Basic Lab Techniques

What are the best practices while sharing a lab balance with other students? Select one or more:

- Brush off any chemical dust around the balance after each use. - Alert your TA or instructor about any issues with the balance.

When using the Tare function on a balance, start by ________. Then, ___________ to cancel out that mass. Finally, and record the mass of your sample.

1) placing the glassware on the balance 2) press the Tare/Zero button 3) add your sample to the glassware

Identify which balance was used to make each mass reading. 1) 0.90 g 2) 5.43 g 3) 6.539 g 4) 1.230 g 5) 4.0000 g

1) 0.01 2) 0.01 3) 0.001 4) 0.001 5) 0.0001

To measure out a volume of liquid, start by choosing the appropriate graduated cylinder and moving the bumper to the ______ of the graduated cylinder to protect it from breakage. Then, pour the liquid into the graduated cylinder until the _______ of the meniscus aligns with the desired volume marking when you look at the graduated cylinder from _______.

1) top 2) bottom 3) eye level

Determine whether each of the properties described applies to volumetric or graduated glassware. 1) Designed to measure one specific volume of liquid 2) Capable of measuring a range of volumes of liquid 3) Used for applications in which great accuracy is needed

1) volumetric 2) graduated 3) volumetric

What is the correct reading of the volume in the pictured buret? Make sure to report your reading with the appropriate significant figures.

17.32 mL

A graduated cylinder contains 10.00 mL water. A 14.74 g piece of aluminum is added to the water, and the volume rises to 15.46 mL. What is the density of the aluminum in g/mL?

2.7 g/mL

Suppose you are measuring the mass of a solid sample on a balance using a weigh boat. You record the data in a table. Mass of weigh boat3.738 gMass of weigh boat and sample 6.542 g What is the mass of the solid sample (in g)? Type answer:

2.804g

Suppose you are titrating an acid of unknown concentration with a standardized base. At the beginning of the titration, you read the base titrant volume as 1.08 mL. After running the titration and reaching the endpoint, you read the base titrant volume as 22.80 mL. What volume, in mL, of base was required for the titration?

21.72 mL

A 24.5 g sample of solution has a density of 0.768 g/mL. What is the sample volume (in mL)? Type answer:

31.9 mL

What practice will not help you make an accurate volume reading on a buret at the beginning of a titration? Select one:

Make sure that the meniscus starts exactly at 0.00 mL.