# Freezing Salt Water Experiment

• Edward1
In summary, you will not be able to accelerate the freezing of salt water with electrodes. If you want to freeze salt water, you will need to add salt to the water, lower the freezing point, or use a condenser.
Edward1
I'm in a bit of a time crunch for science fair, and there are still a few questions about my experiment that are unanswered. What I'm dong is trying to accelerate the freezing of salt water by adding electrodes to the bottom of my container (attached to a battery). If the ions of the salt are attracted to the positive and negative electrodes, that should increase the salinity of the water near the bottom of the container, and decrease the salinity of the water near the top. I'll put my samples in the freezer, and periodically check on them to measure the thickness of ice formed.

Since I don't want electrolysis to occur, will insulating the electrodes work? As well, if I'm insulating the electrodes, will there be electrical charge to attract the ions?

Someone suggest to me instead of connecting electrodes the the battery, just build a small capacitator in the water. I think that this would be less bulky than wires from a battery. Any details on how this might work?

Also does anyone have a general time scale for how long it takes ice to freeze from water and salt water?

Thanks

Have you checked the numbers? How much ions will concentrate around electrodes and how large the concentration change will be?

Even if you were using kilovolts, concentration changes would be almost undetectable, especially as they will be present only on the electrode surface (google for double layer), not in the bulk of the solution.

This science experiment will not work. The concentration of salt particles to water in seawater (pretty salty) is 35000/million, or 35g/L (http://en.wikipedia.org/wiki/Saline_water). If you were try to saturate your water with salt, to maximize the salinity (and thus, the ions), you would max out at around 26% salinity. Additionally, by adding salt to water, you are actually lowering the freezing point (i.e., making it harder for the solution to freeze (The freezing point is −21.12 °C for 23.31 wt% of salt from http://en.wikipedia.org/wiki/Sodium_chloride)). Essentially, a normal amount of salt and you will have a very negligible % of ionized solution even POSSIBLE to be drawn towards the electrodes, and too much salt and you've brought the freezing point down to −21.12 °C, probably much colder than your freezer goes.

Also, the time water takes to freeze is variable based on the surface area of the structure holding the water, ambient temperature of the water, and temperature/structure of the freezer (is it windy in your freezer? if so, things will freeze faster. no wind? slower).

This is a bad science project idea, you should try something else.

## 1. How does salt affect the freezing point of water?

Salt lowers the freezing point of water by disrupting the formation of ice crystals. This is because the presence of salt in water prevents the water molecules from arranging themselves into a solid structure, making it more difficult for the water to freeze.

## 2. What materials are needed for a freezing salt water experiment?

The materials needed for a freezing salt water experiment include salt, water, a container, a thermometer, and a freezer. You can also add food coloring if you want to make the experiment more visually interesting.

## 3. How do you set up the freezing salt water experiment?

To set up the experiment, mix salt and water in a container and stir until the salt is completely dissolved. Place the thermometer in the solution and place the container in the freezer. Record the temperature of the solution every 5 minutes until it freezes.

## 4. What are the results of the freezing salt water experiment?

The results of the experiment will show that the salt water solution will take longer to freeze compared to pure water. This is because the salt lowers the freezing point of water, causing it to require a lower temperature to solidify.

## 5. What is the significance of the freezing salt water experiment?

The freezing salt water experiment is significant because it demonstrates the effects of a solute (salt) on the properties of a solvent (water). It also highlights the importance of understanding colligative properties in chemistry, which are properties that depend on the number of particles in a solution rather than the type of particles. This experiment is also commonly used to teach about the freezing point depression phenomenon.

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