Essay On Density Determination Lab

The Congress authorized the amount of copper in a penny after 1982 to be 2.5% by mass. The mean value found from this lab was 3.018%. There were no discernable variations based off of the penny’s apperance or mint date. The value reached from this lab is significantly different from the authorized copper content.

because each of the objects displaced the water by 1 mL, their mass over that mL is their density.

10. The accepted value for the density of aluminum is 2.699 g/cm3. Using this density and the masses of your two samples of aluminum foil, calculate the volume of aluminum in each sample: the regular vs. the heavy duty. (Note: You will have to use a bit of algebra and the formula D = m/v for this calculation!)  You must show all your work. (15 pts)

Purpose: To become familiar with the International System of Units and common laboratory equipment and techniques. To learn how to determine volume, mass, length, and temperature of a wide variety of items. To learn how to calculate density and concentration of dilutions.

G. You are given a small piece of gold colored material and want to determine if it is actually gold. Using the Archimedes’ Principle you find that the volume is 0.40 cm3 and the mass is 6.0 g. What conclusions can you reach from your simple density analysis?

10. As described in problem 7, a procedure was developed to determine the percent zinc in post 1982 pennies. In that procedure 50 ml of an HCl was used to react (dissolve) all of the zinc in the penny. To ensure complete reaction, the solution contains twice as many moles of HCl that is actually needed. To determine the percent zinc in the penny, the excess (unreacted) HCl was titrated with NaOH. Determine the concentration of NaOH needed if you want to use approximately 25 mL of NaOH to titrate the excess HCl.

This experiment was performed to observe differences in density based on the chemical makeup of an object. Pennies minted before 1982, pennies minted after 1982, and an unknown metal sample was tested to see if there were any differences in their densities. Ten pennies from each category and the metal sample were weighed using a scale to find mass and the displacement method was used to find their volumes. The masses and volumes were then used to calculate the densities of the pennies (D=m/v). The density of the pre-1982 pennies were 8.6 g/mL while the post-1982 pennies were 6.9 g/mL. The metal sample’s density was 1.7 g/mL. Following the experiment we were given the real densities of each item to calculate the percent error with the formula

Weight 30 dry pre-82 pennies which get 89.77g, using 30ml initial volume measuring the volume of 30 pennies, record the data 10.0ml. Using equation Density= Mass/Volume, get the density of the pre-82 pennies is 8.98g/ml. Then calculate the error%=0.10%, and the deviation%=1.29%.

CHM130 Lab 6 Exploring Density Name A. Data Tables Place your completed Data Tables here Part IIIa (3 points) Volume of water in graduated cylinder (mL)10 mlMass of rubber stopper (g)11.15Volume of water and rubber stopper (mL)16.5 Part IIIb (6 points) Volume of water in graduated cylinder (mL)20Mass of iron nail (g)3.66Volume of water and iron nail (mL)20.5 Part IV (20 points) Type of Aluminum FoilMass (g)Length (cm)Width (cm)Volume (cm3)Thickness (cm)Regular.63g15 cm 10.02 cm.21 cm3.0014 cm Heavy Duty.97g15 cm10.01 cm .36 cm3.0024 cm B. Follow Up Questions Show all work for questions involving calculations. Part I Use the concepts/vocabulary of density to explain why the liquids formed layers in Part I of the procedure. (8 pts)

10. As described in problem 7, a procedure was developed to determine the percent zinc in post 1982 pennies. In that procedure 50 ml of an HCl was used to react (dissolve) all of the zinc in the penny. To ensure complete reaction, the solution contains twice as many moles of HCl that is actually needed. To determine the percent zinc in the penny, the excess (unreacted) HCl was titrated with NaOH. Determine the concentration of NaOH needed if you want to use approximately 25 mL of NaOH to titrate the excess HCl.

volume of 15.3 cm3. Were the coins gold (d = 19.3 g/cm3) or just yellow brass (d = 8.47 g/cm3)?

In Measuring and Understanding Density, several experiments were performed to find density of regularly shaped objects, irregularly shaped objects, liquids and gasses. An additional experiment was done to find the specific gravity of a sampling of liquids. The purpose of the experiment was to provide a better understanding of density and to be able to extrapolate unknowns based upon these calculations. The experiments yielded data in keeping with Kinetic-molecular theory in regards to the density of water versus its temperature. Key measurements and formulae were also used to determine densities of metal and plastic objects as well as irregularly shaped rocks. It is possible to find the density of an object (be it liquid, gas or

D. A sample of gold (Au) has a mass of 26.15 g. Given that the theoretical density is 19.30 g/mL,

Seven various household objects were chosen to measure using a digital gram scale. Each object’s mass was estimated by lab students and recorded in data table 4. A quarter, ball point pen, rubber bulb, large paper clip, green crayon, house key and a copper penny masses were estimated and recorded in data table 4. Each object was placed on the scale individually and its actual measurement was recorded in data table 4. As we started estimating the household objects we were often not correct in our estimations. As we measured more and more objects, we got better in our estimations by comparing objects with known masses and comparing them with the unknown

The purpose of this lab was for the student to get involved with his or hers new lab kit as well as being able to know, identify and use each other tools provided in the kit. Another key learning aspect of this lab is to teach the student how to measure properly the many units in the SI system. I will be using laboratory dilutions, measurements, and weights to then calculate using algebraic formula.