Which of the following images shows a buret?
The question asks us to identify the image showing a buret. Each piece of glassware has a distinctive shape and structure. Burets are cylindrical pieces of glassware with multiple graduations and a valve or stopcock at the bottom. The stopcock or tap can be opened or closed to adjust the amount of liquid released into another vessel. (A) looks like our answer because it is cylindrical. It has multiple graduations and a stopcock at the bottom. Let’s confirm that (A) is our answer.
There are a variety of labware that can be used to measure liquids in the laboratory. Some glassware can be used to measure and deliver only one specific volume of liquid. Others can measure variable volumes. Pipets and volumetric flasks have only one graduation or volume marking. This is shown in answer option (D), which is a pipet. Liquids are measured and drawn up to the mark by suction using a pipet pump.
In a buret, liquids are poured into the top of the vessel and released at the bottom using the valve or stopcock. Glassware that can measure variable volumes include burets, syringes, graduated cylinders, beakers, and many more. We can see the multiple volume graduations on the buret as well as on the apparatus in (B) and in (C). So (A), (B), and (C) measure variable volumes.
Apparatus (B) and (C) are both cylindrical in shape, just like apparatus (A), whereas the pipet has this widened portion in the middle. In (B), liquids are poured into the top of the vessel and the desired amount poured out the top of the vessel. (B) also has a flat base on which it can stand. (B) is called a graduated or measuring cylinder.
In apparatus (C), liquids are drawn in by suction, by pulling back the plunger, and are released by depressing the plunger. This apparatus is called a syringe, and it may have a needle on the end.
Graduated cylinders, syringes, and pipets are all handheld during operation, while burets must be clamped upright during operation. We have seen that all four pieces of glassware have some similarities and they all measure liquids but that because of these combined reasons and perhaps most notably this stopcock, the image that shows a buret is answer option (A).