Question

When 148. mg of a certain molecular compound X are dissolved in 75.g of cyclohexane (CH), the freezing point of the solution is measured to be 59 'C. Calculate the molar mass of X If you need any additional information on cyclohexane, use only what you find in the ALEKS Data resource. Also, be sure your answer has a unit symbol, and is rounded to l significant digit. XS ?

Answer 1

Answer: The molar mass of X is 61.3g/mol

Step-by-step explanation:

Depression in freezing point is given by:

`\Delta T_f=K_f* m`

`\Delta T_f=T_f^0-T_f=(6.55^0C-5.9^0C)=0.65^0C` = Depression in freezing point

`K_f` = freezing point constant =
`20.2^0C/mol`

m= molality =
`\frac{\text{Mass of solute}}{\text{Molar mass of solute}* \text{Mass of solvent in Kg}}`

where,

Now put all the given values in this formula, we get

`0.65^0C=20.2°C/m* frac{0.148g}}{M* 0.075kg}`

`M=61.3g/mol`

Thus molar mass of X is 61.3g/mol