Question

So I'm trying to do the sodium acetate tower demonstration that I've seen a ton of videos on. I don't have sodium acetate and I am making it from a liter of 5% distilled white vinegar and pure baking soda. The vinegar is expired according to the package (though I'm not sure if this makes any difference). Although the vinegar is past the "best if used by" date it is still reacting with the baking soda. Once I hit the point where it's no longer reacting with additional baking soda I have around a liter of volume. One website recommended to slowly heat it up until it reaches about 100 - 150 mL. They recommended not boiling it with high heat as it would appear burnt. So i gently heated it up without boiling. Once it got down to around 600 ml the color started becoming noticeably yellow. Once it got down to around 400 ml the color become more of a brownish tea looking color. When it got to under 300 ml the crystals started rapidly forming. I then attempted to pour out the liquid into a new container so it could cool and I tried to filter out the existing crystals with a paper towel. I got some brown liquid but quickly the entire mixture turned into a crystally sludge. Am I doing something wrong or is this just trial and error and I need to find the exact volume at which the crystals just barely start to form and then stop heating? I know what's supposed to happen but it doesn't seem to be doing that for me. Is there a reason it's yellow/brown and not clear and does that make a difference?

Answer 1

To form a sodium acetate tower from vinegar and baking soda, gentle heating to the point of initial crystal formation is essential while avoiding overheating or contamination that leads to discoloration. Finding the exact point of saturation will allow for proper crystal growth upon cooling.

Step-by-step explanation:

When creating a sodium acetate tower through the reaction between vinegar and baking soda, it is crucial to proceed with careful precision. After adding baking soda to vinegar, which should react even if the vinegar is expired, the subsequent steps must be meticulously monitored. As you concentrate your solution by gentle heating, any discoloration, such as a yellow to brownish hue, suggests possible contamination the presence of impurities in the original vinegar or the formation of byproducts due to overheating.

The desired outcome is a clear, colorless solution that becomes supersaturated as water evaporates upon gentle heating. If the solution begins to form crystals prematurely or turns into a sludgy consistency, it indicates that the concentration process has gone too far or that the solution was overheated, likely causing the decomposition of the sodium acetate to form other compounds such as acetic acid and sodium carbonate. The key is to find the balance point at which the solution is concentrated enough to form crystals upon cooling but not so concentrated that crystals form while still hot. Using a controlled heating method, avoid caramelizing sugars or other organic compounds potentially present in the vinegar, which might result in the discoloration you observed. In the case of discoloration, it is advisable to start over with fresh materials or to ensure that any container or substance added is clean and free of contaminants. Patience and attention to heat control are essential for the successful demonstration of the sodium acetate tower.