Question

Lab Report Guide:

-          1. Results (4 pts)

o   Tables neatly filled out with data

o   Proper significant figures

o   Legible sample calculations

-          2. Error Analysis (4 pts)

o   Determination of percent error (for glassware and metal densities)

o   Typed discussion of measured results vs literature results and description of possible sources of error. Note that “human error” is not an acceptable answer. Please be specific.

-          3. Post Lab Questions (4 pts)

o   Hand written answers to the Post Lab questions. Note that single sentence answers will not suffice and if I cannot read your handwriting I cannot grade it. State the answer to the question followed by a brief description of the evidence supporting that answer.

Post Lab Questions:

Which Piece of Glassware (100 mL beaker, a 10 mL graduated cylinder or the 100/50 mL graduated cylinder) is most accurate according to your results? Explain why you came to this conclusion. Do your results match the expect results?

If you were asked to measure out 86.0 mL water, which piece of glassware would you choose and why?

Would this technique work to measure materials with densities less than 1.00 g/mL? Explain why or why not.

Metals with greater atomic number often have higher density. Why do you think this is?

Data 1A: (Please fill out this table and submit with the lab report. Recopy if messy)

For each piece of glassware, calculate the mass of the water added, then use the density of water (0.998 g/mL) to find the calculated volume of the water. Record your three volume calculations below. Be sure to that all measurement include the correct number of significant figures and appropriate units.

	100 mL beaker	10 mL grad. cyl.	100/50 mL grad. cyl.
Dry Mass	59.548g	38.640g	87.003g
Dry Mass of container + H2O	72.199g	48.548g	95.905g
Mass of H2O (subtract the masses)	12.651g	9.908g	8.902g
CalculatedVolume (from mass of H2O)	12.670mL	9.928mL	8.920mL

Sample Calculations: (Show a sample of each type of calculation you did)

Data 1B: (Please fill out this table and submit with the lab report. Recopy if messy)

	Metal A	Metal B	Metal C	Metal D	Metal E
Mass of metal(g)	77.077g	5.417g	22.704g	15.174g	13.655g
Initial Volume of Water	10.1mL	10.3mL	10.5mL	9.9mL	10.2mL
Volume of water + metal (mL)	12.2mL	12.1mL	12.3mL	11.8mL	12.3mL
Volume of metal (mL) (subract volumes)	2.2mL	1.8mL	1.8mL	1.9mL	2.1mL
Density of metal (g/mL)	8.1g/mL	3.0g/mL	13g/mL	8.0g/mL	6.5g/mL
Identity of metal	Cu	Al	Pb	Fe	Zn

Sample Calculations: (Show a sample of each type of calculation you did)

And please check my significant figures for the table

Answer 1

10 mL graduated cylinder is most accurate and 100 mL beaker is least accurate.
In the 10 mL graduated cylinder, the least count is 0.5 mL.
In 100/50 mL graduated cylinder, the least count is 1 mL
In 100 mL beaker the least count is 25 mL.

86.0 mL of water will be measured by using 100 mL graduated cylinder. This is because the volume to be measured and the maximum volume of the 100 mL graduated cylinder do not differ significantly.
Also remember that 100 mL graduated cylinder is more accurate than 100 mL beaker.

Yes, this technique will work to measure materials with densities less than 1.00 g/mL. This is because we are measuring the volume and are not concerned about the mass or density.

Metals with greater atomic number often have higher density. Higher atomic number means higher mass.
Also when there are plenty of inner electrons with poor shielding effect. This results in higher effective nuclear charge and lower atomic volume.
Thus, the atomic mass is higher and the atomic volume is lower. Hence, the density is higher.