# Lab #1: Density Determinations for Solutions

Jessa Arellano

September 19, 2014

Period 4

Lab #1: Density Determinations for Solutions

Theory:

The density of a sample of matter is very useful when trying to find the identity of an unknown substance. The units of density are quoted in (g/mL) for liquid samples of matter. For that reason if the volume is known of a liquid, determining its density is easily determined by weighing it accurately. Density can also be used as a tool for finding the concentration of solutions in some cases. The density is different in a substance when a substance is added to a pure liquid to when both the solute and solvent were separate all together. There are many ways to determine density. This method determined the density of a liquid by weighing a volume in a graduated cylinder. With the volume in milliliters and the mass in grams, density of an unknown substance can be found by using this method. Purpose:

The purpose of this experiment is to find the concentrations of 2 unknown substances. Procedures:

1.) Determine the density of solutions known and unknown concentrations. 2.) Make a mass determination for 10.00 mL of each known and unknown solution, using a balance and a graduated cylinder. Record. 3.) Organize data using a table, and construct a graph of the density of your solutions of known concentration versus the percentage of NaCl the solution contains. 4.) Use the graph to determine the concentration of NaCl in the solutions of unknown concentration. Data and Results:

Solutions

5%

10%

15%

20%

25%

Unknown #1

Unknown #2

Temperature

20.0 ̊̊ C

20.0 ̊̊ C

20.0 ̊̊ C

20.0 ̊̊ C

20.0 ̊̊ C

20.0 ̊̊ C

20.0 ̊̊ C

Mass (g)

10g

10.5 g

11.0 g

11.2g

11.8 g

10.6 g

10.8 g

Volume(mL)

9.9 mL

9.9 mL

10.0 g

9.80 mL

9.90 mL

9.9 mL

10.0 mL

Density(g/mL)

1.0g/mL

1.06g/mL

1.10g/mL

1.14g/mL

1.19g/mL

1.07g/mL

1.08g/mL

Conc. Of unknown #1

Conc. Of unknown #2

Slope of line

y-intercept

r

r^2

Excell

12%

13%

.0088...

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