How the variables were controlled in the experiment:
- Have good eyesight when recording the data.
- Use the same materials.
- Keep all equipment on same table
The safety precaution in the experiment:
- Be careful when handling the glass.
- Do not eat any chemicals.
- Do not any chemicals
- Be careful with the Bunsen burner
The procedure of the experiment:
- Using the spoon provided in the lab, add about 0.01 g of magnesium oxide to one of the three test tubes.
- Add 10 mL of distilled water to the test tube with the magnesium oxide.
- Place the cork on the test tube and use dapping to stir the solution.
- Observe the characteristics of the substance and record the data.
- Using the pipette and the pH paper, determine the pH value of the mixture and record the data.
- Record all the data and observations.
- Repeat steps 1 – 6 for calcium hydroxide and barium hydroxide.
- Clean out the test tubes.
- Add 2 mL of barium chloride (solution of Ba2+ ions, concentration 0.1 M) to each of the test tubes.
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Label each of the test tubes with Na2CO3, Na2SO4, and NaOH respectively.
- Add 2 mL of the substances listed in step 10 to each of the matching test tubes.
- Record the observations and data.
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Repeat steps 8 - 9, and 11- 12 for calcium nitrite and magnesium sulfate.
- Collect the chloride test tubes and put them in a beaker filled with water.
Thermal Stability of the Carbonates
- Confirm set up of the device.
- Using the Bunsen burner, heat up the substance for around 5 minutes.
- Observe and record the data.
Data Collection and Processing:
- When you go down the group, energy to remove electrons decrease. Also the number of electrons increase, the atomic radius increase.
- The atomic radii increase as you go down since the number of electons in the outermost shell increase.
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The reaction of magnesium oxide with water is as follows:MgO + H2O → Mg(OH)2
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The reaction of calcium hydroxide with water is as follows Ca(OH)2 + H2O → Ca2+ + OH- + H2O
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The reaction of barium hydroxide with water is as follows Ba(OH)2 + H2O → Ba2+ + OH- + H2O
The Acid - Base Character across the group:
Data Table: The Properties of the group 2 Elements reacting with Water
- As you go down the group, the elements become more basic as it reacts with H20
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The reaction can be represented as : X + H2O → X+ + OH- + H2O
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Mg(OH)2 is also known as milk of magnesia. .
The trends in the Thermal Stability of the Carbonates:
The thermal decomposition is as follows: MgCO3 → MgO + CO2
When you go down the group the carbonates become more thermally stable.
Table 2: The Observations of Hydroxides, Sulfates, and Carbonates
As you go down the group, the hydroxides become soluble, while the opposite is true for the carbonates and sulfates.
Conclusion and Evaluation:
From the experiment, many trends were made based on the data collected. Trend include: As you go down the group, the hydroxides become soluble, while the opposite is true for the carbonates and sulfates.
Some improvements that could be made iclude, improving stirring, better eyesite, better notes, more accurate equipment. Limiations icluded, not enough time, wrongly transferring data, bad eyesight.
