Dilution Quiz CH 202

Which of the following practices are important to achieve a quantitative transfer when adding a solid to a volumetric flask? A) Gently tap on the paper funnel so that no solid is left clinging to it B) Make sure that no solid is spilled when pouring it from the weighing beaker through the paper funnel C) Rinse the weighing beaker with deionized water or the solvent being used, and add it to the volumetric flask D) Rinse the weighing beaker with deionized water or the solvent being used, and dispose of it in the waste bottle E) Rinse the paper funnel with deionized water or the solvent being used into the volumetric flask

A) Gently tap on the paper funnel so that no solid is left clinging to it B) Make sure that no solid is spilled when pouring it from the weighing beaker through the paper funnel C) Rinse the weighing beaker with deionized water or the solvent being used, and add it to the volumetric flask

Before using a pipet, it should first be conditioned. Please select the step or steps that are involved in properly conditioning a pipet. A) Pour some reagent into a beaker for use with the pipet B) Pipet directly from the reagent bottle C) Draw enough reagent into the pipet to fill it above the etched mark so that all of the walls are coated with reagent D) Drain the reagent back into your beaker so it can be used again E) Draw a small volume of reagent into the pipet, turn it sideways and rotate so all the walls are coated with reagent F) Dispose of the reagent into a waste beaker since it is now contaminated with whatever may have been on the pipet

A) Pour some reagent into a beaker for use with the pipet E) Draw a small volume of reagent into the pipet, turn it sideways and rotate so all the walls are coated with reagent F) Dispose of the reagent into a waste beaker since it is now contaminated with whatever may have been on the pipet

When using a bulb with a pipet, which of the following are true? A) The bulb should be held just firmly enough to the end of the pipet to make a seal B) Once there is solution in the pipet, pressure should be applied to the bulb until the solution is at the desired level C) The bulb should be jammed onto the end of the pipet so that the pipet can be carried by the bulb D) Solution should be drawn up into the entire pipet and bulb E) Once there is solution in the pipet, the bulb should be replaced with a thumb or index finger so liquid can be slowly released into the desired level F) Solution should be drawn up only slightly above the calibration mark

A) The bulb should be held just firmly enough to the end of the pipet to make a seal E) Once there is solution in the pipet, the bulb should be replaced with a thumb or index finger so liquid can be slowly released into the desired level F) Solution should be drawn up only slightly above the calibration mark

If you significantly overshoot your target weight on an analytical balance, which of the following actions are correct? A) The excess material should be considered waste and disposed of properly B) The excess material should be returned to the reagent jar C) You should use the spatula provided to remove excess material D) The excess material should be kept on weighing paper and used for the next sample that must be prepared E) You should lift up the beaker, and gently tap it to pour the excess material back into the reagent jar

A) The excess material should be considered waste and disposed of properly C) You should use the spatula provided to remove excess material

Regarding the solution that remains in a pipet after gravity has drained it, which of the following are true? A) The remaining solution in a serological pipet should be gently expelled with a pipet bulb to complete the transfer B) The remaining solution in a serological pipet should NOT be gently expelled with a pipet bulb to complete the transfer C) The remaining solution in a volumetric pipet should be gently expelled with a pipet bulb to complete the transfer D) The remaining solution in a volumetric pipet should NOT be gently expelled with a pipet bulb to complete the transfer

A) The remaining solution in a serological pipet should be gently expelled with a pipet bulb to complete the transfer D) The remaining solution in a volumetric pipet should NOT be gently expelled with a pipet bulb to complete the transfer

In the video entitled "Pipeting Techniques", Lindsey demonstrates the proper use of which of the following? A) Volumetric pipets B) Mohr pipets C) Volumetric flasks D) Serological pipets E) Burets F) Measuring pipets

A) Volumetric pipets D) Serological pipets

In the video entitled "Using an analytical balance", Lindsey demonstrates weighing a solid into what on an analytical balance? A) A small beaker, half-filled with solvent B) An empty, clean and dry beaker C) A piece of carefully folded paper D) An empty, clean and dry Erlenmeyer flask E) A volumetric flask

B) An empty, clean and dry beaker

When reading the meniscus of a volumetric flask, which of the following are acceptable? A) View the etched line on the volumetric flask above your eye level B) Bend down to view the etched line on the volumetric flask at eye level C) View the etched line on the volumetric flask at eye level D) View the etched line on the volumetric flask below your eye level E) It does not matter where the etched line is on the volumetric flask in relation to your eye level

B) Bend down to view the etched line on the volumetric flask at eye level C) View the etched line on the volumetric flask at eye level

When using a volumetric flask, which of the following are true? A) If any solute is lost in transfer, the concentration of the resulting solution will be higher than the calculated value B) If a volumetric flask is over-filled so that the bottom of the meniscus is above the etched calibration mark, the concentration of the resulting solution will be lower than the calculated value C) If a volumetric flask is filled so that the top of the meniscus is level with the etched calibration mark, the concentration of the resulting solution will be higher than the calculated value D) If any solute is lost in transfer, the concentration of the resulting solution will be lower than the calculated value E) If the solid is added to a volumetric flask after filling it with solvent, the concentration of the resulting solution will be higher than the calculated value F) If the solid is added to a volumetric flask after filling it with solvent, the concentration of the resulting solution will be lower than the calculated value G) If a volumetric flask is over-filled so that the bottom of the meniscus is above the etched calibration mark, the concentration of the resulting solution will be higher than the calculated value H) If a volumetric flask is filled so that the top of the meniscus is level with the etched calibration mark, the concentration of the resulting solution will be lower than the calculated value

B) If a volumetric flask is over-filled so that the bottom of the meniscus is above the etched calibration mark, the concentration of the resulting solution will be lower than the calculated value C) If a volumetric flask is filled so that the top of the meniscus is level with the etched calibration mark, the concentration of the resulting solution will be higher than the calculated value D) If any solute is lost in transfer, the concentration of the resulting solution will be lower than the calculated value F) If the solid is added to a volumetric flask after filling it with solvent, the concentration of the resulting solution will be lower than the calculated value

How accurate are the volumes measured with a serological pipet? A) 1 mL B) 0.1 mL C) 0.01 mL D) 0.001 mL

C) 0.01 mL

When a student was weighing out a sample, the balance display read "0.500 g." Which of the following is the correct way to record this value into a lab notebook? A) 0.5 g B) 0.50 g C) 0.500 g D) 0.5000 g E) ~0.5 g

C) 0.500 g

After transferring all of the solid from a weighing beaker into a volumetric flask, which of the following describes the step or steps to finish making the solution? A) Once the solid is dissolved, fill the volumetric flask almost to the etched line and finish adding solvent dropwise until the TOP of the meniscus is touching the etched line B) Fill the volumetric flask all the way to the etched line, stopper it and invert a few times to ensure complete mixing and that the solid is completely dissolved C) Once the solid is dissolved, fill the volumetric flask almost to the etched line and finish adding solvent dropwise until the BOTTOM of the meniscus is touching the etched line D) Fill the volumetric flask with a significant volume anywhere from about halfway to where the neck narrows. Stopper the flask and invert a few times to ensure complete mixing and that the solid is completely dissolved

C) Once the solid is dissolved, fill the volumetric flask almost to the etched line and finish adding solvent dropwise until the BOTTOM of the meniscus is touching the etched line D) Fill the volumetric flask with a significant volume anywhere from about halfway to where the neck narrows. Stopper the flask and invert a few times to ensure complete mixing and that the solid is completely dissolved

Once the reading on the analytical balance stops fluctuating, which of the following are true? A) You should ask your lab partner to record it in their lab notebook B) You should memorize it so you can write it in your lab notebook later C) You should record the mass in your lab notebook with a pen D) You should record the mass on a piece of scrap paper to be transferred into your lab notebook later

C) You should record the mass in your lab notebook with a pen

In the video entitled "Using an analytical balance", what does Lindsey recommend you use to clean the weighing pan before and after use? A) Your hands after putting on rubber gloves B) The sleeve of your shirt C) A strong puff of air from your lungs D) A piece of weighing paper E) The brush that is provided F) A cloth that has been provided

E) The brush that is provided