Does Hobby Lobby sell pipettes?
Does Hobby Lobby sell pipettes?
Boasting a plastic construction with a classic dropper design, these pipettes offer a variety of volume capacities that can be used for diluting and mixing different amounts of paints for plastic models and other crafts. Mix, paint, and harness your creativity! Check your local store for availability.
What is a plastic pipette?
Pasteur pipettes are plastic or glass pipettes used to transfer small amounts of liquids, but are not graduated calibrated for any particular volume. The bulb is separate from the pipette body. Pasteur pipettes are also called teat pipettes, droppers, eye droppers and chemical droppers.
Why use a pipette instead of a measuring cylinder?
Why use a pipette instead of a measuring cylinder? Unlike a measuring cylinder, a pipette will be more accurate with all of the sample, accounting for every drop of the substance being held within the tool.
Why is a burette more accurate?
Burettes are larger than a pipette, it has a stopcock at the bottom to control the release of liquid. Burette is similar like graduated cylinder and is easier to measure a required volume of liquid through graduations. But, it has large meniscus and hence its accuracy and precision is less in measuring liquids.
How can you tell if a pipette is dirty?
One sure sign that glassware is dirty is the formation of water droplets on the inside wall of the glassware. If after cleaning with soap, water and a brush, water droplets form you probably did not clean the glassware well enough and should repeat the washing until no droplets form when rinsed with distilled water.
What is the largest source of pipetting problems?
Human error is the largest source of pipetting problems, followed by liquids sticking to the tips, and loss of accuracy when working with viscous liquids (multi-option select question, chart depicts the percent of survey respondents who experienced these various pipetting errors).
How do you Sterilise pipettes?
Open the pipette, immerse the parts in a detergent solution, such as Deconex® 12 Basic. Rinse well with distilled water and allow to dry. DNA can be eliminated by immersing pipette parts in at least 3% (w/v) sodium hypochlorite for at least 15 minutes (2,3). Rinse well with distilled water and allow to dry.
Why are burette upside down?
Because you want to know how much has been used rather than knowing how much there are.
How accurate is a burette?
10 mL burettes are usually graduated each 0.05 mL, while 25 mL and 50 mL burettes are usually graduated each 0.1 mL. That means that 50 mL burettes have the highest resolution. 0.050 mL out of 50 mL is 0.1%, and that’s about maximum precision that we can get from volume measurement when using burette.
Why do you read the top of the meniscus and not the bottom as with most titrations?
Your eye must be level with the meniscus to avoid parallax error. If viewed from above, the reading will appear lower, whereas, if viewed from below, it will appear higher. For our burets with a 0.1 mL graduation you should read to ±0.05 mL.
Do you read from the top of the meniscus?
The key to getting an accurate reading, is to measure the center of the meniscus whether it be concave or convex. E.g. with a concave meniscus, measure the bottom of the meniscus and for convex meniscus, take the reading from the top of the meniscus.
What is a meniscus on a graduated cylinder?
Place the graduated cylinder on a flat surface and view the height of the liquid in the cylinder with your eyes directly level with the liquid. The liquid will tend to curve downward. This curve is called the meniscus. Always read the measurement at the bottom of the meniscus.
What is a meniscus level?
A meniscus is a curve in the surface of a molecular substance (water, of course) when it touches another material. With water, you can think of it as when water sticks to the inside of a glass.
At what level should your eye be located when reading a volume correctly?
Your eye must be on the same level as the bottom of the meniscus to read the volume correctly. The meniscus formed by a non-wetting liquid, such as mercury (Hg), is convex with the highest point in the center. In the case of a convex meniscus, the highest point is used to make the reading.
What are the two main things to remember when reading a graduated cylinder?
To correctly read a graduated cylinder, the surface at the center of the meniscus must be read, not the top of the ring of liquid clinging to the wall of the graduated cylinder. For most liquids, this “center” will be the lowest point of the meniscus.
How does the meniscus affect reading the correct volume?
A meniscus occurs because of surface tension in the liquid and must be read at eye level. For a concave meniscus, the correct volume will be read at the bottom of the curve. For a convex meniscus, the opposite is true and the correct reading will be at the top of the curve.
Why should volumetric glassware never be washed in hot water or dried in hot ovens?
You must never expose any volumetric glassware to sources of heat since such exposure will adversely affect the calibration. Thus, you must never dry any volumetric glassware in a drying oven.
Why are Volumetric pipettes more accurate?
Volumetric pipets are so accurate because the long neck decreases the error in measuring volume of the meniscus. Graduated cylinders are designed for accurate measurements of liquids with a much smaller error than beakers.
Why is drying the interior surface of glassware before use not really necessary?
It is seldom necessary to dry glassware before use; in fact this practice should be discouraged because it wastes time, can be a cause of contamination and result in changes in volumetric glassware. Always pre-rinse burets and volumetric pipettes with the titrant or solution to be transferred prior to use.
Why do Volumetric Flasks not need to be dry?
The volumetric flask must be clean and dry because it is used to prepare the solution so you do not want to contaminate your chemicals and get a wrong reading. If it is wet with the solution it does not matter.
Why is it unnecessary to dry the Erlenmeyer flask?
Why don’t we dry it? This is because since the volume and the concentration of the acid is known. The number of moles added is known to us and this number doesn’t change regardless of how much water is in the flask.
Why is the conical flask only rinsed with distilled water?
It reduces the chance of solution splashing out whilst swirling. During a titration, a chemist rinsed the inside of the conical flask with deionised water. To make sure all the acid/alkali is at the bottom of the conical flask and can react, because as you swirl the acid/alkali can travel up the sides of the flask.
Why do we use a burette?
The burette is used to measure the volume of a dispensed substance, but is different from a measuring cylinder as its graduations measure from top to bottom. The precision and control of the burette over other means of adding solution is beneficial for use in titration.