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# Titration question help watch

1. I understand that the RMM of potassium iodate is 214 and why they have found the concentration but I don't understand the equation that they have used. Why have they divided 4 by 214? (1.015 x 4/214)
2. (Original post by DarcyM)
I understand that the RMM of potassium iodate is 214 and why they have found the concentration but I don't understand the equation that they have used. Why have they divided 4 by 214? (1.015 x 4/214)
So you could write (1.015g x 214 gmol^-1 ) / 0.25dm^3

they have just used the fact that dividing by 0.25 is the same as multiplying by 4.
3. (Original post by MexicanKeith)
So you could write (1.015g x 214 gmol^-1 ) / 0.25dm^3

they have just used the fact that dividing by 0.25 is the same as multiplying by 4.
Thank you, but why do I want to multiply the mass by the RMM? I've never seen a formula for that
4. (Original post by DarcyM)
Thank you, but why do I want to multiply the mass by the RMM? I've never seen a formula for that
Oh sorry, that's my mistake, I'm a bit tired!

The calculation on the picture you posted is correct

1.015/(294x0.25) = (1.015x4)/ 294

So it is just the fact that 1/0.25 = 4
5. On that stage the first thing we have to do is to find the concentration in g/dm^3 . To do that since 1.015g was dissolved in 250cm^3 how many grams should be dissolved in 1dm^3 to make the same concentration . We say 4 × 1.015g = 4.060g/dm^3 . We then convert this to mol/dm^3 by dividing this value with the RMM (4.060/214 = 0.0189moldm^3)

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