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Problem: Which of the white solids, labeled 1, 2, 3, and 4 is calcium chloride, citric acid, glucose, and calcium hydroxide.
Prediction/Hypothesis: If, we perform tests on a solution formed of the white solids and then test for conductivity, and effects on blue, and red litmus paper, then we should be to determine which of the solids in a solution forms and acid, base, is molecular and is ionic, because of the known properties of those types of solutions.
Variables:
Manipulated Variable: Solute
Responding: Conductivity, solubility, change in litmus paper.
Controlled: Amount of Water Added
Materials: red litmus paper
blue litmus paper
Ometer
beaker
scupula
stir stick
4 unknown white substances (solutes)
water
Procedure:
1. Use a scupula to take a small amount of solute and place it in beaker
add about 50 ml of water and stir with stir stick, record solubility.
2. Take stir stick and place a small amount of substance on red litmus
paper, record change if any, repeat for blue litmus paper.
3. Take Ometer and rinse with water record conductivity.
4. Repeat steps 1-3 for each substance, remember to rinse everything
thoroughly after done with each solution.
Observations:
Table 1
| Substance | Conductivity | Litmus Paper | Solubility |
| 1 | high | blue -> red | high |
| 2 | high | red -> blue | low |
| 3 | low | no change | high |
| 4 | high | no change | high |
Analysis:
Substance 1 is an Acid because it is ionic aqueous and turns blue litmus
paper red.
Substance 2 is a Base because it turns red litmus paper blue.
Substance 4 is a neutral ionic compound because it conducts and has
no effect on litmus paper.
Substance 3 is a molecular compound because it doesn't conduct and
has no effect on litmus paper.
Conclusion:
Based on the results and through analysis the classifications of each
substance are as follows:
Substance one is citric acid, because it is an acid which turns blue
litmus paper red and acids contain H+ ions.
Substance two is calcium hydroxide, because it turned red litmus paper
blue, indicating it was a base, and all bases contain OH- ions.
Substance three is glucose because it is a molecular compound and when
aqueous does not conduct electricity.
Substance four is calcium chloride, because it conducted electricity
and all soluble ionic compounds dissolve to create electrolytes.
Discussion:
A. Experimental Errors:
The fact that we were using the same beaker, stir
stick, Ometer over and over again, could of effected
our results if they were not clean thoroughly enough.
The fact that we were not using filtered water,
and that the water we were using could of had all kinds of solutes already
dissolved in it ,could of also effected our results especially the conductivity.
B. Extended Activities:
NA
