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You are my Density!?

Introduction:

Chemical and physical properties are used to distinguish between substances and identify unknown substances. Physical properties depend upon the substance itself. They are observed with no change in chemical composition of the substance. Color, boiling point, state of matter, and density are physical properties. Chemical properties describe the characteristics that depend upon the way a substance reacts with other substances. Chemical properties involve the chemical reaction of a substance (called a reactant) to form a different substance (called a product),

Evidence that a new substance has been formed as a result of a chemical change may include: a color change, a solid is formed (called a precipitate), a gas forms (fizzing), a new odor produced, temperature change, or light produced.

Part A

Purpose:

To identify chemical and physical properties of different substances by using specific identification tests and to use this skill and knowledge to identify unknowns.

Materials:
 
Known Solutions Test Materials
Spot plate copper (II) sulfate (CuSO4) 4 pieces of magnesium metal
Magnifying glass hydrochloric acid (HCl) 4 pieces of copper
silver nitrate (AgNO3) 4 pieces of iron
sodium hydroxide (NaOH) 4 pieces of pH paper
salt solution (NaCl)

Procedure:

The data recorder should copy the data tables from the overhead.

Observe each of the four known solutions. Record as many readily observable physical properties as possible for each.

Repeat step #2 for the five test materials.

Draw a diagram of the spot plate on at least half a sheet of paper. Use this to identify each test performed.

Have your teacher approve your data before continuing.

Magnesium ID Test: Place four pieces of magnesium into four spots on the spot plate. Add just enough of each known solution to each piece of magnesium so that it is completely covered. Record your observations pertaining to the properties and any changes of each spot.

Copper ID Test: Place four pieces of copper into four spots on the spot plate. Add enough of each known solution to each piece of copper so that it is completely covered Record your observations pertaining to the properties and any changes of each spot.

Iron ID Test: Place four pieces of iron into four spots on the spot plate. Add enough of each known solution to each piece of iron so that it is completely covered. Record your observations pertaining to the properties and any changes of each spot.

Salt solution ID Test: Add about 5-10 drops of each known substance to four of the spots. Add 2-3 drops of the salt solution to each spot, waiting one minute between each. Record your observations pertaining to the properties and any changes of each spot.

pH Test: Place a pH paper in four different spots. Record original color of paper. Add one drop of each known substance to the four pH papers and observe/record the paper’s color.

Have your teacher approve your data before continuing.

Dispose of the reaction materials according to your teacher’s instructions. Do not just rinse down the sink!?

Part A Analysis:

Open the file atomlab.doc. Type the answers in red. Save to your period’s folder as atomlab analysis

Make a table listing the terms used in your observations in the first column. Determine the following about each term in subsequent columns: Determine whether each was an observation or an interpretation.

Identify which were physical properties and which were chemical properties.

Determine intensive and extensive properties. (check your notes)

Have your teacher approve your table before continuing.

For each test performed, identify whether there were chemical, physical, or both types of changes.

What evidence (see introduction) supports your identification of each chemical change listed in #2?

Using a pH color chart, determine the pH of each known substance and whether it is an acid, base, or neutral substance.

Have your teacher approve your analysis before continuing.

Part B

Preliminary Questions:

If you have various samples of matter and each sample has the same mass, (a) the sample with the smallest volume will have the _________ density; (b) the sample with the largest volume will have the ______ density.

If you have various samples of matter and each sample has the same volume, (a) the sample with the smallest mass will have the ______ density; (b) the sample with the largest mass will have the ______ density.

Materials:

Sample Set I and/or Set II water triple beam balance

Graduated cylinder ruler

Procedure:

Your teacher will assign Task 1 and/or Task 2

Task 1

Obtain Sample Set I. All samples of this set should have the same mass.

Determine the mass of each sample by using the triple beam balance. Record these masses in a data table.

Measure and record the hieght (h) and the diameter (d) of each sample in centimeters.

Determine and record the volume of the tallest sample by the water displacement method. Put enough water in the graduated cylinder so that the sample will be completely submerged when placed in the cylinder. Measure and record this volume of water. Tilt the graduated cylinder and slide the sample down the side of the cylinder. Be careful not to let the sample drop into the cylinder, glass breaks. Measure and record the new volume of the water and the sample together. To determine the volume of the sample, find the difference between the two measured volumes.

Repeat step #4 for each sample.

Have your teacher approve your data before continuing.

Return Sample Set I, the triple beam balance, the graduated cylinder, and water container.

Task 2 Obtain Sample Set II. All samples of this set should have the same volume.

Determine the mass of each sample by using the triple beam balance. Record these masses in a data table.

Measure and record the hieght (h) and the diameter (d) of each sample in centimeters.

Determine and record the volume of one sample (not Sample "C") by the water displacement method as described in Part 1 step #4.

Have your teacher approve your data before continuing.

Return Sample Set II, the triple beam balance, the graduated cylinder, and water container.
 
 

Part B Analysis: Open your file atomlab analysis . Type the answers in red. Save to your period’s folder as Final atomlab analysis Calculate the volume of all samples in both sets based on the h and d measurements. The volume of a cylinder is simly the area of the circle multiplied by the height of the cylinder. Each group member should show K-U-E-S for one sample, the manager should do any that remain.

Compare both values of volume you found for each sample. (1 mL = 1 cm3) (a)Which do you feel is more accurate? Why? (b)Which is more precise? Why?

Have your teacher approve before continuing.

Determine the density of each sample and record in your data table. Make note of which volume measurement you chose to use and why it was used. Each group member should show K-U-E-S for one sample, the manager should do any that remain.

Use the table of densities provided to you to determine a possible identity of each sample. Record the identity of each sample.

Have your teacher approve before continuing.

If you have various samples of matter and each sample has the same mass, (a) the sample with the smallest volume will have the _________ density. Why? (b) the sample with the largest volume will have the ______ density. Why?

If you have various samples of matter and each sample has the same volume, (a) the sample with the smallest mass will have the ______ density. Why? (b) the sample with the largest mass will have the ______ density. Why?

Would you consider density to be a property which was dependent on the structure of the matter (intensive) or simply on the amount of the matter (extensive)? Explain.

Have your teacher approve before continuing.
 
 
 
 

Group Report Cover Sheet Title, group, group members/duties, date, class period Group Work (put this in order as close as you can, be sure everything is clearly labeled) Data o Part A: Data Tables

o Part B: Data Table(s)

Individual Report Cover Sheet

Title, name, group, date, class period

Individual Work

Preliminary Questions

Part B : Analysis #1, #4

Conclusion

Part A – Your group has been given the four known solutions in unlabeled bottles, describe how you would correctly identify each solution.

Part B - Briefly and completely, discuss your answers to the preliminary questions. Basically you are re-answering the preliminary questions, only now you have experimental evidence to support your answers, so an explanation is needed. Be sure to specifically mention when you have changed your answers.

Evaluation

Write an evaluation of your group’s performance during this lab activity. Specifically address each group member‘s performance of his/her specific job.(1 - 2 paragraph(s)

Write an evaluation of the lab activity itself (1 paragraph).

Please provide specific and useful information, not just, “I liked my group….this was a fun lab….”. Also, remember to include supporting evidence for your evaluation, this is a science class not a daytime talk show.