forgot to caculate the [H+] and rather just the number of moles of H+ ions.

iEdd · 8 Nov 2008, 9:20 PM

Um, swap where you said B and C.

C is what you put if you forget to find concentration.

nswchu123 · 11 Nov 2008, 9:27 AM

It's B.

Pls refer to Kearnzo's calculation.
pH = - log [H+]

View Poll Results: Answer to Q14 multi
a)	3	2.27%
b)	59	44.70%
c)	53	40.15%
d)	17	12.88%
Voters: 132. You may not vote on this poll

7 Nov 2008, 10:28 PM	#46 (permalink)
Mark576 Feel good ... HSC: 2008 Gender: Male Join Date: Jul 2006 Posts: 521 Last Activity: 17 Mar 2010, 7:08 PM	Re: Multiple choice-Q14 You can hide this advertisement by registering. yeah I put (b). the question is pretty standard __________________

7 Nov 2008, 11:15 PM	#47 (permalink)
Aaron.Judd Senior Member HSC: 2008 Gender: Male Join Date: Aug 2008 Posts: 373 Last Activity: 5 Apr 2009, 4:24 PM	Re: Multiple choice-Q14 The answer is C. d9684 pm me, tell me who you are and if I like you I'll reveal my identity proving I do (or did) go to JRAHS. __________________ Aaron Judd, 2008 HSC

8 Nov 2008, 9:05 AM	#48 (permalink)
iEdd Executive Member HSC: 2008 Gender: Male Location: NSW Join Date: Sep 2006 Posts: 414 Last Activity: 16 Mar 2010, 9:38 AM	Re: Multiple choice-Q14 Yes, we already know that you think that there is no such thing as diluting acids. You think the answer is C, because you believe if I put one drop of HCl in a pool, the pH of the whole pool will be 1. Actually, let's make a similar actual question: 100mL of 1M HCl is added to a 50 000L swimming pool. What is the pH of the final solution? b) pH=5.7, as H⁺ concentration was calculated in 50L c) pH=1, as there were that many H⁺ ions in the original 100mL Let me guess, Mrs Pooviah says it's C?

8 Nov 2008, 8:50 PM	#51 (permalink)
iEdd Executive Member HSC: 2008 Gender: Male Location: NSW Join Date: Sep 2006 Posts: 414 Last Activity: 16 Mar 2010, 9:38 AM	Re: Multiple choice-Q14 You forgot to divide by .050L

8 Nov 2008, 9:11 PM	#52 (permalink)
eddy11 Member HSC: 2008 Gender: Male Join Date: Aug 2007 Posts: 121 Last Activity: 2 Mar 2010, 12:19 PM	Re: Multiple choice-Q14 its C, i initially put B but its painfully obvious its C having realised that i forgot to caculate the [H+] and rather just the number of moles of H+ ions. __________________ Chemistry Mathematics Mathematics ext. 1 Biology English adv. SOR1 UAI aim: +95 Little Willie was a chemist, Little Willie is no more, what he thought was H20 was H2S04

8 Nov 2008, 9:20 PM	#53 (permalink)
iEdd Executive Member HSC: 2008 Gender: Male Location: NSW Join Date: Sep 2006 Posts: 414 Last Activity: 16 Mar 2010, 9:38 AM	Re: Multiple choice-Q14 Um, swap where you said B and C. C is what you put if you forget to find concentration.

11 Nov 2008, 9:27 AM	#54 (permalink)
nswchu123 New Member HSC: 2010 Gender: Male Join Date: Jun 2007 Posts: 1 Last Activity: 24 Nov 2009, 12:31 PM	Re: Multiple choice-Q14 It's B. Pls refer to Kearnzo's calculation. pH = - log [H+]

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