Density

Experiment 03 – Density

CHM 1045L – Fall 2020 – PBSC

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Pre-lab Setup

Type out the chemicals used in this experiment, their hazards if applicable, and any other safety concerns associated with this experiment.

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Type the procedure for this experiment in your own words. Feel free to use a bullet list (avoid huge paragraphs).

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Pre-lab Questions

1. Describe what is meant by “taring.”

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2. Consider: When we make the density plots, should the y-intercept be set to y = 0? Why or why not? Briefly explain your answer.

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3. A metal lump has a mass of 25.111 g. When it is placed in a graduated cylinder containing 15.0 mL of water, the water level rises to 37.6 mL. Calculate the density of this metal to the correct number of significant figures. Include units and show all work at the bottom of the worksheet to receive full credit.

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Calculations/Work

1. Add a picture of your work for pre-lab question #3 below.

Data

Table 1. Determining the Densities. Fill out the following table with your collected data. Your table should have 4-6 data entries for each solution – you do not have to have all cells filled if you did not make all 6 measurements. Be sure to record your measurements with the appropriate number of significant figures.

Graduated Cylinder Used:

☐ 10 mL ☐ 25 mL

Solution Type:

☐ Sugar ☐ Salt

Percent Soln.

Volume (mL)

Mass Cyl. (g)

Mass Soln. + Cyl. (g)

Mass Soln. (g)

0 %

10 %

20 %

30 %

40%

Table 2. Density Results. Fill out the following table with your collected data.

Percent Soln.

Equation of Best-Fit Line

Density (slope), (g/mL)

R2 value

0%

10%

20%

30%

40%

Post-lab Questions

1. The density of pure water at 4.0 °C is 1.000 g/mL. Answer the following questions using your 0% solution data.

a. How close was your calculated density to this value? Speculate about why your density may not match this value (be specific).

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b. Would using different volumes of water have an impact on your accuracy? Briefly explain why or why not, being sure to use specific vocabulary (review the lab manual).

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1. A sugary fruit drink has a sugar concentration of 30% w/w. If a student specifically wants 750. mL of the drink, how many grams should you weigh out on the scale? Assume the drink has the same density properties as you 30% w/w solution (even if you did saltwater). In words, briefly explain how you determined your answer.

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Calculations/Work

1. Add a close-up focused image of one of your graduated cylinder volume readings. Be sure the graduated cylinder is level and that the photo is taken at the level of the solution surface. Under the photo, include your reading of the volume (including uncertainty and units).

2. Add screenshots of your Excel graph. Make sure the graph is correctly formatted and labeled with which solution is which.