# Chem LAB rEPORT LAB 2

BioL121

9/16/14

Density and Making Solutions

Objective and Background/ Theory of Experiment:

The objective of the experiment was to determine the density of a metal along with the density of distilled water. In an attempt to help the experimenters more thoroughly understand the relationship between concentration and density. Archimedes a Greek mathematician in the third century B.C. originally determined the relationship between the amount of matter that is within a particular space. He used this knowledge to determine if a crown made for the King was in fact made of pure gold, which as happens was not. He discovered such knowledge when he realized that the volume of an object could be determined by the displacement of the liquid. Density is a property that will be consistent for any substance. For pure substances it is the same concept as concentration. For solutions of material density increases as the concentration increases. Many substances can be found by density alone, and concentration can be identified if the density is known. In this experiment, the experimenters found the density of solid objects and then the concentrations of solutions based on their densities. It was determined that as density increases, concentration does as well. The density of a substance is something that stays constant, for solutions of material the density is expected to increase in direct translation to the concentration increasing. The theory surrounding this lab was to see in practice how density could be determined with displacement and then to determine whether the density does in fact increase directly with the concentration.

Summary of Key Data

Figure 1: From Part 1

Mass of Brass

13.2200g

Initial Volume

16.86mL

Finial Volume

18.45mL

Figure 2: From Part 2

Mass of the Empty 50-mL Flask

37.393g

Weight of Flask Filled with 50-mL of Water

87.096g

Weight Closest to 2.92g NaCl That Was Obtained

2.9412g

Mass of Filled Flask With the 1:1 Solution

89.1207

Mass of Filled Flask With the 1:2 Solution

88.2571

Mass of Filled Flask With the 1:10 Solution

87.4366

Sample Calculations:

Part 1:

Volume of the Metal

Volume Metal= Volume final- Volume Initial

Volume final=18.45mL, Volume Initial=16.85mL

1.60mL= 18.45mL-16.85mL

Volume of Metal=1.60mL

Density of Metal

Density of Metal= Mass of Metal ÷ Volume of Metal

Mass of Metal = 13.22g Volume of Metal = 1.60mL

8.26g/mL = 13.22g ÷ 1.60mL

Density of Metal=8.26g/mL

Part 2:

Mass of Distilled Water

Mass of Water = Mass Filled – Mass Empty

Mass Filled= 87.0966g Mass Empty= 37.393g

49.704g=87.0966g- 37.393g

Mass of Distilled Water=49.704g

Density of Water

Density of Water= Mass of Water ÷ Volume of Water

Mass of Water= 49.7036g Volume of Water= 50mL

.99g/mL= 49.7036g ÷ 50mL

Density of Water=.99g/mL

Amount of NaCl for Stock Solution

Molarity (M) = moles solute ÷ Liters of Solution

Molarity= 10 M, moles of solute= x, Liters of Solution= 0.0500 x=(0.0500moles NaCl)(58.44g NaCl/moles NaCl)

x=2.92g NaCl

Actual Concentration Made

Weighed NaCl= 2.9412g

(2.9412g NaCl)(1mol NaCl/58.44g NaCl)=.503mol

Molarity= x÷ 0.0500L

x=.503mol

1.006mol/L=.503mol÷ 0.0500L

Molarity= 1.006 mol/L

Mass of Stock Solution

Mass Solution= Mass filled2- Mass empty2

Mass filled 2=89.1207g, Mass empty 2=37.393g

51.728g=89.1207g- 37.393g

Mass Solution=51.728g

Density of Stock Solution

Density of Stock= Mass of Stock ÷ Volume of Stock

Mass Stock= 51.7277g, Volume of Stock= 50mL

1.0g/mL=51.7277g÷50mL

Density of Stock Solution= 1.0g/mL

Calculation to find Volume of Stock Solution needed for the 1:2 Ratio Solution (M1)(V1)=(M2)(V2)

M1=1.006mol/L, V1=x, M2=.1006mol/L, V2=50mL

(1.006mol/L)(V1)=(.1006mol/L)(50mL)

V1=25mL

Volume needed=25mL

Mass of the 1:2 Solution

Mass of the Solution=Mass filled3- Mass empty

Mass filled3= 88.2571g, Mass empty= 37.393g

50.864g=88.2571g-37.393g

Mass of 1:2 Solution=...

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