# Titration calcWatch

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#1
Hey stuck again, can someone help out and explain why you multiply the EDTA mole by 1000/150 I don't get it. Below is my working

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4 years ago
#2
The number of moles of EDTA you have calculated corresponds to the number of moles of Ca2+ you have in the solution which in turn effects the moles of dissolved Ca(OH)2

Moles of Ca(2+) = moles of dissolved Ca(OH)2 = 3.325x10^-4 ( which you correctly got)

Now calculate the mass of Ca(OH)2 in grams using moles and MR

That is the mass of Ca(OH)2 in the 150cm3 sample solution

Then calculate the mass of calcium hydroxide that was dissolved that was dissolved in 1dm3
0
4 years ago
#3
You found the moles correctly but this was in 150cm3. The question is asking for the mass in 1000cm3 so you must find the moles in 1000cm3. To convert from 150cm3 to 1000cm3, you must multiply 150 by (1000/150). The moles are now in 1000cm3 so you can work out mass in 1000cm3

(Original post by Hudl)
Hey stuck again, can someone help out and explain why you multiply the EDTA mole by 1000/150 I don't get it. Below is my working

Posted from TSR Mobile
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