Graphical Method for Calculating Density
To graphically determine the density of two different substances. Class data will be used so as to include multiple trials.
Proper safety precautions for this lab is to wear goggles, keep substance a safe distance from mouth and nose.
1. Calculate the slope of the line in the graph above. Use the rise over run method. If you don’t know how, ask a friend or look it up. Clearly show your work for the calculation and include units in your answer. – Equation for rise over run for line in graph I used… 2.75/6= .46
2. The slope of this line represents the DENSITY of the substance.
1. Obtain samples of lead and brass. The samples must be clean and dry (think about why.) 2. Obtain the mass of an empty beaker, and then carefully add your lead to the beaker. Record the new mass of beaker + metal.
3. Use the water displacement method to find the volume of the lead. Fill a graduated cylinder about half-full with tap water. Record the initial volume. Very carefully add your metal sample to the graduated cylinder. If this happens, you need to start over at step 2 with a fresh dry sample. If water does not cover the metal at this point, you need to start over with a fresh dry sample. Record the final volume. 4. Repeat steps 2 and 3 for the other metal.
5. Dry both samples by bringing them to the front and placing them in their respective strainers.
Data and Observations
1. “What does this experiment demonstrate about the density of a substance”- It shows the density of a substance determining the amount can very when it comes to results.
2. “Do you think density could help identify an unknown substance? Why?”- Yes, because once you find the density you can then find substances with that density and the substance with the same density will be your unknown substance.
3. “Look up the accepted values for the density of aluminum and iron. Calculate the percent error by comparing your densities (question 1) to the accepted values.
Show all work”- Accepted values for iron are 78g and my amount was 67.03g so we got a percentage error of 8%, (-88.53x100=8.8% error) Accepted values for aluminum are 27g and I got 17.03g for my amount so I got a percentage error of