chem 98年第6題!!

Question

圖:

http://xa9.xanga.com/2c2c76e340032181329971/z13866...

a(i)(3)點做???

thx~

Update:

但chem書話alkaline係red,neutral係very pale pink,acidic先係colourless喎??!!

如果你話neutral係colourless,咁acidic係咩顏色??

Answer 1

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During titration, the pH indicator (phenolphthalein) shouldbe put in the known solution, in this case, it is the 1M sodium hydroxidesolution, which is alkaline.

Inside an alkaline medium, phenolphthalein will have a pinkcolour.

At the end point of the titration (this time isneutralization of diluted nitric acid and sodium hydroxide solution), the pHvalue of the mixture will be lower.

The colour change at the end point is from pink to colourless.

Source(s): Myself~~~