What is the boiling point of a solution made by mixing 100.0g of CaCO3 with 750.0g of water?

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jerichorayel | College Teacher | (Level 2) Senior Educator

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To solve for the boiling point of the solution, we should use the formula for the boiling point elevation:

`Delta T_b = i * K_b * m`

Where:

`Delta T_b` = the boiling point elevation [T(solution) - T (solvent)]

`K_b` = ebullioscopic constant (for water = 0.512)

`m` = molality of the solution (moles of solute per kilogram of solvent) 

      = `((100 g CaCO_3) *(1 mol e CaCO_3)/(100.0869g CaCO_3))/(0.750kg)`

` `

      = 1.332 m  

`i` = van't Hoff factor (for CaCO3, i = 1)

We can substitute the values in the equation above:

`T_(solution) - T_(solvent) = (1)(0.512)(1.332) = 0.682`

  • The boiling point of pure water is 100 degrees Celsius

`T_(solution) = 100 + 0.682 = 100.682 ^o C`

Please note:

Calcium Carbonate is slightly soluble in water. If it is treated as an ionic compound, the van't Hoff factor will change. 

`i` = 2; CaCO3 will dissociate into `Ca^(2+) ` and `CO_3 ^(2-) ` ions. 

`T_(solution) - T_(solvent) = (2)(0.512)(1.332) = 1.364 `

`T_(solution) = 100 + 1.364 = 101.364 ^o C `

Sources:

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