# Laboratory Techniques and Measurements

Topics: Water, Density, Volume Pages: 2 (412 words) Published: February 12, 2013
A. Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason?

The reason why water did not boil at 100°C could be because we are not at sea level; the pressure could be lower.

B. While heating two different samples of water at sea level, one boils at 102°C and one boils at 99.2°C. Calculate the percent error for each sample from the theoretical 100.0°C.

1st sample 1.96% error

2nd sample 0.81% error

C. An unknown, rectangular substance measures 3.6 cm high, 4.21 cm long, and 1.17 cm wide. If the mass is 21.3 g, what is this substance’s density (in grams per milliliter)?

1.20 g/ml

D. A sample of gold (Au) has a mass of 26.15 g. Given that the theoretical density is 19.30 g/mL, what is the volume of the gold sample?

1.355 ml^3

E. What would happen if you dropped the object into the beaker while using the Archimedes’ Principle method instead of submerging the object?

If the object was dropped into the beaker, then the measurements would not be correct.

F. How did the magnet’s density measurement using the Archimedes’ Principle compare to the density measurement using the calculated volume? Which method might be more accurate? Why?

The calculated volume measurement is more accurate because Archimedes’ Principle might have a higher percentage of error.

G. You are given a small piece of gold colored material and want to determine if it is actually gold. Using the Archimedes’ Principle you find that the volume is 0.40 cm3 and the mass is 6.0 g. What conclusions can you reach from your simple density analysis?

Density: 15 g/cm^3

It is not gold or pure gold because the gold’s density is 19.3 g/cm^3.

H. How would you prepare 10 mL of a 0.25M HCl solution if 1M HCl was available? How much 1M HCl is needed? How much distilled water is used?

0.25M is 0.25 moles/L

0.25*10/1= 2.5 mL needed

I.From the...