I already did everything I just need to answer these questions. The Conclusion q

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I already did everything I just need to answer these questions. The Conclusion questions

lab report for Exp: Electrical Conductivity of Aqueous Solutions.

EQUIPMENT and CHEMICALS conductivity apparatus small, dry beakers (6) sodium hydroxide, 0.1 M NaOH . glass stirring rod ammonium hydroxide, 0.1 M NH4OH .wash bottle with distilled water potassium iodide, 0.1 M KI . sodium chloride, solid NaCI aluminum nitrate, 0.1 M AI(NO3)3 magnesium hydroxide, sat'd. Mg(OH)2 calcium carbonate, solid CaCO3 copper(II) sulfate, 0.1 M CuSO calcium chloride, solid CaCl2 calcium nitrate, 0.1 MCa(NO3)2 hydrochloric acid, 0.1 M HCI nitric acid, 0.1 M HNO sulfuric acid, 0.1 M H2SO4 barium hydroxide, 0.1 M Ba(OH)x2 e straw . acetic acid, 0.1 M HC2H302 PROCEDURE A. Conductivity Testing-Evidence for Ions in Aqueous Solution Note: Rinse the electrodes with distilled water after each conductivity test. Record your observations in the Data Table, and state whether the conductivity test indicates a strong electrolyte or weak electrolyte. (Write strong electrolytes as ions and weak electrolytes as molecules refer to the LiOH and HNO2 examples in the Data Table.) 1. Pour about 25 mL of distilled water in a small dry beaker and test the conductivity. le Pour about 25 mL of tap water in a small dry beaker and test the conductivity. 2. Place about 0.5 g of solid NaCl in a small dry beaker and test the conductivity. 3. Place about 0.5 g of solid CaCO3 in a small dry beaker and test the conductivity. 4. Place about 0.5 g of solid CaCl2 in a small dry beaker and test the conductivity 5. Test the conductivity of each of the following in a small beaker Add distilled water, stir, and retest the conductivity. Add distilled water, stir, and retest the conductivity Add distilled water, stir, and retest the conductivity. (a) 10 mL hydrochloric acid, 0.1 M HCI (b) ~10 mL acetic acid, 0.1 M HC2H302 (c) 10 mL nitric acid, 0.1 M HNO3 (d) ~10 mL sodium hydroxide, 0.1 M NaOH (e) 10mL ammonium hydroxide, 0.1 M NH4OH (f) ~10 mL potassium iodide, 0.1 M KI (g) ~10 mL aluminum nitrate, 0.1 M Al(NO3)3 (h) ~10 mL magnesium hydroxide, saturated Mg(OH)2 (i) ~10 mL copper(II) sulfate, 0.1 M CuSO4 G) 10 mL calcium nitrate, O.1 M Ca(NO3)2 RECYCLIE Chemical Waste

Explanation / Answer

1. Whether an aqueous solution is electrically conducting or not depends upon factors like the presence of ions in the solution.

Increase in the number of ions in solution would increase the number of charge carriers and hence increase the conductivity of the solution. However not all aqueous solutions contain ions, for eg. NaCl solution is a electrically conducting but a solution of sucrose is not since a sucrose solution does not contain free ions. No free ions implies no charge carriers and hence it does not conduct electricity at all.

2. Electrolytes are substances that dissociates into ions in solution due to which conductivity is brought about in the solution. Strong electrolytes are those which dissociate completely into ions hence conduct electricity well and makes a light bulb glow strongly. Eg. NaCl solution.

On the other hand, weak electrolytes are those which do not dissociate completely into ions, rather exist majorly as neutral molecules in solution hence do not conduct electricity well and makes a light bulb glow dimly. Eg. NH4OH solution.

In the solid state ions would not be able to move around freely like in aqueous or liquid state due to which conductivity would be poor. Eg. solid NaCl. Only molten and aqueous NaCl conducts electricity, solid NaCl is a non- conductor of electricity.

3. The factors are the presence of ions in solution, mobility of the ions. More the mobility, better charge carriers they are and hence make a solution more electrically conducting. Eg. H+ and NH4+ are ions produced from HCl and NH4OH. But both HCl and NH4OH are not equally conducting. The mobility of H+ is far more than that of NH4+ which makes HCl a very strong electrolyte and NH4OH, a weak electrolyte.

4. A chemical reaction may or may not change the electrical conductivity. But in most cases it changes the conductivity.This is because the total concentration of ions get affected when a chemical reaction happens, and an increase or decrease in the total concentration of ions would bring about a change in conductivity.

5. In the first reaction we see that, NH4OH is a weak electrolyte due to the poor mobility of NH4+ as discussed above due to which bulb glows dim. HC2H3O2 also is a weak electrolyte since it is a covalent compound and gives no free ions in solution. When mixed, we get NH4C2H3O2 which does not dissolve in water to give ions, hence is a weak electrolyte. So here the individual solutions were weak electrolytes and even on mixing we get a weak electrolyte.

However in the second reaction, H2SO4 being a strong electrolyte due to the presence of H+ ions makes a bulb glow strongly. But Ba(OH)2 is a weak electrolyte due to its incomplete dissociation into ions. When mixed we get BaSO4, which dissociates into ions in water and hence is strong electrolyte and makes the bulb glow bright. So here the conductivity changes on mixing which indicates that a chemical reaction has occured.

6. Weighing and measuring samples, Testing the conductivities of solutions were learnt here.

7. Conductivity testing can be done to test to what extent dissolved ionic solids have been removed from sea water and has been made pure and fit for drinking. (Used in the process of de-salination of sea water).

Conductivity testing can also be done to check the accumulation of ionic solids in boilers and hence can be cleaned from time to time after having periodic quality checks.

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