Density Lab Report

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Saint Joseph's University *

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120

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Chemistry

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Jan 9, 2024

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Determination of Density Lab 11 th September 2023 Results Table 1 . Data for determination of the density of water. Temperature of the water = 22 o C Trial Mass of flask empty (g) Mass of flask full (g) Mass of water (g) Initial volume (mL) Final volume (mL) Volume of water (mL) Density (g/mL) 1 48.6447 g 78.3417 g 29.6967 g 0.00 mL 30.0 mL 30.0 mL 0.98989 g/mL 2 48.6924 g 78.5527 g 29.8603 g 0.00 mL 30.0 mL 30.0 mL 0.99534 g/mL 3 48.6101 g 78.4841 g 29.8740 g 0.00 mL 30.0 mL 30.0 mL 0.99580 g/mL Average density of water = 0.99368 g/mL Precision = 5.9476 ppt %Error = 0.41291% Table 2. Data for determination of the density of an unknown liquid. Temperature of the unknown = 23 o C. Trial Mass flask empty (g) Mass flask full (g) Mass of unknown (g) Initial volume (mL) Final volume (mL) Volume of unknown (mL) Density (g/mL) 1 48.6298 g 73.1011 g 24.4713 g 0.00 mL 30.0 mL 30.0 mL 0.81571 g/mL 2 48.7805 g 73.1114 g 24.3309 g 0.00 mL 30.0 mL 30.0 mL 0.81103 g/mL 3 48.5257 g 72.7266 g 24.2009 g 0.00 mL 30.0 mL 30.0 mL 0.80670 g/mL 4 47.5417 g 71.5814 g 24.0397 g 0.00 mL 30.0 mL 30.0 mL 0.80132 g/mL Average density of Unknown = 0. 80869 g/mL Precision = 17.794 ppt Name of Unknown – 1 propanol Unknown code – A %Error = 18.933 %

`Calculations The first calculation that needed to be done was to find the mass of just the water. That was done by subtracting the mass of the flask with water from the mass of the empty flask. In trial 1 the mass of the water was 29.6967 g. In trial 2, the mass was to be found at 29.8603 g; for trial 3, the mass of water was 29.8740 g. After that, the volume of the water needed to be found which was 30.0 mL for all three trails. With both the mass of water and volume of water calculated, the density can be found. Density is volume divided by mass. In trial 1 the density was 0.98989 g/mall. This was calculated by dividing the 30.0 mL of water by 29.6967 g of water. Trail 2 the density was 0.99534 and trail 3 the density was 0.99580. Since all three densities have been calculated, the average density of water can be found. This is by adding all three densities together and dividing it by 3. The average was 0.99368 g/mL. For Table 2 of the unknown liquid, the same calculations were used to find the density of the unknown which came out to be 0.79711 g/mL. To calculate the precision in parts per thousand the lowest value gets subtracted by the highest value and then the average gets divided by that number. Finally, it gets multiplied by 1000. For Table 1, the lowest value was 0.98989 and the highest value was 0.99580. When those were subtracted the number came out to be 0.00591. The average density of water which was found earlier gets divided by this new number and came out to be 0.0059476. This then gets multiplied by 1000 and the ppt came out to be 5.9476 ppt. These same calculations are done for Table 2 and the precision for the unknown liquid was 17.794 ppt. The percent error for Table 1 was to be found at 0.41291%. This was done by subtracting the accepted value from the observed value. The accepted value for the density of water at 22 o C is 0.99780. 0.99780 was subtracted by the observed value which was 0.99368 and came out to be 0.00412. This gets

divided by the accepted value again and then multiplied by 100. The same process was done for Table 2 for the unknown liquid. The percent error came out to be 18.933% Conclusions The unknown liquid in the lab's density was calculated to be 0. 80869 g/mL. This matches the density of the unknown substance in the table value of the unknown substances. The unknown liquid in our lab is 1-propanol. This was done by matching the average density that was found and matching it with the densities in the table. This lab went smoothly especially for Table 1 as the source of error was only 0.41291%. On the other hand, though for Table 2, the percent error was 18.933% and the precision by PPT was 17.794. These numbers are kind of high. A source of error that happened was that the buret and flask were not rinsed several times with a small portion of the unknown before measuring. We just rinsed it with water and started from there so there might have been water residue left over which messed with the weight of the liquid and messed with the overall density. The temperature of any liquid affects its density majorly. If the temperature of a liquid is very cold or even frozen the density of it will be higher if the liquid is warmer or hot. For example, ice which is frozen water floats because its density is very high.

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