chemistry-neutralization

2011-06-19 6:29 pm

8.3g of asample of hydrated sodium carbonate(Na2CO3．nH2O) were dissolved in water and the solutionwas made up to 250cm^3. 25cm^3 of this solution required 29cm^3 of 0.1Msulphuric acid for complete neutralization. Calculate the n.

回答 (1)

andrew

2011-06-19 9:35 pm

✔ 最佳答案

8.3 g of asample of hydrated sodium carbonate(Na2CO3•nH2O) were dissolved in water and the solution was made up to 250 cm³.25cm³ of this solution required 29 cm³ of 0.1 M sulphuric acid for complete neutralization. Calculate the n.

Consider the titration:
Na2CO3 + H2SO4 → Na2SO4 + H2O + CO2
No. of moles of H2SO4 used = 0.1 x (29/1000) = 0.0029 mol
No. of moles of Na2CO3 in 25 cm³ of the solution = 0.0029mol

No. of moles of Na2CO3•nH2O dissolved in 25 cm³of the solution = 0.0029 mol
Mass of Na2CO3•nH2O to make 25 cm³ of thesolution = 8.3 x (25/250) = 0.83 g

Molar mass of Na2CO3•nH2O :
23x2 + 12 + 16x3 + n(1x2 + 16) = 0.83/0.0029
106 + 18n = 286
n = 10

參考: andrew

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