# Chemistry homework help?

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Thread starter 1 week ago
#1
Hi! I keep getting somewhat close to the answer but im not sure how to get the correct one.

1.96g of an unknown hydroxide X(OH)2 was dissolved in water and the solution was made up to 250cm³ in a volumetric flask. In a titration, 25 cm³ of this solution of X(OH)2 required 21.2cm³ of 0.250 moldm³ HCl
2HCl + X(OH)2 ---> XCl2 + 2H2O
Identify the unknown hydroxide.

As the Mr of X(OH)2 i keep getting around 740 even though in the textbook it says 74.

My working out:
Mol of HCl = 0.0053 mol
Mol of X(OH)2 = 0.00265 mol
1.96/0.00265=739.622...
0
1 week ago
#2
(Original post by arti_k)
Hi! I keep getting somewhat close to the answer but im not sure how to get the correct one.

1.96g of an unknown hydroxide X(OH)2 was dissolved in water and the solution was made up to 250cm³ in a volumetric flask. In a titration, 25 cm³ of this solution of X(OH)2 required 21.2cm³ of 0.250 moldm³ HCl
2HCl + X(OH)2 ---> XCl2 + 2H2O
Identify the unknown hydroxide.

As the Mr of X(OH)2 i keep getting around 740 even though in the textbook it says 74.

My working out:
Mol of HCl = 0.0053 mol
Mol of X(OH)2 = 0.00265 mol
1.96/0.00265=739.622...
The mol of X(OH)2 you calculated is for the 25cm3 solution. Multiply the mole by 10 to get the number of moles in the 250cm3 solution which was the original.
1
Thread starter 1 week ago
#3
(Original post by Inina)
The mol of X(OH)2 you calculated is for the 25cm3 solution. Multiply the mole by 10 to get the number of moles in the 250cm3 solution which was the original.
that makes so much sense!! thank youu
1
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