Experiment - Density as a Property of Matter

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Apr 3, 2024

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Name _Teawna Stetson_________________________ Date _03/18/2024__________ Experiment Density as a Property of Matter Supplies Needed: Provided by the Kit: Set of Four Stoppers Rod Set 1 Rod Set 2 Graduated Cylinder Caliper Unknown Aqueous Solution Scale that measures in grams to 2 decimal places You need to provide: Metric ruler Part I. Density as an Intensive Property By definition, an intensive property of some type of matter is independent of the size of the sample. Therefore, if you measure the mass and volume of several samples of the same type of matter, the density should remain a constant value. In Part I, you will test that hypothesis. 1. A set of four stoppers of different size but made of the same type of matter are provided. Take a digital picture of your stoppers and include with your report. 2. Determine the mass of each item separately and record the mass on the data table below. 3. Determine the volume of each item separately using the volume by displacement method where you first measure the volume of water in a graduated cylinder. Then carefully slide the stopper into the cylinder to avoid splashing and record the volume of the water + stopper. To get the volume of the stopper, subtract the volume of the water in the graduated cylinder (your first measurement) from the volume of the water + stopper. The stopper must be completely submerged for this to work. If you don’t have enough water to submerge it completely, start over with more water. Take appropriate picture(s) showing how you measured the volume of one of the stoppers and include the picture(s) with your report. 4. Record the data and final volume on the data table below. 5. Calculate the density of each item using the measured mass and volume values and record the experimental density on the table below. Show your calculations in the space within the table. 6. Determine the average density of the four objects and the standard deviation. Show your calculations. 1

Name _Teawna Stetson_________________________ Date _03/18/2024__________ Item 1 Item 2 Item 3 Item 4 Mass 8.27g 7.35g 5.87g 4.00g Volume Water ___54.0mL________ Water + stopper__61.0mL____ __ Stopper = _7.0mL_______ Water ___54.0mL________ Water + stopper__60.0mL____ __ Stopper = _6.0mL_______ Water ___54.0mL________ Water + stopper__58.5mL____ __ Stopper = _4.5mL_______ Water ___54.0mL________ Water + stopper__57.0mL____ __ Stopper = _3.0mL_______ Density calculatio n 8.27g/7mL 7.35g/6mL 5.87g/4.5mL 4.00g/3mL density 1.18g/mL 1.23g/mL 1.30g/mL 1.33g/mL Calculate the average density, showing your calculations. [add your experimental values and then divide the sum by the number of factors added]. Calculate the standard deviation: standard deviation ≈ range √ N = highest value − lowest value √ N Average density ± S.D. = __1.26g____________________ ± ___0.08g_______________ Questions: 1. Compare the experimental density value for your four items. How do they relate to each other? The density does go down as the stoppers get smaller but there is not a huge difference. 2. Explain how the results of Part I relates to the definition of an intensive property – validate or disprove that density is an intensive property? I think this proves that no matter the number of other parts of the sample, the density of the object stays the same or mostly the same. 3. Describe what errors might occur that would lead to different density values within your four samples? There could be errors for water drops already in the cylinder that may add to the amount of water. 2

Name _Teawna Stetson_________________________ Date _03/18/2024__________ Part II. Combining mass and volume measurements – Density determinations. Two sets of cylinders will be provided. Make sure you have the correct items before beginning this exercise. Take a digital picture of each set of rods with the set labeled. Include the picture with your report. Examine each set closely. What do you observe about each set? Set 1 All the rods are different colors and sizes. Set 2 all the rods are the same sizes but different colors and weigh different sizes. Determine the density of each rod In each case, you will need to describe the rod in order to correlate its identity to its density. 1. Determine the mass of each rod in both sets by direct measurement on a balance. Record the mass values on the data table below. 2. Using an appropriately sized graduated cylinder, determine the volume of each rod by displacement . Remember to carefully place the rod in the cylinder containing the water to avoid breakage. Record your measurements and the volume values on the data table below. Take a digital picture of the rod in the cylinder and include with your report. 3. Calculate the density of each rod from your measurements and record the densities on the data table below. Show your calculations in the space provided. SET 1: Rod 1 Rod 2 Rod 3 Rod 4 Mass 15.01g 14.73g 15.04g 15.05g Volume Vol water _54.0mL__ Vol water + rod _67.0mL__ Vol rod _ 13.0mL Vol water _54.0mL__ Vol water + rod _68.0 mL __ Vol rod _14.0mL Vol water _54.0mL __ Vol water + rod _55.2 mL __ Vol rod _1.2mL Vol water __54.0mL _ Vol water + rod _60.0 mL __ Vol rod _6.0mL Density calculatio n 15.01g/13.0mL 14.73g/14.0mL 15.04g/1.2mL 15.05g/6.0mL density 1.155g/mL 1.052g/mL 12.53g/mL 2.508g/mL SET 2: Rod 1 Rod 2 Rod 3 Rod 4 Mass 53.80g 50.00g 57.14g 17.72g Volume Vol water _54.0mL Vol water + rod __60.0 mL ______ Vol rod _6.0mL_____ Vol water _54.0mL Vol water + rod __60.0 mL ______ Vol rod __6.0mL ____ Vol water _54.0mL Vol water + rod __60.0 mL ______ Vol rod __6.0mL ____ Vol water _54.0mL Vol water + rod __60.0 mL ______ Vol rod __6.0mL ____ Density calculatio n 53.80g/6.0mL 50.00g/6.0mL 57.14g/6.0mL 17.72g/6.0mL density 8.967g/mL 8.333G/mL 9.523g/mL 2.953g/mL Questions: 3

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Name _Teawna Stetson_________________________ Date _03/18/2024__________ 1. Describe the similarities among the rods of set 1. Describe the differences among the rods of set 1. Similarities: The mass of the rods are very similar considering they have different sizes. Differences: The rods have different sizes, colors, and masses. 2. Describe the similarities among the rods of set 2. Describe the differences among the rods of set 2. Similarities: All the rods have the same size. Differences: All the rods have different colors and masses. 3. What conclusion(s), if any, can you draw when considering the appearance of a rod and the density of the rod? The more solid color, the heavier it is. Even if they are the same size, the masses could be different. Part III. Density as a means of identifying a sample of matter. A. Density of a stopper 1. Choose one of the regularly shaped stoppers from the set provided. Before making any measurements, describe the appearance of the stopper in the space provided. Take a picture of your stopper and include it in your report. 2. Calculate the volume using volume by displacement as described in Part I. 3. Using a balance, determine the mass of the stopper. Record the mass in the data section below. 4. Using these experimental values for the mass and the volume calculate the density of the block and record the density in the data section below. 5. Compare your experimental values with the reference values listed on Blackboard and determine the identity of your sample. Record your findings in the data section below. 6. Using the formula provided in the Introduction, determine the % difference (% error) between your experimental value and the reference value provided. Describe the appearance of your stopper: Second largest stopper ________________________________________ In recording the following measurements, make sure that you use the correct number of significant digits and units for each measurement. 1. Volume of water ___54.0mL__________ 2. Volume of water + stopper___60.0mL_____________________ 3. Volume of stopper_____6.0mL___________ 4. Mass of stopper ___7.35g____________ 5. Density of stopper ___1.23g/mL_________ 6. Identity of your stopper from the list: ___#2__________ 4

Name _Teawna Stetson_________________________ Date _03/18/2024__________ 7. Reference value for the density from the file labeled CRC information. __0.95g/cm 3 _______________________ 8. % difference (% error) from reference value: __________ Calculations: Calculate the density of your stopper: Calculate the % difference between your experimental value and the given theoretical value: % difference = | theoretical value − experimental value | theoretical value X 100% = _______% B. Determination of the density of a cylindrical metal rod using two different methods to measure volume. 1. Volume of the metal rod by displacement a. Choose one of the metal rods from the set provided and describe its appearance in the data section below. Take a picture of the rod and its set number and include with your report. b. Determine the mass of a metal rod to the nearest 0.01 g and record the mass on both line 1 and line 6 in the data section below. c. Determine the volume of the metal rod by the displacement method. 1) Fill a 25 mL graduated cylinder with 10-15 mL or water. Record the volume of the water to the nearest 0.01 mL in the data section below. 2) DO NOT DROP THE METAL ROD INTO THE GRADUATED CYLINDER!!! Hold the graduated cylinder at an approximately 45° angle and slide the metal rod into the cylinder. The water must completely cover the metal rod. 3) Measure and record the volume of the water plus the metal rod in the cylinder to the nearest 0.01 mL in the data section below. 4) Calculate the volume of the metal rod by subtracting the initial volume of water [line 2 ] from the total volume of the water plus the metal rod [line 3 ] and record on line 4 in the data section below. 5) Calculate the density of the metal rod using the pre-determined mass [line 1 ] and volume [line 4 ] and record the density on line 5 in the data section below using the correct number of significant figures. 2. Determine the volume of the metal rod using the mathematical formula. a. Using a caliper , measure the diameter of the metal rod and record the value on line 7 in the data section below. If you haven’t used a caliper before, read the directions located in the file called Using a Caliper. Take a picture of caliper measuring the diameter of the road and include it in your report. b. Determine the radius by dividing the diameter by 2 and record the radius on line 8 . Measure the height (or length) of the metal rod and record on line 9 in the data section below. c. Using the following formula for the volume of a cylinder, calculate the volume and record the value on line 10 in the data section below. V =  r 2 h Calculation of the volume of the metal rod: 5

Name _Teawna Stetson_________________________ Date _03/18/2024__________ d. Calculate the density of the metal rod using the predetermined mass [line 6 ] and the calculated volume [line 10 ] and record the density on line 11 in the data section below. Calculation of the density of the metal rod: Describe the appearance of your metal rod: Bronze__________________________ Displacement Method 1. Mass of metal rod ___7.35g________________________________ 2. Volume of water ___54mL________________________________ 3. Volume of water + rod ___60.0mL ______________________________ 4. Volume of metal rod ___6.0mL_______________________________ 5. Density of metal rod __1.23g/mL______________________________ Mathematical Method 6. Mass of metal rod __7.35g________________________________ 7. Diameter of metal rod __1.40cm_______________________________ 8. Radius of the metal rod __0.7__________________________________ 9. Height of metal rod __5.12cm_______________________________ 10. Volume of metal rod _7.88cm 3 ______________________________________ 11. Density of metal rod __0.93g/cm______________________________________ Questions: 1. Compare the density determinations from line 5 and line 11 . How do the values for the density of the metal rod compare using the two methods? List and explain at least three factors that might contribute to any differences between the two volume measurements.  The volume is eye-leveled, and the water level may have not been exact.  Human error of reading data.  The cylinder used did not break down the water into 100ths like the volume in mathematical method did. 2. The level of precision in the manufacture of these metal rods is greater than that of the cubes. To determine the identity of the metals in the rods, we use a more accurate set of reference values. Therefore, to determine the identity of your metal rod, compare your experimental value with the reference values listed on Blackboard. Based on these reference values, you predict that the identity of your metal rod is aluminum ___ 3. Compare the two experimental values you determined with the reference value. How do these two values compare? What might account for any differences between the values you determined in the laboratory and those provided in the reference handbook? _ Aluminum density maybe a little different based of the human error component and we don’t know if its pure aluminum or not, this may alter the density of it. 6

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Name _Teawna Stetson_________________________ Date _03/18/2024__________ Part IV. Determining the concentration of an aqueous solution using the density. You will be using an aqueous solution of sodium chloride. Three aqueous solutions of different concentration of sodium chloride have been prepared but the labels became detached. The only way to determine the identity of the solutions was to determine the density of each solution and then compare that experimental value with the actual density of each of the salt concentrations. You know that the reference values for the density of several concentrations of sodium chloride are known. A standard curve can be prepared by plotting a graph of the relationship between density and concentration which is a linear relationship. The density of the solution with an unknown concentration can then be determined from the graph. The reference values for the solutions are: Sodium Chloride Solutions Concentration Density, g/mL 5% 1.036 10% 1.073 15% 1.111 20% 1.150 25% 1.191 Prepare a standard curve for the relationship between the concentration (x-axis) and density (y-axis) values provided in the table above for your solution (either aqueous sodium chloride or aqueous alcohol). Information on how to draw the standard curve are provide on the following page. 7

Name _Teawna Stetson_________________________ Date _03/18/2024__________ Preparing a graphs A line graph can be used to show the relationships between two or more factors, in this case, concentration and density. For a line graph, the factors are usually defined either in numeric terms or by some measurable term. These factors are represented on the two axes of your graph. The horizontal scale is sometimes called the horizontal axis or the x-axis and the vertical scale is sometimes called the vertical axis or the y-axis . Each axis on the graph must be labeled for identification. To do this, define the scale by indicating the quantity to be represented on that axis. In deciding which quantity to place on which scale, the independent variable, or the variable that you manipulate, is usually placed on the x-axis . The dependent variable, or the variable that responds, is usually placed on the y-axis . How to Construct a Line Graph on Paper Step What to Do How to Do It 1 Identify the variables a. Independent variable, in this case the concentration, should be placed on the X- axis b. Dependent variable, in this case density, should be placed on the Y-axis 2 Determin e the variable range For each variable, subtract the lowest data value from the highest data value a. For the x -axis, the concentration ranges from 0  100 % b. For the y -axis,  If you are using the aqueous salt solution, the density range provided in the table is 1.00 g/mL (the density of water) to 1.191 g/mL (the density of a 25% m/m solution of salt in water) so the scale on the y -axis should be slightly greater than that range. Therefore, the lowest density value should be 0.90 g/mL and the highest density should be 1.25 g/mL.  If you are using the aqueous alcohol solution, the density range provided in the table is 0.79 g/mL (the density of 100% alcohol) to 1.00 g/mL (the density of pure water). Therefore, the lowest density value on your graph should be 0.75 g/mL and the highest density should be at 1.05 g/mL. 3 Determin e the scale of the graph Use the largest scale possible such that the graph fills a least 2/3 of the paper. a. You can draw the graph with the paper upright (portrait) or sideways (landscape), whichever is most appropriate for the particular graph. b. Use an appropriate scale, one that is not difficult to plot. For example, if the x -axis has a range from 0% to 100%, an appropriate range might be 5 or 10 % per major division. Since the y -axis represents much smaller numbers, an appropriate range might be 0.05 or 0.10 g/mL per major division. c. You can determine an appropriate scale by counting the number of lines on the y -axis and dividing this by the range of your densities. For example, if your range is 1.10 g/mL  0.75 g/mL and you have 7 major divisions on your y -axis, then ( 1.10 − 0.75 g/mL 7 lines = 0.05 g/mL line . d. Start by marking your lowest point on the y -axis is at 0.75 and add 0.050 for each major line above that. 4 Label each axis Since the label tells what data the lines on your graph represent, be sure to include both the numbers for your scale and the units being represented. 5 Plot the data points When plotting the data points on the graph use a dot or small X but make sure they can be easily seen. 6 Draw the graph a. For this type of data set, the graph should be a best fit line. In this type of line, you do not connect the dots. b. To draw a best-fit line, it is easiest if you use a clear plastic ruler. Place the 8

Name _Teawna Stetson_________________________ Date _03/18/2024__________ ruler so that you can draw a line so that it gets as close as possible to all of the dots with half the dots on one side of the line and the remaining half on the other side of the line. On the sheet of graph paper provided (not generated on a computer program), prepare a standard curve for the relationship between the concentration (x-axis) and density (y-axis) values provided in the table above for your solution (either aqueous sodium chloride or aqueous alcohol). This standard curve should show the linear relationship between the percent concentration and the density of a given aqueous solution. If the points are not perfectly linear, draw a best-fit line , not a connect-the-dots line. The graph that you prepare from the above reference values will be used to determine the concentration of your test solution.  Place the concentration on the x -axis and the density on the y -axis similar to the graph below.  If using an aqueous salt solution, the lowest density is 1.00 g/mL and the highest value is 1.191 g/mL, so make the scale on the y-axis begin at 0.95 and go to 1.25 g/mL.  To determine how to space the increments on your y-axis, see the information on the previous page.  Your graph should look similar to the one shown to the right which is just an EXAMPLE of how to prepare a graph. 0 5 10 15 20 25 30 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 concentration (%)  Once you have completed the determination of the density of your test solution you can determine the concentration of your test solution: o locate the density value on the y -coordinate o draw a line from the y -axis to the standard curve o draw a line from your standard curve to the x -axis. o The point where your line crosses the x -axis is the percent concentration of your test solution To determine the concentration of one of the solutions provided. 1. Each test solution of unknown concentration is labeled with a letter. Place that letter on the line provided in the data section below so that you can check your results. 2. Determine the mass of a clean, dry 10 mL graduated cylinder and record the mass on the line provided in the data section below to the level of accuracy of the balance you are using. 3. R emove the cylinder from the balance and fill the cylinder with your solution to a level between 6 and 10 mL. It is best if the volume selected is on a graduation mark on the cylinder. 4. Record that volume to the correct level of precision based on your graduated cylinder on the line provided in the data section below. 5. Determine the mass of the cylinder plus the solution and record the mass on the line provided in the data section below. Take a picture of your cylinder on your balance clearly showing both its mass and volume. Include the picture in your report. 6. Calculate the mass of the solution by subtracting the mass of the empty cylinder [line 1 ] from the mass of the filled cylinder [line 2 ] and record the mass of the solution on the line provided in the data section below. 7. Using these values, calculate the density of the solution by dividing the mass of the solution [line 3 ] by the volume of the solution [line 4 ] . Record the density on the line provided in the data section below. 9 Density (g/mL)

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Name _Teawna Stetson_________________________ Date _03/18/2024__________ 8. From the graph you prepare from the reference values in the above tables, determine the concentration of your solution and record that concentration on the line provided in the data section below. The experimental value for density becomes the y -coordinate in the determination of the concentration and the x -coordinate at that point is the concentration. Data Collection: Identify your sample: ___A_______ Analysis of your test solution 1. Mass of the graduated cylinder __2.44g______________________________________ 2. Mass of the cylinder + solution_10.40g_______________________________________ 3. Mass of the solution _7.96g_______________________________________ 4. Volume of the solution __8mL______________________________________ 5. Density of the solution _1.0_______________________________________ 6. Concentration of the solution as read from your prepared graph ____5%_______________ 7. Take a picture of your graph or scan it into a jpg format and include it with your report. 10

Name _Teawna Stetson_________________________ Date _03/18/2024__________ 11

Name _Teawna Stetson_________________________ Date _03/18/2024__________ 12

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Name _Teawna Stetson_________________________ Date _03/18/2024__________ 13

Experiment - Density as a Property of Matter

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