Chem(Help)

2008-05-04 2:37 am

6.30g of a dibasic acid H2X are dissolved in water. Then the solution is made up to 250.0 cm3. 25.0 cm3 of this acid solution can neutralize 20.0 cm3 of 0
500M potassium hydroxide solution completely.
a) Find the relative molecular mass of the acid.
b) Find the relative atomic mass of X.
(Relative atomic mass: H=1.0)

0.50g of a sample of solid sodium hydroxide containing some sodium choloride are dissolved in water. 22.0 cm3 of 0.50 M nitric acid are required to completely neutralize the sample. Calculate the percentage purity of the sodium hydroxide in the sample
(Relative atomic masses: H=1.0, O=16.0, Na= 23.0)

想問吓是不是要寫equation, 唔該寫埋.

回答 (1)

用戶7369

2008-05-04 2:56 am

✔ 最佳答案

1. H2X +2KOH ---->2 H2O + K2X
a) the no. of mole of hydroxide used=20/1000x0.5
the no. of mole of acid used=1/2x20/1000x0.5
the total no. of mole of acid = 10x1/2x20/1000x0.5
=0.05
0.05mole=6.3g
1mole=6.3/0.05=126
b) the relative atomic mass ofX =126-2=124
2. NaOH +HNO3-------> NaNO3 + H2O
the no. of mole of nitric acid used=22/1000x0.5
the no. of mole of sodium hydroxide=22/1000x0.5
the mass of sodium hydroxide used=40x22/1000x0.5=0.44g
% purity of sodium hydroxide =0.44/0.5x100%=88%

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