Which of the following things should always do before running the centrifuge?

Before running the centrifuge:

Operate centrifuges only in designated research space to ensure adequate ventilation. Use metal or plastic tubes (other than nitrocellulose) whenever possible. Check tubes for breaks before each use. Inspect the inside of the cups for rough walls caused by erosion.

What is the purpose of a centrifuge?

What does a centrifuge do? The purpose of a centrifuge is to take advantage of the principles above, and use them to separate liquids from solids (or lighter liquids from denser liquids). In essence, it does what gravity would naturally do, but much faster. Think about a bottle of fresh-squeezed orange juice.

Why do we use centrifuge?

A centrifuge is used to separate particles suspended in a liquid according to particle size and density, viscosity of the medium, and rotor speed.

When the centrifuge process is complete students should do which of the following?

Centrifuge for approximately 30 seconds. When the centrifuge process is complete, students should do which of the following? Using the eyehole on top, monitor the spinning rate and open the lid only after the rotor has slowed significantly.

What are the safety rules when using a centrifuge in separation of precipitates from solutions?

Separation of Precipitates from Solutions

Always lower the centrifuge cover before turning it on (if a tube breaks, those nearby won’t be hit by flying glass). Allow the centrifuge to coast to a stop. Do not attempt to slow it with your fingers.

Why is it important not to stop the centrifuge abruptly?

This can result in injury AND it will stir up the solution you were attempting to separate by centrifugation. Wait for the rotor to come to a complete stop before attempting to remove your test tubes. After about 30 seconds of centrifugation most precipitates will have settled.

What should be done to waste solutions containing copper ion?

It should be dumped in a beaker labeled “waste copper” on one’s bench during the experiment. It should be disposed of in the bottle for waste copper ion when work is completed.

Why should you never invert a volumetric flask until you have finished filling it with solvent to the calibration mark line?

The volume of a volumetric flask is the volume of a liquid in the flask which is filled up to the marked line. … Because the volume may change at mixing of a sample and a solvent, the sample should not be diluted directly to the marked line without stopping.

Which of the following glassware needs to be conditioned prior to use?

Just before use, a buret should be “conditioned” to ensure that any water adhering to the inside walls is removed.

What does a volumetric flask measure?

A volumetric flask (measuring flask or graduated flask) is a piece of laboratory apparatus, a type of laboratory flask, calibrated to contain a precise volume at a certain temperature. … The marking indicates the volume of liquid contained when filled up to that point.

When using a volumetric flask Why do we have to fill it exactly on the given mark?

A volumetric flask has a large round bottom with only one graduation mark positioned on the long narrow neck. The position of the mark facilitates the accurate and precise reading of the meniscus.

Why do you invert the flask a few times after diluting to the mark?

After the solute dissolves, the volume of the solution will be slightly greater than a liter because the hydrated sodium and chloride ions take up space in the solution. Instead, a volumetric flask needs to be used. … The flask is capped and inverted several times to completely mix.

Why must all the remaining solution be transferred into the volumetric flask?

why must all the remaining solutions need to be transferred into the volumetric flask? Transferring solutions without fully dissolving the solute will result in an inaccurate concentration.

Why do we use a volumetric flask quizlet?

A volumetric flask is used to measure precise liquids when you make a Molar solution.

When filling a volumetric flask fill it so the bottom of the?

meniscus
The curved surface of the liquid is called the meniscus. When filling a volumetric pipette or flask, make sure that the bottom of the meniscus is exactly even with the calibration mark. 2.

Why it is necessary for a laboratory glassware be calibrated?

Volumetric glassware calibration is essential to ensure accurate results in all laboratory settings. Calibration takes place before glassware is put into circulation for use, and there are also recommended timeframes to conduct calibration on older glassware.

Is it important to prepare solutions at room temperature when using a volumetric flask?

If you’re trying to be precise when making your solutions, the more important thing (in my opinion) is to make sure all the components of your solution, including water, are at room temperature (technically 20 degrees C) when you make the solution up.