SCH3U
Investigating the Alkali Metal and Alkaline Earth Metal Families
Name:______
Partner(s):______
Date completed:______
Date due:______
Date submitted:______
Introduction:
A family is a column or group of elements on the periodic table where the elements share similar properties. The alkali metal family is group 1 on the table whereas the alkaline earth metal family is group 2. In this investigation you will be studying elements from these families to determine some of the properties of each family and compare the two families for similarities, differences and trends in chemical reactivity. On the first day of the lab the Alkali Metals will be studied and on the second day of the lab the Alkaline Earth metals will be tested and a gas test will be performed.
Materials:
- face shield
Revised S14
SCH3U
- 250 mL beaker
- wire gauze
- dry tweezers
- pH paper and pH scale
- 2 test tubes
- Bunsen burner
- test tube holder
- wooden splint
- phenolphthalein indicator
- Samples of magnesium, calcium, lithium, sodium, and potassium
Revised S14
SCH3U
Safety:
*Make sure the lab benches are DRY at all times.
*Do not touch any of the metals with your hands- the moisture on you hand is enough to cause a reaction.
*Stay on the OUTSIDE of the side lab benches, and do not go behind the front lab bench for any reason.
*If you drop a piece of metal on the floor, find it immediately and tell your teacher.
*A face shield must be worn for some of the reactions.
*Any paper towel that has touched the metals should be soaked with water in the sink before it is put in the garbage can to make sure all metal has reacted.
* Dispose of used Mg in metal waste bucket.
*Dispose of any liquids in the waste beakers in the fumehood.
Method:
__ 1. Place a check mark in the space provided as you read or complete each step of the activity.
__ 2. Carefully read over the lab procedure to familiarize yourself with the procedure. Design three data tables to record your lab results. Pay close attention to proper table design (units in headings only, descriptive title, ruler used, decimals aligned, separate tables for chemical and physical properties etc.) . You are not allowed to copy your data table out again to make it neater. Do it right the first time and write in pen in your lab book as you make observations. A scientist needs to be able to prove that what is written in a lab report is exactly what was seen in the lab. You may do your calculations and write up in pencil but the observations must be in pen.
__ 3. You must wear a face shield when working with Li, Na and K. You must wear a face shield or safety glass when working with Mg and Ca. Your eyes must be protected at all times during the lab. Follow your teacher’s instructions. Make sure your glassware is CLEAN and DRY before you start each test. Gather all of your materials (except the metals) at your lab station before you begin.
------Part 1TEACHER DEMO------
LITHIUM
__ 4. Wearing a face shield bring a DRY beaker with a piece of paper towel in it to the front. Using the tweezers, place a small piece of lithium metal onto the paper towel. Very CAREFULLY return to your station.
__ 5. Describe three physical properties of the metal in Table 1. Try and determine the softness of the metal using the tweezers.
__ 6. Half fill the clean 250 mL beaker with tap water. Record the physical properties of the water in Table 1. Check the pH of the water before the reaction and record it in Table 2.
__ 7. Have a piece of wire gauze with ceramic in the middle ready to cover the beaker. Drop the metal into the beaker of water and IMMEDIATELY cover the top of the beaker with the wire gauze.
__ 8. Describe what happens in Table 2.
__ 9. After several minutes remove the wire gauze, test the pH, and record in Table 2.
SODIUM
__ 10. Wearing a face shield rinse out the beaker at your station and then repeat the procedure steps 14 – 19 for the sodium metal.
POTASSIUM
__ 11. Wearing a face shield rinse out the beaker at your station and then repeat the procedure steps 14 – 19 for the potassium metal.
CLEAN UP
__ 12. When finished, put all of the paper towel used in the sink and soak it with water for 30 seconds before you throw it in the garbage. This ensures that there are no unreacted metal pieces in the garbage.
__ 13. Clean up you area, wash all glassware. Dispose of the used pH paper in the garbage and the used magnesium strip in the metal salts waste bucket. Put away all of the lab equipment and then return to your lab area and wipe the lab bench with a moistened paper towel.
------Part 2 STUDENT LAB------
MAGNESIUM
__ 4. Obtain a small strip of magnesium metal. Describe the physical properties (colour, clarity, state, hardness) of the magnesium metal before the reaction. Record your observations in Table 1.
__ 5. Fill a test tube one third of the way full of tap water. Test the pH of the water by dipping the pH paper into the water using the tweezers. Record the pH before the reaction in Table 2.
__ 6. Light a Bunsen burner. Add the magnesium strip to the test tube filled with water and gently heat the test tube using the test tube holder and making sure you move the test tube in a circular motion in and out of the flame. Be careful it does not boil over. Remove it from the flame if it starts to boil rapidly. Be sure to point the test tube towards the middle of the room (away from others and yourself) as you heat it.
__ 7. Remove the test tube from the flame. Can you see any evidence of a chemical reaction occurring along the surface of the magnesium during the reaction? Look closely and record your observations (colour, clarity and state of Mg and of liquid) in Table 2.
__ 8. Continue heating the magnesium gently for 3 minutes.
__ 9. Check the pH again after the experiment by placing 2 drops of the phenolphthalein indicator in the test tube and record the colour in your observations in Table 2. (colourless indicates an acidic solution and pink indicates a basic solution)
CALCIUM
__ 10. Obtain 1 lump of calcium metal in a small DRY beaker and return to your station. Describe three physical properties of the calcium metal before the reaction in Table 1.
__ 11. Quarter-fill a 250 mL beaker with tap water and test the pH of the water with the pH strip. Record the pH before the reaction in Table 2. COLLECT GAS for the GAS TEST NOW! (Instructions below)
__ 12. Drop the lump of calcium into the beaker of water. Record your observations in Table 2.
__ 13. Look closely, does the water look different in any way? After the reaction is complete, check the pH and record your observations in Table 2.
GAS TEST
To identify the gas being released in these reactions, you will perform a gas test and record your observations in Table 3. The same gas is produced in all reactions in this lab so only one gas test is needed (use Ca and water reaction).
__ 22. Fill a 250 mL beaker about half full of water.
__ 23. Fill one of the test tubes with water and place a small piece of paper towel over the end. While holding your finger over the end to hold the water in, invert the test tube into the beaker and remove the paper towel. You should now have an upside down test tube full of water in the beaker of water.
__ 24. Obtain 2-3 lumps of calcium metal in a small beaker and return to your station.
__ 25. Drop one lump of calcium into the beaker of water and quickly manoeuvre the test tube over top of the piece of calcium to collect the gas bubbles being released. Add a second and later a third lump to collect more gas and continue to fill the test tube with gas (the water level in the test tube will lower as the gas fills it up). You should now have an upside down test tube full of gas in the beaker of water.
__ 26. Get a burning splint ready. Turn the test tube upright and wait about 4 seconds. Bring a burning splint into the mouth of the test tube. Record what happens in Table 3.
CLEAN UP
__ 27. When finished, put all of the paper towel used in the sink and soak it with water for 30 seconds before you throw it in the garbage. This ensures that there are no unreacted metal pieces in the garbage.
__ 28. Clean up you area, wash all glassware. Dispose of the used pH paper in the garbage and the used magnesium strip in the metal salts waste bucket. Put away all of the lab equipment and then return to your lab area and wipe the lab bench with a moistened paper towel.
Lab Report Details
Include all sections on the rubric in your lab report.
For Observations
Data tables should have a specific title and be organized in a logical fashion.
Table 1. – Include the physical properties of the five metals(colour, clarity, state, texture, lustre…)
Table 2. – Include the chemical properties of the five metals (reactivity, pH values…)
Table 3. – Include the gas test observations.
For Results Summary
Include a results summary paragraph which summarizes the basic trends of the lab. State what you observed, do not explain why you observed what you did. Consider:
a) The physical properties of the alkali metals and alkaline earth metals. What do they have in common and how do they differ? What is the trend in physical properties across and down the periodic table?
b) The chemical reactivity of the alkali metals and alkaline earth metals. What do they have in common and how do they differ? What is the trend in reactivity across and down the periodic table? Rank the metals from least reactive to most reactive.
For Discussion
Write a discussion in paragraph form that attempts to explain your observations. You may need to do some research. Consider:
a) Why do these elements share certain physical properties and chemical properties?
b) Attempt to explain the reasons for the trends in the results as stated in the results summary. Consider the trends of the periodic table discussed in class. Why are some more reactive than others? Be specific when you explain.
c) Explain the pH changes and gas test. What do these mean for the reactions of these metals with water? What are the products?
Investigating the Alkali Metal and Alkaline Earth Metal Families Lab Rubric
Minimal requirements are met / Level 2
Some of the requirements are met / Level 3
Most of the requirements are met / Level 4
All of the requirements are met
Communication
Title Block and Rubric
- appropriate title
-name and partner(s) name(s)
-date lab performed
-date lab due
-rubric is submitted with lab / /4
Purpose and Materials
-Appropriate general purpose is given in one or two sentences
-Materials being tested are mentioned in the purpose / /3
Materials and Methods
- write ‘Refer to lab sheet.’ / /1
Observations (Data Tables)
- appropriate title at the top
- well organized and neat
–numbers are aligned
- units are in the headings only / /4
Observations (Data Tables)
- contain detailed observations / /8
Results Summary
each significant result is summarized / /12
Overall Communication
-Overall clarity, use of conventions, vocabulary, terminology / /4
Overall Communication /36
Inquiry
Experimental Technique
- accuracy of the results
-safety in the lab / /4
Discussion
- all results are explained in an in depth manner
- discussion is in a logical sequence / /12
Overall Inquiry /16
Table 1:
Metal / Before Reaction with Water / After Reaction with WaterMg
Ca
Li
Na
K
Table 2:
Metal / pH Before Reaction with Water / Observations During Reaction / pH After Reaction with WaterMg
Ca
Li
Na
K
Revised S14