Weights, types empty

The vials, which are either prepared by the laboratory or obtained from a supplier, are certified precleaned autosampler vials with PTFE-lined septum caps and magnetic stir bars inside. The vials may contain 5 ml of analyte-free water or be empty. The vials with water may be unpreserved or be preserved with approximately 1 g of sodium bisulfate to pH < 2. (We need to select the type of the preservation, which is appropriate for the soil to be sampled.) The laboratory or the manufacturer will weigh the prepared vials with labels attached, record the weight on the label, and ship them to the field sampling team. 

Dredging is the use of a powered mechanism to remove unconsolidated material from a body of water. The mechanism is almost always a type of bucket or shovel. In the simplest case, it may be a metal bucket moved by chains or steel cables that arc attached to a pole. The bucket is dropped through the water and into the solid material on the bottom. As the bucket is retracted, its weight and trajectory force its leading edge into the solid material, and the bucket fills. When the bucket comes to the surface, it is emptied. This type of dredge is usually installed on the shore, near a body of water that covers a valuable mineral deposit. 

The term reaction rate denotes the rate of a reaction in a general way. We now define it specifically as the moles reacting per unit of reaction space per unit time. The reaction space can be the empty volume of the reacting space, void volume of the catalyst bed, volume of the catalyst, weight of the catalyst, surface area of the catalyst, or volume of one or all of the phases present in a heterogeneous system. Where time is concerned, its definition depends on the type of reactor used. There are essentially two broad classes of reactors batch and flow. In a batch reactor, time (0 corresponds to the elapsed time from the start of a run. In a flow reactor, it is given by... 

The actual pressure in a cylinder will depend upon the type of gas in the cylinder and the physical state of the contents. Cylinders containing gases which are gaseous at all pressures practicable for the cylinder, such as nitrogen or helium, will have a pressure which reflects the amount of material in the cylinder, while those that are in equilibrium with a liquid phase, such as ammonia, carbon dioxide, or propane, will be at the pressure of the vapor as long as any of the material remains in the liquid phase, provided that the critical temperature is not exceeded. The weight of the cylinder in excess of its empty weight is used to measure the amount of gas in the cylinder for the latter type of gas. 

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