JAMB - Chemistry (2004 - No. 17)
The solubility in moldm\(^{-3}\) of 20g of CuSO\(_4\) dissolved in 100g of water at 180\(^o\)C is
[Cu = 64, S = 32, O =16]
[Cu = 64, S = 32, O =16]
0.13
0.25
1.25
2.00
Giải thích
Relative molecular mass of CuSO\(_4\) = 64 + 32 + (16 x 4) = 160
The number of moles of CuSO\(_4\) = \(\frac{mass}{Molar mass}\)
= \(\frac{20}{160}\)
n = 0.125 mole
100g of water dissolved 0.125mole of CuSO\(_4\)
100g of water will dissolve \(\frac{0.125}{100}\times{1000}\)
Solubility = 1.25 moldm\(^{-3}\)
Alternatively,
Solubility = Number of moles of solute x \(\frac{1000}{Volume of solvent}\)
But Number of moles of solute = \(\frac{mass}{molar mass}\) = \(\frac{20}{160}\) = 0.125 moles
Solubility = Number of moles of solute x \(\frac{1000}{Volume of solvent}\)
Solubility = 0.125 x \(\frac{1000}{100}\)
= 1.25 moldm\(^{-3}\)