reaction between sodium sulphite and dilute sodium hypochlorite??
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Expt EX1Exothermic Reaction(EX)ObjectiveThe purpose of this experiment is to determine the enthalpy change ∆H (kJ/mol) for the reactionNaClO(aq) + Na2SO3(aq) => NaCl(aq) + Na2SO4(aq) + heatThe exothermic reaction of sodium hypochlorite (bleach) with sodium sulfite produces heat. Heat and heat capacityIn this experiment, you will use a digital temperature probe to monitor the temperature changes, ∆T, during the course of (Part I) the chemical reaction reaction and (Part II) resistance heating. In Part II you will increase the temperature of the system using an electrical heater to determine the constant pressure heat capacity, Cp, of the solution. Determining qheating and ∆Theating gives Cp from Cp = ( qheating / ∆Theating )(1)In Part I you will use the Cp determined from Part II and the measured ∆Treaction to determine ∆H from value for heat released by chemical reaction (qreaction) whereqreaction = – Cp ∆Treaction(2)The negative sign is necessary because if heat is absorbed by solution then ∆Treaction is positive and then the qreaction must be exothermic and negative. The heat released by reaction (q is -) is the same heat absorbed by solution (q is +).Caution and SafetyKeep all chemicals away from electronic devices. Undiluted bleach is irritating to the skin and harmful to eyes. Wash your hands after working with the NaClO solutions.
Expt EX2Procedure - Part I Chemical ReactionPrepare 500mL of 0.400M sodium sulfite (Na2SO3) solution. Use a magnetic stirrer to help dissolve quickly and completely. Get a 50ml pipet ready so you can add sodium sulfite solution to the reaction beaker.Prepare 500mL of 0.300M sodium hypochlorite solution by diluting Chlorox bleach with water. Chlorox bleach is 6.00% by weight NaClO, and it has a density of 1.07 g/mL. Get a 100ml graduated cylinder ready to add NaClO solution to the reaction beaker. Do dilution calculations before you come to lab.You are going to add the two reactants to the reaction beaker and use the digital temperature probe to monitor the temperature as a function of time.Using the graduated cylinder, place 100mL of the NaClO solution into the reaction beaker (a 250mL beaker covered with cotton and tape for insulation). Place a stir bar in the bottom of the beaker, and position the large cork or rubber stopper onto the beaker so that the resistor heater and temperature probe are in position. Stir the solution slowly with the magnetic stirrer, making certain that the probe does not touch the bar or the resistor heater. Wait about a minute to allow time for solution temperature to equilibrate and then begin taking temperature readings (set at about 5second intervals). You need at least 60 seconds of temperature readings to make sure that the initial temperature has equilibrated to a constant value and is not changing. While the temperature readings continue to be automatically collected, you will add solution observe temperature change.Using the pipet, add exactly 50mL of the sodium sulfite solution through hole in middle of the stopper. You should see the temperature increase. Continue taking temperature readings for at least 60 seconds after the maximum temperature is reached. Observe your graph of temperature versus time, and determine the initial temperature and final (highest) temperature of the reaction system. Show the lab instructor this graph on the computer screen for the first reaction so it can be checked prior to continuing.
The reaction between sodium sulphite and dilute sodium hypochlorite is Na₂SO₃ + 2HCl → 2NaCl + H₂O + SO.
- When the reaction between Sodium Sulphite and Dilute Sodium Hypochlorite takes place, there is a release of chlorine or other noxious gases.
- Moreover, reducing agents are used such as: - Sodium Sulfite, Sodium Bisulfite, Sodium Hydrosulfite, and Sodium Thiosulfate.
- The evolution of heat may cause splashing or boiling during the reaction process.
- Moreover, Sodium Hypochlorite reacts readily with Hydrogen Sulfide.
- The reaction converts the sulfide ion into free sulfur in a neutral or acid solution and lastly to the sulfate ion in an alkaline solution.
- However, Sodium Hypochlorite can be generated on-site by processing geothermal brine occurring in electrolytic cells.
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