Two questions

用戶85377

2007-10-20 8:48 pm

1. The mass of Zn containing the same number of atoms as there are in 12.7 g of S atoms.
2. The mass of water which contains the same number of molecules as 2.2 g of CO2.

更新1:

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更新2:

Very urgent~~~~~~

回答 (1)

Uncle Michael

2007-10-21 3:30 am

✔ 最佳答案

1.
Molar mass of S = 32.1 g mol-1
Molar mass of Zn = 65.4 g mol-1

No. of moles of S atoms = mass/(molar mass) = 12.7/32.1 = 0.396 mol

No. of Zn atoms = No. of S atoms
Hence, No. of moles of Zn atoms = No. of moles of S atoms

No. of moles of Zn atoms = 0.396 mol
Mass of Zn atoms = mol x (molar mass) = 0.396 x 65.4 = 25.9 g

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2.
Molar mass of H2O = 1x2 + 16 = 18 g mol-1
Molar mass of CO2 = 12 + 16x2 = 44 g mol-1

No. of moles of CO2 molecules = mass/(molar mass) = 2.2/44 = 0.05 mol

No. of H2O molecules = No. of CO2 molecules
Hence, No. of moles of H2O molecules = No. of moles of CO2 molecules

No. of moles of H2O molecules = 0.05 mol
Mass of H2O molecules = mol x (molar mass) = 0.05 x 18 = 0.9 g

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