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Density is a substance's mass per unit of volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume:
Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.
Titration is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte. A reagent, termed the titrant or titrator, is prepared as a standard solution of known concentration and volume. The titrant reacts with a solution of analyte to determine the analyte's concentration. The volume of titrant that reacted with the analyte is termed the titration volume.
Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units or by various imperial or US customary units. The definition of length (cubed) is interrelated with volume. The volume of a container is generally understood to be the capacity of the container; i.e., the amount of fluid that the container could hold, rather than the amount of space the container itself displaces. By metonymy, the term "volume" sometimes is used to refer to the corresponding region.
Laboratory glassware refers to a variety of equipment used in scientific work, and traditionally made of glass. Glass can be blown, bent, cut, molded, and formed into many sizes and shapes, and is therefore common in chemistry, biology, and analytical laboratories. Many laboratories have training programs to demonstrate how glassware is used and to alert first–time users to the safety hazards involved with using glassware.
The volumetric heat capacity of a material is the heat capacity of a sample of the substance divided by the volume of the sample. It is the amount of energy that must be added, in the form of heat, to one unit of volume of the material in order to cause an increase of one unit in its temperature. The SI unit of volumetric heat capacity is joule per kelvin per cubic meter, J⋅K−1⋅m−3.
In recipes, quantities of ingredients may be specified by mass, by volume, or by count.
A burette is a graduated glass tube with a tap at one end, for delivering known volumes of a liquid, especially in titrations. It is a long, graduated glass tube, with a stopcock at its lower end and a tapered capillary tube at the stopcock's outlet. The flow of liquid from the tube to the burette tip is controlled by the stopcock valve.
A pipette is a type of laboratory tool commonly used in chemistry and biology to transport a measured volume of liquid, often as a media dispenser. Pipettes come in several designs for various purposes with differing levels of accuracy and precision, from single piece glass pipettes to more complex adjustable or electronic pipettes. Many pipette types work by creating a partial vacuum above the liquid-holding chamber and selectively releasing this vacuum to draw up and dispense liquid. Measurement accuracy varies greatly depending on the instrument.
A graduated cylinder, also known as a measuring cylinder or mixing cylinder, is a common piece of laboratory equipment used to measure the volume of a liquid. It has a narrow cylindrical shape. Each marked line on the graduated cylinder represents the amount of liquid that has been measured.
Flow measurement is the quantification of bulk fluid movement. Flow can be measured using devices called flowmeters in various ways. The common types of flowmeters with industrial applications are listed below:
The drop is an approximated unit of measure of volume, the amount dispensed as one drop from a dropper or drip chamber. It is often used in giving quantities of liquid drugs to patients, and occasionally in cooking and in organic synthesis. The abbreviations gt or gtt come from the Latin noun gutta ("drop").
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
In analytical chemistry, a standard solution is a solution containing an accurately known concentration. Standard solutions are generally prepared by dissolving a solute of known mass into a solvent to a precise volume, or by diluting a solution of known concentration with more solvent.
Baker's percentage is a notation method indicating the proportion of an ingredient relative to the flour used in a recipe when making breads, cakes, muffins, and other baked goods. It is also referred to as baker's math, and may be indicated by a phrase such as based on flour weight. It is sometimes called formula percentage, a phrase that refers to the sum of a set of baker's percentages. Baker's percentage expresses a ratio in percentages of each ingredient's weight to the total flour weight:
An eye dropper, also called Pasteur pipette or simply dropper, is a device used to transfer small quantities of liquids. They are used in the laboratory and also to dispense small amounts of liquid medicines. A very common use was to dispense eye drops into the eye. The commonly recognized form is a glass tube tapered to a narrow point and fitted with a rubber bulb at the top, although many styles of both plastic and glass droppers exist. The combination of the pipette and rubber bulb has also been referred to as a teat pipette. The Pasteur pipette name is from the French scientist Louis Pasteur, who used a variant of them extensively during his research. In the past, there was no equipment to transfer a chemical solution without exposing it to the external environment. The hygiene and purity of chemical compounds is necessary for the expected result of each experiment. The eye dropper, both glass and plastic types, can be sterilized and plugged with a rubber bulb at the open end of the pipette preventing any contamination from the atmosphere. Generally, they are considered cheap enough to be disposable, however, so long as the glass point is not chipped, the eye dropper may be washed and reused indefinitely.
A volumetric pipette, bulb pipette, or belly pipette allows extremely accurate measurement of the volume of a solution. It is calibrated to deliver accurately a fixed volume of liquid.
Piston-driven air displacement pipettes are a type of micropipette, which are tools to handle volumes of liquid in the microliter scale. They are more commonly used in biology and biochemistry, and less commonly in chemistry; the equipment is susceptible to damage from many organic solvents.
A graduated pipette is a pipette with its volume, in increments, marked along the tube. It is used to accurately measure and transfer a volume of liquid from one container to another. It is made from plastic or glass tubes and has a tapered tip. Along the body of the tube are graduation markings indicating volume from the tip to that point. A small pipette allows for more precise measurement of fluids; a larger pipette can be used to measure volumes when the accuracy of the measurement is less critical. Accordingly, pipettes vary in volume, with most measuring between 0 and 25.0 millilitres.
A media dispenser or a culture media dispenser is a device for repeatedly delivering small fixed volumes of liquid such as a laboratory growth medium like molten agar or caustic or volatile solvents like toluene into a series of receptacles. It is often important that such dispensers operate without biological or chemical contamination, and so must be internally sealed from the environment and designed for easy cleaning and sterilization before use. At a minimum, a media dispenser consists of some kind of pump connected to a length of discharge tubing or a spout. Dispensers used in laboratories are also frequently connected to microcontrollers to regulate the speed and volume of the medium as it leaves the pump.
References
- ↑ Robert Bruce Thompson (2008), Illustrated guide to home chemistry experiments: all lab, no lecture, O'Reilly Media, p. 24, ISBN 978-0-596-51492-1 , retrieved 2011-04-02
- ↑ Water quality - Google Books, Water Supply Operations Training Series (3 ed.), American Water Works Association, 2003, p. 75, ISBN 978-1-58321-232-5 , retrieved 2011-04-02
- ↑ Mukherjee (2001). Med Lab.Technology. Vol. 1. Tata McGraw-Hill Education. p. 67. ISBN 978-0-07-463260-4 . Retrieved 2011-04-02.
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