riley.xx
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please can someone help with the attached questions
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ilovephysmath
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(Original post by HiMyNameIsRiley)
please can someone help with the attached questions
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Okay, for part (a) what role does the concentration of a base play? Hint: what does the concentration of an acid determine?
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(Original post by ilovephysmath)
Okay, for part (a) what role does the concentration of a base play? Hint: what does the concentration of an acid determine?
does the concentration determine how much the reagent will dissociate?
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(Original post by HiMyNameIsRiley)
does the concentration determine how much the reagent will dissociate?
Nope. pH, remember?
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riley.xx
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(Original post by ilovephysmath)
Nope. pH, remember?
oh yeah, so if the concentration of NaOH is 0.100 mol dm-3 does this mean pOH is -log(0.1) = 1 ?
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(Original post by HiMyNameIsRiley)
oh yeah, so if the concentration of NaOH is 0.100 mol dm-3 does this mean pOH is -log(0.1) = 1 ?
Yes. And then...?
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(Original post by ilovephysmath)
Oh yeah sorry my bad, yes pOH is 1
ok, and since pH=14-pOH, pH would be 13? and on the graph the line goes to 13; pH tends to 13, indicating that the conc. of NaOH is 0.100 mol dm-3. Is that correct?
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(Original post by HiMyNameIsRiley)
ok, and since pH=14-pOH, pH would be 13? and on the graph the line goes to 13; pH tends to 13, indicating that the conc. of NaOH is 0.100 mol dm-3. Is that correct?
Bingo! There you go
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Okay, now for part b. How do you think we’re supposed to approach the question? Where is the ‘endpoint’?
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riley.xx
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(Original post by ilovephysmath)
Bingo! There you go
yay!! thanks
(Original post by ilovephysmath)
Okay, now for part b. How do you think we’re supposed to approach the question? Where is the ‘endpoint’?
i think the end point is the vertical line? so when the pH is between 6-10 ?
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(Original post by HiMyNameIsRiley)
yay!! thanks

i think the end point is the vertical line? so when the pH is between 6-10 ?
Yes, the endpoint lies halfway up the vertical line. What will you do next?
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(Original post by ilovephysmath)
Yes, the endpoint lies halfway up the vertical line. What will you do next?
like draw a line from that point downwards to the x-axis?
would the volume of CH3COOH be 25cm3 ?
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(Original post by HiMyNameIsRiley)
like draw a line from that point downwards to the x-axis?
would the volume of CH3COOH be 25cm3 ?
Yes!
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(Original post by HiMyNameIsRiley)
like draw a line from that point downwards to the x-axis?
would the volume of CH3COOH be 25cm3 ?
Okay part c now. Do you know what boxes an indicator should tick to be suitable for a titration??
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(Original post by ilovephysmath)
Okay part c now. Do you know what boxes an indicator should tick to be suitable for a titration??
the indicator has to have a colour change in the same pH range as the vertical line section of the curve?
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(Original post by HiMyNameIsRiley)
the indicator has to have a colour change in the same pH range as the vertical line section of the curve?
Yes, and you can use your data booklet to find that indicator
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(Original post by HiMyNameIsRiley)
the indicator has to have a colour change in the same pH range as the vertical line section of the curve?
Part d. There are two ways h2so4 is different from ch3cooh. What do you think those two ways are?
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(Original post by ilovephysmath)
Part d. There are two ways h2so4 is different from ch3cooh. What do you think those two ways are?
-its a strong acid, CH3COOH is a weak acid
-so therefore it will fully dissociate, unlike CH3COOH
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(Original post by HiMyNameIsRiley)
-its a strong acid, CH3COOH is a weak acid
-so therefore it will fully dissociate, unlike CH3COOH
Yes, and? The second point is just an elaboration of the first. Hint: the first dissociation of H2SO4 is complete.....
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another hint: H2SO4 is diprotic. How will that affect the titration curve?
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