Liquid Density Liquid Density AnalysisAnalysis

By By Amanda StiffAmanda StiffCH EN 4903CH EN 4903

November 22, 2006November 22, 2006

OverviewOverview ObjectiveObjective Laboratory Equipment and Laboratory Equipment and

ProcedureProcedure– DensitometerDensitometer– PycnometerPycnometer

ResultsResults Conclusions and RecommendationsConclusions and Recommendations QuestionsQuestions

ObjectiveObjective

Identify the density of an Identify the density of an unknown salt solution using two unknown salt solution using two different methodsdifferent methods

DensitometryDensitometry PycnometryPycnometry

Determine which method is most Determine which method is most accurateaccurate

Equipment - Equipment - DensitometerDensitometer

Natural frequency or Natural frequency or period (T) of a hollow period (T) of a hollow U-tube is measured U-tube is measured to determine the to determine the density of a liquid or density of a liquid or gasgas

Constants A and B in Constants A and B in the equation are the equation are solved using density solved using density for water and air.for water and air.

BTA 2

BTA 2

Equipment - Densitometer Equipment - Densitometer (cont.)(cont.)

The unknown liquid was injected into The unknown liquid was injected into the densitometer and the period (T) the densitometer and the period (T) was read from the displaywas read from the display

Using the equation for the densitometer Using the equation for the densitometer the density of the liquid is foundthe density of the liquid is found

A 2 molar solution was run for A 2 molar solution was run for calibration purposescalibration purposes

Equipment - PycnometerEquipment - Pycnometer Pycnometers utilize the basic Pycnometers utilize the basic

equation for densityequation for density ρρ = mass/volume = mass/volume

The volume is knownThe volume is known

and the mass is weighedand the mass is weighed

on a scaleon a scale

Results - DensitometerResults - Densitometer

Densitometer @ 25.2oC

Constants Constants

A = A = 0.07060.0706 B = 18.3721B = 18.3721

Air Water 2 Molar Unknown

Period (T) 4.2884 5.7023 5.7948 5.7046

  4.2884 5.7022 5.7946 5.7047

  4.2884 5.7021 5.7947 5.7047

Average (T) 4.2884 5.7022 5.7947 5.7047

Density (g/cm3) 0.0013 0.9982 1.0733 1.0002

Results - PycnometerResults - Pycnometer

Pycnometer (10 ml)

EmptyWater (70oF) 2 Molar Unknown

Average Weight (g) 11.7815 21.9137 22.6935 21.9400

Average - Empty (g)   10.1322 10.9120 10.1585

Density (g/cm3)   1.0132 1.0912 1.0159

Density via SG (g/cm3) 0.9982 1.0750 1.0008

Results ComparisonResults Comparison

Densitometer results (95% CI)Densitometer results (95% CI) ρρ = 1.0002 +/- 0.0004 g/cm = 1.0002 +/- 0.0004 g/cm33

Pycnometer results (95% CI)Pycnometer results (95% CI) ρρ = 1.0008 +/- 0.014 g/cm = 1.0008 +/- 0.014 g/cm33

Conclusions and Conclusions and RecommendationsRecommendations

Densitometer was the more accurate Densitometer was the more accurate methodmethod

Pycnometry is a much easier methodPycnometry is a much easier method

Know what kind of liquid you put into Know what kind of liquid you put into the densitometerthe densitometer

Happy ThanksgivingHappy Thanksgiving

References and References and AcknowledgementsAcknowledgements

CRC Handbook of Chemistry and Physics.CRC Handbook of Chemistry and Physics. 48th 48th ed. Ohio: Chemical Rubber Co., 1967-68ed. Ohio: Chemical Rubber Co., 1967-68

National Institute of Standards and National Institute of Standards and Technology. Technology. Retrieved August 30, 2006, from Retrieved August 30, 2006, from www.nist.gov/srd/pdf%20files/jpcrd196.pdf, www.nist.gov/srd/pdf%20files/jpcrd196.pdf, Page 29Page 29

Thanks to my lab partner Randy PummillThanks to my lab partner Randy Pummill

Questions?Questions?