Burette, volumetric flask, pipette, instrument calibration instruments, etc.
1, burette, used to measure the volume of titrant added volumetric instruments, it is a long, thin, uniform and fine scale glass tube, the lower end of the tip of the mouth, and there is a cut-off door to control the speed of the solution. According to the different construction of the cut-off door, can be divided into two types of acid and alkali.
2, volumetric flasks, used to prepare standard solutions or dilute solutions, is a measuring instrument. Will be full to the scale of the solution from the volumetric flask when pouring, because the wall of the bottle will be attached to the solution. Pour out the amount must be less than the volume shown, so quantitative transfer of solution should be used with a pipette and burette, not a volumetric flask.
3, pipette, pipetting, first use the earwash ball will be sucked to the solution above the standard line, with the index finger to block the upper mouth, and then adjust the solution of the lower edge of the meniscus so that it is tangent to the standard line, and then put the pipette into the acceptance of the container, so that the tip of the container to contact the container wall, the container is slightly slanting, the tube is upright, relax the forefinger, to be a free-flowing solution, after staying for 15 seconds to take out the pipette.
4, instrument calibration instrument, instrument scale is accurate, will directly affect the accuracy of volumetric analysis. Different levels of instruments allow different errors, for example, the first level of 25 ml pipette allows an error of ± 0.04 ml.
Expanded Information
Gauges in the process of use, do not and tools, cutting tools such as files, turning tools and drills, such as stacked together, so as not to touch the gauge. Do not just put on the machine tool to avoid the vibration of the machine tool and make the gauge fall down and damage. After use should be placed flat in a special box, so as not to deform the ruler. Gauge is a measuring tool, can never be used as a substitute for other tools, such as calipers to draw a line, with a steel ruler to clean up chips, etc. are wrong.
Temperature has a great impact on the measurement results, precision measurement of parts must make parts and gauges are measured at 20 degrees Celsius. Generally can be measured at room temperature, but must make the workpiece and gauge temperature consistent. Otherwise, due to the thermal expansion and contraction properties of metal materials, so that the measurement results are not accurate.
Baidu Encyclopedia-Precision Gauges
Baidu Encyclopedia-Volume Instruments