Bioling point elevation

Question

In making candy, a certain recipe calls for heating an aqueous sucrose solution to the softball stage, which has a boiling point of 235-240 F. What is the range of mass percentages of the solution of sugar (C12H22O11) that boils at those two temperatures?

Answer 1

ΔT_bp=i K_b m (where m=molality=moles solute (sucrose)/kg solvent (water)) , ΔTbp is in Celsius

ΔTbp for 235F = 112.778-100=12.778 ºC

m for 235 F = 12.778/ 0.512=24.957 m so in 1Kg (1000g) of water you have 24.957 moles sucrose = 24.957 * 342 g/mol= 8535 grams

 

mass percent sucrose = 100*mass sucrose/total mass solution=100*8535/(8535+1000g water)= 89%

 

solve similarly for 240 F to find your range!