Delta T is making my solution come out negative

In summary, the molar mass of lauryl alcohol can be calculated by using the molality equation and the freezing point depression equation. The solution of 5.00 grams of lauryl alcohol in 0.100Kg of benzene froze at 4.1 degrees Celsius, which is 1.4 degrees below the freezing point of benzene. Using the freezing point depression constant for benzene, which is 5.12, the molality of the solution was calculated to be -0.27344. Then, using the molar mass formula, the molar mass of lauryl alcohol was found to be -182.855. However, it was discovered that delta T can have different meanings, and
  • #1
AMan24
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Homework Statement


Lauryl alcohol is obtained from coconut oil and is used to make detergents. A solution of 5.00 gram of lauryl alcohol in 0.100Kg of benzene freezes at 4.1 degrees Celsius. What is the molar mass of the lauryl alcohol?
Kf for benzene = 5.12, Freezing point of benzene is 5.5

Homework Equations


Molality = mol of solute/kg solvent
Delta T = (Kf) x (m)

The Attempt at a Solution


(4.1 - 5.5) = (5.12) x (m)
m = -0.27344

-0.27344 = (5.00g/mm)/0.100Kg
5/(-0.27344) x (0.100) = mm

molar mass = -182.855

So when I am doing delta t, its supposed to be final minus initial right? So I am doing the new temperature, 4.1, degrees as the final, and the unchanged or natural temperature, 5.5, as the initial. The answer would be the same thing just positive, but I am probably doing something wrong to have this negative answer. Is delta T supposed to be absolute value? Maybe its supposed to be 5.5 - 4.1, but that doesn't make sense, why would 5.5 be the final temp?

edit: I just found out that Delta T can mean different things. So for this formula, delta T is Tf^0 - Tf. So i figured it out
 
Last edited:
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  • #2
AMan24 said:
So i figured it out
Way to go.
 

What is Delta T and why is it important in scientific experiments?

Delta T, also known as temperature difference, is the difference in temperature between two points or substances. It is important in scientific experiments because it affects the rate of chemical reactions, physical changes, and can indicate the presence of energy transfer.

Why does Delta T sometimes result in a negative value in my solution?

A negative Delta T indicates that the final temperature is lower than the initial temperature. This can happen when heat is lost from the system to the surroundings, resulting in a decrease in temperature.

How does negative Delta T affect my experimental results?

Negative Delta T can affect the accuracy and precision of your experimental results. It may lead to incorrect calculations and conclusions, as well as a decrease in the rate of chemical reactions and physical changes.

How can I prevent negative Delta T in my experiments?

To prevent negative Delta T, it is important to minimize heat loss from the system. This can be done by insulating the experiment, using a closed system, or conducting the experiment in a controlled environment.

What are some common sources of error that can result in negative Delta T?

Some common sources of error that can result in negative Delta T include inaccurate temperature measurements, insufficient insulation, and heat loss due to evaporation. It is important to identify and control these sources of error to obtain reliable and accurate results.

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