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# How did i get this number!? - URGENT HELP! watch

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1. I have a quantitative practical exam tomorrow for chemistry and i have completely confused myself on my notes.

In my notes i have go the following calculations:

first second

Mass of crucible (g) : 38.00 39.74

Mass of crucible +
hydrated salt (g) 39.47 40.82

Mass of crucible +
anhydrous salt (g) 39.17 40.46

________________________________ ____________________

Mass of hydrated salt
used (38.00 - 39.47) (39.74 - 40.82)
= 1.47 = 1.08

Mass of salt formed (38.00 - 39.17) (39.74 - 40.46)
= 1.17 = 0.72

Mass of water removed
(1.17 - 1.47) (0.72 - 1.08)
= 0.30 = 0.36

________________________________ ______________________
Mean

1.47 1.08 1.28

1.17 0.72 0.98

0.30 0.36 0.33

________________________________ _________________________

Moles of water removed: 0.33/18 = 0.0183 mol

XSO4 . 5H2O --> formulae of (-) ion = SO4 2- Formulae of (+) ion = X2+
________________________________ __________________________

Moles of XSO4 Formed: Ration - XSO4 - 1 : 5 - 5H2O

N= M/Mr = 0.0183/ 5 = 0.00366 moles

THE BIT I DONT UNDERSTAND

MOLAR MASS OF X: Mr = M/N 0.95 / 0.00366

Where does the mass 0.95 come from???

Please help me urgently! as i cannot continue the calculation until i understand how i got this?
2. (sorry for the messed up layout - the numbers next to each other are the first test and the second test )
3. I assume it will be mass of anhydrous salt, take away the mass of water driven off from the mass of the hydrated salt?
4. (Original post by matthew769)
I assume it will be mass of anhydrous salt, take away the mass of water driven off from the mass of the hydrated salt?
ahh thank you so much!!

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