Question

please show the work

Prelab for Experiment 5 - Conductivity and Chemical Reactions 2.34E-4. The 'E' must be capitalized." Scientific notation format The prelab questions mirror those that you will be doing at the end of the experiment. Bring your work for this prelab assignment to lab and you will have a much easier time completing the Data Analysis Sheet at the end of the experiment. Student information Enter your name (first and last) and the last 4 digits of your student number Name: Number 1. The conductivities (in microsiemens per centimetre) for several 0.050 M solutions were measured, and the results are shown in the table 1 below. Classify each solution as either a strong, weak, or nonelectrolyte. Background information on electrolytes is located at the beginning of the experiment in your coursepack. Hint Table 1: Conductivities of various 0.050M solutions (e) | Chemical formula Conductivity Type of electrolyte elec Name HNO2 713 Select an answer nitrous acid 45 Select an answer ethanol 5717 Select an answer AgNO2 silver nitrate 8809 Select an answer ▼ MgCl2 magnesium chloride 2. Which one of the following is not a possible reason for a nonelectrolyte solution to have a conductivity greater than zero? Improper calibration of the conductivity probe 2. Which one of the following is not a possible reason for a nonelectrolyte solution to have a conductivity greater than zero? Improper calibration of the conductivity probe O Impurities in the container or solvent O The adsorption of carbon dioxide from the atmosphere Temperature fluctuations 3. How many moles of ions are produced when one mole of solid magnesium chloride dissolves in solution? Hint 4. What are the reaction products (ions) formed when solid potassium bromide is dissolved in water? Use the following formatting (no spaces before or after) and ensure that the capitalization and charge on the ion is correct Na+, Ca2+, F., OH-, S2-etc. You do not need to enter the phase. KBr → ? product 1 product 2- 5. If equal volumes of the nitrous acid and ethanol solutions were mixed, what value would you expect for the conductivity of the resulting mixture? Assume no chemical reaction occurs. Hin uS cm 6. If equal volumes of the 0.050 M silver nitrate and magnesium chloride solutions were mixed, and a chemical reaction occurred producing solid silver chloride, would the conductivity of the solution after the reaction be greater than, less than, or equal to the value expected of no precipitation reaction had occurred? Ogreater than Oless than Oequal

Answer 1

1.)

• Strong Electrolytes : Those electrolytes, which ionize completely in aqueous solution. Strong acids and strong behaves as strong electrolytes.
• Weak Electrolytes : Those electrolytes which does-not ionize completely in aqueous solution. Weak acids and weak bases behaves as weak electrolyte
• Non- Electrolyte : Those electrolyte which does - not exist in ionic form in aqueous solution For example : Ethanol, glucose and many more such type of compounds.

Let us classify given compounds as strong weak or non electrolytes :

HNO₂ : It has a medium conductivity value that is 713$\mu$S/Cm. Thus it will produce lesser ions in the solution. Conductivity is directly proportional to the number of ions produced in aqueous solution. As it is not producing much ions, so it will behave as a weak electrolyte.

C₂H₅OH : It has a low value of conductivity that is 45$\mu$S/Cm. Thus it will not produce ions in the aqueous solution and hence it will behave as a non-electrolyte.

AgNO₂ : It has higher value of conductivity that is 5717$\mu$S/Cm. Thus it will dissociate in the form of ions in aqueous solution and thus it will behave as a strong electrolyte.

MgCl₂ : It has highest value of conductivity among all other compounds that is 8809$\mu$S/Cm, thus it will dissociate in the form of ions in aqueous solution and thus it will behave as a strong electrolyte.

2.)

• If the probe is not perfectly caliberated, it will not show accurate conductivity measurment. Accurate caliberation helps us to be sure that our solution is not contaminated. We should use fresh caliberation solution everytime we caliberate.
• Impurities in Container or Solvent : Because of the impurities present in the solution, solution will show some conductivity thus it could be the reason of a non- electrolyte solution of showing more then zero conductivity.
• Temperature fluctuations : More the temperature, faster will be the movement of ions present in the solution and hence more will be the conductivity.

       Hence Adsorption of CO₂ from the atmosphere could not be the reason of a non-electrolyte to have conductivity             greater then zero

3.)

When solid Magnesium Chloride is dissolved in water, It dissociates itself into Mg²⁺ and Cl^- ions as shown in the reaction given below :

MgCl₂$\rightarrow$ Mg²⁺ + 2Cl^-

Thus 1 Mg²⁺ and 2Cl^- ions are formed, that is 1 mole of Magnesium ions are formed and 2 moles of chloride ions are formed , when 1 mole of MgCl₂ is dissociated. Thus total 3 moles of ions are formed.

4)

When potassium bromide is dissolved in water, it dissociates into K⁺ and Br ^- ions and the reaction is shown below:

                                                      KBr $\rightarrow$ K⁺ + Br ^-

thus product 1 = K⁺

and product 2 = Br ^-

5.)

Nitrous acid is the weak electrolyte and ethanol is a non- electrolyte, and from the unit of conductivity it is clear that the conductivity here is the specific conductivity.

Now as the solution of Nitrous acid is diluted with ethanol, then number of ions per unit volume that carry current in the aqueous solution decreases and hence the specific conductivity is decreased when equal volume of ethanol and Nitrous acid are mixed.

6.)

The reaction between silver nitrate and MgCl₂ is shown below :

AgNO₃ + MgCl₂$\rightarrow$ AgCl + Mg(NO₃)₂

Conductivity of the solution after the reaction will increase because Size of Mg²⁺ ions are lesser as compare to the size of Ag⁺ ions (more the charge, lesser will be the size of ion), here Mg²⁺ is replacing Ag⁺ from it's salt solution. Thus conductivity of the solution will increase.