Portfolio Assignment #2:
Making Sense of Density I. Purpose: To use density to identify eight unknown substances II. Materials: 1.) triple-beam balance; 2.) ruler; 3.) beaker with water; 4.) calculator; 5.) eight density blocks III. Procedure: 1) 2) 3) 4) 5)
Select each block and determine the mass in grams Figure out the volume of each (15.625) Based upon the mass and volume, determine the density of each block (mass/volume) Place each block in the beaker with water and observe if the block floats or sinks Determine the substance of the blocks by looking up the densities of pure substances
IV. Data: Block # 1 2
Mass
Volume
Density
(g)
(cm3)
(g/cm3)
Sink/Float Substance
15.5 g 7.1 g
15.625 15.625
.992 .4544
Floats Floats
Polyprolene Pine
3
127.6 g
15.625
8.1664
Sinks
Steel
4
20 g
15.625
1.28
Sinks
Acrylic
5
44.4 g
15.625
2.8416
Sinks
Aluminum
6
144.2 g
15.625
9.2288
Sinks
Copper
7
13 g
15.625
.832
Floats
PUC
8
138.4 g
15.625
8.8576
Sinks
Brass
V. Conclusion 1. Convert each density measurement to kg/m3. g/cm3
Block # 1 2 3 4 5 6 7 8
Kg/m3 .992 .4544 8.1664 1.28 2.8416 9.2288 .832 8.8576
992 454 8166 1280 2842 9229 832 8858
2. Every pure substance has a specific density. You can use density to identify what a substance is by comparing the density you calculated to the known density of certain pure substances. The data above shows that we calculated the densities of blocks with unknown substances and then compared them to known densities we looked up. 3. If you were to examine a smaller piece of the same blocks, the density would not be different. There is a specific density for every pure substance. 4. It's important to dry off the blocks after dipping them in the water, because the water may soak into the block, therefore endangering the validity of the outcomes when you try to weigh the substance. 5. To find the density of olive oil, one would put the oil into a small container, weigh it, subtract the weight of the container, and then divide it by the volume of the oil. The correct density of olive oil is 800-920 kg/m3.
Portfolio Assignment
Constructing a Model I. Purpose: To understand how scientists make inferences about atoms II. Materials: 1.) Closed container; 2.) various objects; 3.) balance III. Procedure: 1) Pick another student’s closed container and observe it (e.g. try to guess how many objects are inside and what kind) 2) Weigh the box on the balance to determine the weight altogether 3) Now open the container and feel inside to produce a better guess at what is inside. 4) Then look inside to see if your guessed were correct about the contents 5) Weigh each object in grams IV. Data: Part A: Closed Container Container # of Objects Mass of Objects (w/ box) Kind of Objects Block, small sphere, dice 1: Tommy 3 364 g Paper clips 2: Claire 3-5 90 g A figure, game piece 3: Philip 2 99 g
Part B: Open container without looking Container # of Objects Mass of Objects (w/ box) Kind of Objects Shark figure, bone, dice 1: Tommy 3 364 g Bracelet, bow, charm 2: Claire 3 90 g Rubber duck, spoon 3: Philip 2 99 g
Part C: Open container with looking Container 1: Tommy 2: Claire 3: Philip
# of Objects 3 6
Mass of Objects 50 g 8.25 g
2
93 g
Kind of Objects Shark figure, bone, dice Flower charm, pin, 2 plastic gems, bracelet, bow Rubber duck, spoon
V. Analyze and Conclude: 1.) Scientists often use more than one method to gather data. This was illustrated in this experiment by first trying to figure out the information of the objects without opening the container, then opening it, then looking at the objects inside. Three different tables of data were used in this experiment. 2.) Out of the observations that were made, the number of objects and the mass of the objects were quantitative and the kind of objects were qualitative.
3.)
Tommy used a packing box as his container and placed a shark figure, a bone, and a dice. By shaking the box, I was able to presume that there were three objects and that it weighed 364 g all together. By reaching inside in the next method, I was able to confirm that there were three objects inside the box and ended up guessing what the objects were inside. The last method revealed that I was correct in my assumptions about the objects inside, which all weighed out to be 50 g.
Lab #3
The Mole Concept I. Purpose: To identify each sample based on the observation and numerical data; II. Materials: 1) mole sample set; 2) balance III. Procedure: 1) Observe each sample by its qualitative properties (i.e. silver, metallic‌) 2) Weigh each sample on the balance and record the masses 3) Find out how many moles are in each sample 4) Record the number of atoms in each mole (Avogadro’s #) 5) Identify each sample by comparing your masses to the molar masses for each element on the Periodic Table IV.
Data: A. Observations
Sample A B C D
Observations Silver, metallic, heavy Light silver, metallic, lighter Darker silver, metallic. heavier Bronze, metallic, heavier
B. Numerical Data Sample A B C D
Mass (g) 65 26.9 55.5 63.2
# of moles 1 1 1 1
# of atoms 6.022x10^23 6.022x10^23 6.022x10^23 6.022x10^23
Identity of Element Zinc Aluminum Iron Copper
V. Analyze and Conclude 1) The mass is what led me to the determination of each element. 2) The masses were different even though each element was exactly one mole because different atoms of different elements weigh a different amount, which led us to determine the elements by their masses. 3) Determine the actual mass of a single atom of each sample: Sample A B C D
Mass of Atom 1.1 x 10^ -22 g 4.47 x 10^ -23 g 9.22 x 10^ - 23 g 1.05 x 10^ -22 g
4)
In this lab, we were able to figure out the identities of each sample of moles by finding out their masses. To begin with, we observed their physical properties (i.e. how heavy, what color ‌). After doing so, we weighed them on the balance to find out their masses. Once weighed, we were able to figure out what element they were composed of by looking at the Periodic Table of Elements. By observing their physical properties and figuring out their masses, we were able to determine what element all the samples were. By completing this experiment, I learned that there is an easy way to determine the element of a mole sample. It also led me to understand more about what a mole is. Not only were we able to find out what each sample was, but was also able to find out how many atoms were in each mole sample by dividing the mass by Avogadro’s Number. By matching up the masses we weighed to the correct masses for each element of the Periodic Table, we defined each sample with ease.