Calculate mass of oxalic acid dihydrate (h2c2o4.2h2o)required to prepare .1m,250ml of its aqueous solution
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Answered by
5
No.
But I expect the mass to be around 30−40 g, because around 2 g is needed for a 0.05 Msolution in a 200 mL flask, if I remember correctly.
Since we want 250 mL of 1 M H2C2O4(aq), we want
1.00 mol H2C2O41 L soln×0.250L soln=0.250 mols H2C2O4
But for every one H2C2O4, there is one H2C2O4⋅2H2O, so we need 0.250 mols of specifically H2C2O4⋅2H2O that is added to some water and then filled up to the 250 mLmark on a volumetric flask.
Therefore, the mass needed is:
0.250mols H2C2O4⋅2H2O×???g1 mol H2C2O4⋅2H2O
= ???
When I worked it out, it was on the lower end of the range between 30 and 40 g. Now work it out and convince yourself that the answer lies in this range.
But I expect the mass to be around 30−40 g, because around 2 g is needed for a 0.05 Msolution in a 200 mL flask, if I remember correctly.
Since we want 250 mL of 1 M H2C2O4(aq), we want
1.00 mol H2C2O41 L soln×0.250L soln=0.250 mols H2C2O4
But for every one H2C2O4, there is one H2C2O4⋅2H2O, so we need 0.250 mols of specifically H2C2O4⋅2H2O that is added to some water and then filled up to the 250 mLmark on a volumetric flask.
Therefore, the mass needed is:
0.250mols H2C2O4⋅2H2O×???g1 mol H2C2O4⋅2H2O
= ???
When I worked it out, it was on the lower end of the range between 30 and 40 g. Now work it out and convince yourself that the answer lies in this range.
Answered by
41
Answer:
3.15
Explanation:
molarity=no of moles of solute/ volume of solution
ie, 0.1 M=n÷0.25L
n= 0.025 mol
no of moles = given mass ÷molar mass
molar mass =126 g
0.025=m÷126
m=0.025×126
=3.15 g
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