Water turn-over/ mixing

A lake mixes on some time scale so it might be modeled as a stirred reactor for times longer than the mixing time, and it is a tubular reactor for shorter times. Most lakes turn over seasonally because of the density rrtirtimum of water at 4°C so they are mixed on at least a 1 year time scale. Small lakes are mixed effectively by wind on shorter time scales. Deep lakes exhibit an upper layer that turns over and mixes and a lower layer that does not. The inlets to a lake are aU the rivers that flow into it and also water coming from rainfall, and the outlets are aU the rivers that flow out of it and evaporatiorr... 

The potter shown in Figure 1 uses water to help sculpt the sides of a clay pot. As he dips his clay-covered fingers into a container of water, the water turns brown. The clay-water mixture appears uniform. However, if the container sits overnight, the potter will see a layer of mud on the bottom and clear water on top. The clay does not dissolve in water. The clay breaks up into small pieces that are of such low mass that, for a while, they remain suspended in the water. This type of mixture, in which the different parts spontaneously separate over time, is called a suspension. In a suspension, the particles may remain mixed with the liquid while the liquid is being stirred, but later they settle to the bottom. 

To put out the fire, a man threw a shovelful of wet scale into the bucket. The water became mixed with the oil, turned to steam, and blew the oil over the man, who was standing 1-2 m away. He died from his burns. 

If the nurse is responsible for administering the medication by nebulization, it is important to place the patient in a location where he can sit comfortably for 10 to 15 minutes. The compressor is plugged in and the medication mixed as directed, or the prepared unit dose vial is emptied into the nebulizer. Different types of medication are not mixed without checking with the physician or the pharmacist. The mask or mouthpiece is assembled and the tubing connected to the compressor. The patient is placed in a comfortable, upright position with the mask over the nose and mouth. The mask must fit properly so that the mist does not flow up into the eyes. If using a mouthpiece instead of a mask, have the patient place the mouthpiece into the mouth. The compressor is turned on and the patient instructed to take slow, deep breaths. If possible, the patient should hold his breath for 10 seconds before slowly exhaling. The treatment is continued until the medication chamber is empty. After treatment, the mask is washed with hot, soapy water, rinsed well, and allowed to air dry. 

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