This experiment will allow us to determine the molar mass of the unknown solute through calculating the difference in freezing point of the pure solvent and the solution with the unknown solute.
This lab will show case one of the colligative properties of a solution. This property is dependent upon the number of solute molecules or ions and not the identity or chemical property of the solute. A common example is water which both freezes and melts at 0°C no matter the amount of water or the size of the ice chunk.
The freezing point depression phenomenon refers to the decrease in freezing point of a solvent when a solute is added. This means that the freezing point of a solution is always lower than its pure solvent form.
Common uses for the freezing point depression are throwing rock salt onto the roads in winter and adding salt to the ice when making ice cream. Rock salt will melt the snow and prevent ice from forming because colder temperature would be need in that the freezing point has lowered. In the process of making ice cream, the dissolved salt lowers the freezing point, and in order for the ice to melt it will have to absorb more heat from the ice cream mixture thus keeping the ice cream frozen.
The relationship between the freezing point depression of a solvent and …show more content…
We will need to solve for the molality (m), number of moles of the solute per kg of solvent, by dividing ΔTf by kf. The molal freezing point depression constant, kf, is given to us for cyclohexanol at 39.4°C/m, and the ΔTf was determined experimentally using Logger Pro. Once we have that molality, we can then find the moles of solute used by multiplying the molality by the solvent used in kg. Finally, we can determine the molar mass by dividing the solute in grams added to the cyclohexanol by the moles of the solute calculated. The answer must be the molar mass of hexadecanol or
This lab will show case one of the colligative properties of a solution. This property is dependent upon the number of solute molecules or ions and not the identity or chemical property of the solute. A common example is water which both freezes and melts at 0°C no matter the amount of water or the size of the ice chunk.
The freezing point depression phenomenon refers to the decrease in freezing point of a solvent when a solute is added. This means that the freezing point of a solution is always lower than its pure solvent form.
Common uses for the freezing point depression are throwing rock salt onto the roads in winter and adding salt to the ice when making ice cream. Rock salt will melt the snow and prevent ice from forming because colder temperature would be need in that the freezing point has lowered. In the process of making ice cream, the dissolved salt lowers the freezing point, and in order for the ice to melt it will have to absorb more heat from the ice cream mixture thus keeping the ice cream frozen.
The relationship between the freezing point depression of a solvent and …show more content…
We will need to solve for the molality (m), number of moles of the solute per kg of solvent, by dividing ΔTf by kf. The molal freezing point depression constant, kf, is given to us for cyclohexanol at 39.4°C/m, and the ΔTf was determined experimentally using Logger Pro. Once we have that molality, we can then find the moles of solute used by multiplying the molality by the solvent used in kg. Finally, we can determine the molar mass by dividing the solute in grams added to the cyclohexanol by the moles of the solute calculated. The answer must be the molar mass of hexadecanol or