A sample of seawater taken from the Atlantic Ocean freezes at –2.14 °C and a sample from the Arctic Ocean freezes at –1.96 °C. Assume i = 2.
See the same question here.
https://www.jiskha.com/questions/1823034/a-sample-of-seawater-taken-from-the-atlantic-ocean-freezes-at-2-14-c-and-a-sample
How do I solve for Kf?
You are supposed to know Kf. I think that is 1.86 C/m
To find the molality of the solution, we can use the formula:
ΔTf = i * Kf * m
Where:
ΔTf is the freezing point depression,
i is the van't Hoff factor (for a non-electrolyte such as seawater, i = 1),
Kf is the cryoscopic constant for the solvent (water), and
m is the molality of the solution.
In this case, we're given ΔTf, i, and Kf, and we need to find the molality (m) of the solution.
Let's use the data provided to calculate the molality of the seawater samples from the Atlantic and Arctic Oceans.
For the Atlantic Ocean sample:
ΔTf = -2.14 °C
i = 2
Kf (for water) = 1.86 °C/m
Rearranging the formula, we have:
m = ΔTf / (i * Kf)
Substituting the values:
m = (-2.14 °C) / (2 * 1.86 °C/m)
Calculating the result:
m = -1.15 m
Therefore, the molality of the seawater sample from the Atlantic Ocean is approximately -1.15 m.
Repeat the same process for the Arctic Ocean sample:
ΔTf = -1.96 °C
i = 2
Kf (for water) = 1.86 °C/m
m = (-1.96 °C) / (2 * 1.86 °C/m)
Calculating the result:
m = -0.53 m
Therefore, the molality of the seawater sample from the Arctic Ocean is approximately -0.53 m.