Answer:
The molar mass of thyroxine is 18,2 g/m
Explanation:
To solve this we must apply the colligative property of cryoscopic descent whose formula is:
T° sv pure - T° sl = Kf x molality
So let's replace our values
5,444°C - 5,144°C = 5,12 °C/m x molality
0,3°C = 5,12 °C/m x molality
0,3°C / 5,12 m/°C = molality
2,5 m
Now you should know that molality is moles from solute in 1kg of solvent but you dont have 1kg you have just 10 g. Let's convert for the rule of three
10 g = 0'010 kg
If 1 kg has 2,5 moles of thyrosine, how many for 0,010 kg
moles = (0,010kg * 2,5 moles)/1kg
moles = 0,025
Now we have the moles of thyrosine in our solution and we were informed that we dissolved 0,455 g so let's get the molar mass (mass of compound for one mole)
moles = mass/ molar mass
molar mass = mass/moles
molar mass = 0,455g/0,025 moles
molar mass = 18,2 g/m
