What does the “kb” mean in a boiling point equation?

Kb is termed as Ebullioscopic constant.

Explanation:

According to Boiling point elevation phenomenon, any solution will be exhibiting higher boiling point compared to its pure solvent. So this increase in the boiling point of any liquid when a solute is added in the host is termed as boiling point elevation phenomenon. Thus, the boiling point elevation should be related with the molality of the solution b . So the ratio of increase in the boiling point or the boiling point elevation temperature to the molality of the solution gives a constant termed as ebullioscopic constant and denoted as Kb. In other words, we can state the boiling point elevation temperature is directly proportional to the molality of solution with Kb as proportionality constant.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"