im working on \" iodine clock reaction lab\" for chem and right now i\'m suppose

Question

im working on " iodine clock reaction lab" for chem and right now i'm suppose to figure out KIO3 concentration

the KIO3 bottle said it has 4.3g of KIO3 with 1L of vol. so, in my class prof said [kio3]= (molar mass x mass on bottle) x 1L and IF i do this, i get large molarity which is like 920M ..insane i have no idea what i did wrong here b/c 920M doesn't seem right though. any thoughts?

after this i'm suppose to use m1v1=m2v2 to figure out m2 of KIO3 for example, trial#1 we used 10mL of starch and 80mL KIO3 and 10mL water add up to total 100mL volume

Explanation / Answer

Let me show in steps calculation of Molarity

First step we calculate moles by formula  

Number of moles of KIO3 = mass of KIO3 / Molar mass of KIO3

= ( 4.3g) / ( 214 g/mol) = 0.02 mol

Molarity of KIO3 = ( moles of KIO3) / ( solution volume in L)

= ( 0.02 mol / 1L) = 0.02 M

now 2nd part we find final Molarity after dilution

Initial Molarity M1 = 0.02 M , initial volume = 80 ml , final volume = 100 ml we find M2 i.e final molarity after diluton

0.02 M x 80 ml = M2 x 100 ml

M2 = ( 0.02 x 80 /100) = 0.016 M

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