chem ques

[AN10]

can anybody plz solve this ques for me...i thnk im solving it wrong because my ans is weird (in decimals)

A hydrated aluminium sulfate, Al₂(SO₄)₃. xH₂O, contains 8.20% of aluminium by mass. Find the value of x.

[Ghost Of Highbury]

ok...i too am getting a wierd answer

mss of elements - Al - 17

S - 32
O - 16
H - 1

mass of elements in the hydrated salt

Al- 54
S - 96
O - 192
and water = 18x

==>

first find the total mass

54 / total *100 = 8.2

5400/ total = 8.2

total = 5400 / 8.2 = 658.53

therefore 54 + 96 + 192 + 18x = 658.53

18x = 316.53

x = 17.585

[AN10]

i got da same ans....anywayz Thanks!!

[Ghost Of Highbury]

i got da same ans....anywayz Thanks!!

welcome..
.
is the question correct??
i mean..is it exact 8.2%

[nid404]

 u write the decimal as a whole numbers...so this becomes 18 H₂O
never leave ur answer in decimals for such questions...always round it off to the nearest whole no.

[Ghost Of Highbury]

u write the decimal as a whole numbers...so this becomes 18 H₂O
never leave ur answer in decimals for such questions...always round it off to the nearest whole no.

ohh...thanks!

but is that answer and method correct?

[nid404]

u write the decimal as a whole numbers...so this becomes 18 H₂O
never leave ur answer in decimals for such questions...always round it off to the nearest whole no.

ohh...thanks!

but is that answer and method correct?

yeah absolutely