Chemistry

2011-11-28 7:23 am
0.985g of an anhydrous metal carbonate (formulaXCO3) required 40.00cm^3 of 0.250M hydrochloric acid for complete neutralization.Calculate the relative atomic mass of the maetal X.

回答 (1)

2011-11-28 7:33 am
✔ 最佳答案
X should have a charge with 2+ as it can chemically combine with CO3^2- to form XCO3.
Therefore, the chemical equation becomes:
XCO3 + 2HCl ---> XCl2 + H2O + CO2
No. of moles of HCl
= 0.25 * 40/1000
= 0.01 mol
No. of moles of XCO3
= 0.01 / 2
= 5*10^-3 mol
Let x be the relative atomic mass of X.
since no. of moles = mass / molar mass,
we have 5*10^-3 = 0.985 / (x + 12 + 16*3)
On solving, x = 137
Hence the relative atomic mass of X is 137.
Note that the relative atomic mass has no unit.
參考: Knowledge is power.


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