JAMB - Chemistry (1998 - No. 16)
90.0g of MgCI2 was placed in 50.0cm3 of water to give a saturated solubility of the salt is 8.0 mol dm3 at the same temperature, what is the mass of the salt left undissolved at the given temperature?
(Mg = 24, Cl = 35.5)
(Mg = 24, Cl = 35.5)
52.0g
58.5g
85.5g
88.5g
설명
Molar mass of MgCl2 = 95g
The solubility of MgCl2 is 8.0/dm3
1 dm3 = 1000cm3
Solubility of g/cm3
8 x 95 → 1000cm3
x → 50
x = (50)/(1000) x (8 x 95) / (1) = 38g
Mass of the salt left undissolved = 90 - 38 = 52.0g
The solubility of MgCl2 is 8.0/dm3
1 dm3 = 1000cm3
Solubility of g/cm3
8 x 95 → 1000cm3
x → 50
x = (50)/(1000) x (8 x 95) / (1) = 38g
Mass of the salt left undissolved = 90 - 38 = 52.0g