chemistry question

madah123 · Post by **madah123** » Fri Jan 30, 2009 6:10 pm

i am wondering if anyone knows why Hydrangea isnt an accurate indicator for an Acid-base titration my teacher game us this question and it isnt on the book so any one knows?

MrJoey · Post by **MrJoey** » Fri Jan 30, 2009 6:40 pm

Are you sure you got the right word? Hydrangea is a flower.

madah123 · Post by **madah123** » Fri Jan 30, 2009 6:53 pm

well i am not sure if it's Hydrangea but it is aflower that if you put it in an acid it becomes red and if you put it in abase it becomes blue if you put it in aneutral it become purpil i am not sure of its name in english.
our teacher gave us this question when we were studying indicators of Acid-base titration .

chickenfeather · Post by **chickenfeather** » Fri Jan 30, 2009 7:11 pm

http://en.wikipedia.org/wiki/Hydrangea

wiki is your friend.

SM-Count · Post by **SM-Count** » Fri Jan 30, 2009 10:20 pm

Because by the time you realize you've neutralized the unknown and it's time to do calculations for 'M' you'll be dead and have over poured your known so much that you will be off the literature value by more than 100%?

Also, it's transition zone, if the google link is right, is 6.5-7.0. It's colors go red->purple->blue, not only is that difficult to read, and time consuming >.>, 6.5-7.0 is better for biochem experiments and not acid-base titrations because it's range isn't suitable. That doesn't have too much to do with accuracy, just sensitivity.

CrimsonNuker · Post by **CrimsonNuker** » Fri Jan 30, 2009 10:32 pm

SM-Count wrote:Because by the time you realize you've neutralized the unknown and it's time to do calculations for 'M' you'll be dead and have over poured your known so much that you will be off the literature value by more than 100%?

Also, it's transition zone, if the google link is right, is 6.5-7.0. It's colors go red->purple->blue, not only is that difficult to read, and time consuming >.>, 6.5-7.0 is better for biochem experiments and not acid-base titrations because it's range isn't suitable. That doesn't have too much to do with accuracy, just sensitivity.

Now thats some advanced shit

Kirkaldi · Post by **Kirkaldi** » Fri Jan 30, 2009 10:34 pm

SM-Count wrote:Because by the time you realize you've neutralized the unknown and it's time to do calculations for 'M' you'll be dead and have over poured your known so much that you will be off the literature value by more than 100%?

Also, it's transition zone, if the google link is right, is 6.5-7.0. It's colors go red->purple->blue, not only is that difficult to read, and time consuming >.>, 6.5-7.0 is better for biochem experiments and not acid-base titrations because it's range isn't suitable. That doesn't have too much to do with accuracy, just sensitivity.

lul wut

ThiefzV2 · Post by **ThiefzV2** » Fri Jan 30, 2009 10:45 pm

Kirkaldi wrote:
SM-Count wrote:Because by the time you realize you've neutralized the unknown and it's time to do calculations for 'M' you'll be dead and have over poured your known so much that you will be off the literature value by more than 100%?

Also, it's transition zone, if the google link is right, is 6.5-7.0. It's colors go red->purple->blue, not only is that difficult to read, and time consuming >.>, 6.5-7.0 is better for biochem experiments and not acid-base titrations because it's range isn't suitable. That doesn't have too much to do with accuracy, just sensitivity.

lul wut

he google and rephrase a paragraph cuz it doesnt even answer the OP question lol

StealMySoda · Post by **StealMySoda** » Sat Jan 31, 2009 3:25 am

What he's saying is that...basically it takes WAY too long to change color.
Litmus
pH
Universal indicator

Are all instant indicators.

Who the **** wants to sit around for ages for a flower to change colors.

Post by **dom** » Sat Jan 31, 2009 4:13 am

StealMySoda wrote:What he's saying is that...basically it takes WAY too long to change color.
Litmus
pH
Universal indicator

Are all instant indicators.

Who the **** wants to sit around for ages for a flower to change colors.

The Japanese

madah123 · Post by **madah123** » Sat Jan 31, 2009 8:58 am

SM-Count wrote:Because by the time you realize you've neutralized the unknown and it's time to do calculations for 'M' you'll be dead and have over poured your known so much that you will be off the literature value by more than 100%?

Also, it's transition zone, if the google link is right, is 6.5-7.0. It's colors go red->purple->blue, not only is that difficult to read, and time consuming >.>, 6.5-7.0 is better for biochem experiments and not acid-base titrations because it's range isn't suitable. That doesn't have too much to do with accuracy, just sensitivity.

so we will not know the drop that ends the titration?

takolin · Post by **takolin** » Sat Jan 31, 2009 9:14 am

It comes down to this:

A good acid/base indicator changes colour with half a drop. Yes I learned to titrate with half drops.

The times it'll take for the flower to change colour, would take too long and I doubt it's sensitive enough.
Thus you'd have to wait like 15-30 minutes after each drop to see if the colour changes.

madah123 · Post by **madah123** » Sat Jan 31, 2009 9:21 am

oh I see thanks for the answers.

ThiefzV2 · Post by **ThiefzV2** » Sun Feb 01, 2009 2:31 am

StealMySoda wrote:Who the **** wants to sit around for ages for a flower to change colors.

but i do

the OP question stated why it isnt an accurate ph indicator.

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