Discussion on laboratory drip rate control
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I have been making magnesium hydroxide whiskers recently. During the experiment, I found it difficult to control the dripping speed of alkali, so I considered two methods.: 1. Use the stopcock of a separatory funnel or buret for control. 2. Use the hospital infusion controller to modify the buret for control. However, in the first option, the drip speed will change if the cock is accidentally touched during use. In the second option, the infusion tube will become hard with use, and usually the drip speed will change again after half an hour. If anyone has a better plan that can be modified using laboratory equipment, you might as well share it and discuss it.
I have been engaged in chemical analysis. Once, I did a small test and required to drop 10ml of TEA in about an hour. I achieved this requirement by adjusting the size of the cock. From what you said, your practical operation ability needs to be improved. I don’t know how much alkali solution you consume at one time. Generally, analysts can titrate half a drop to the end, and half a drop is usually 0.025ml. Think about it, can you solve the problem of dripping speed?
How can it be so complicated? Just use a burette and drop it slowly! You can go as slow as you want!
It can be adjusted with the cock. The key is to control the cock well. You can try it several times by yourself.
The dripping process mentioned by the poster is not the titration process we usually analyze. It takes a long time and requires a relatively constant but slow dripping speed, right? I have experienced a similar washing process. Since the liquid level in the tube is relatively high at the beginning, the solution pressure is relatively high. After the speed is adjusted, the dripping speed will become smaller due to the lower liquid level, lower hydraulic pressure and smaller pressure. Moreover, using a piston to control the flow rate can easily cause the flow rate to change due to a slight change in the piston position, which is indeed a problem. There are two solutions: 1. Use screw water stop clamps to control the flow rate to prevent changes in the water flow channel. ； 2. Use a container with a diameter much larger than the diameter of the outflow pipe to hold the dripping solution, so that the liquid level of the container holding the dripping solution does not change significantly during the entire dripping process. This post was last edited by xwtsq on 2009-4-2 23:01 ]
It is best to connect a latex tube and use a solenoid valve to control the dripping speed. If possible, you can also connect it to a computer for automatic operation.
It seems that only the 5th floor understands what I mean. In fact, in actual drip rate control, the liquid level in the burette is higher at the beginning. At that time, the center of gravity of the solution is higher, the potential energy is greater, and the drip rate is fast. As the height of the solution decreases, the drip rate gradually slows down! I am now using a complete set of infusion equipment from the hospital, and the effect is pretty good, because the liquid level changes less and can basically remain constant!
The author's method is indeed good, and I can try it in the future, but if the volume of the solution required is large, I will need to prepare several more saline bottles; in addition, if the required dripping speed is relatively high, the maximum dripping speed of the infusion device may not be enough. :lol :handshake This post was last edited by xwtsq on 2009-4-3 22:37 ]
I would like to ask: What are the main sources of errors in the determination of available sulfur?
Sorry, posted in the wrong place.