Chloride ion (Cl-）It is the - 1 valence ion of chlorine that widely exists in nature.Chlorine ion is an organismInternal contentThe richestanion, viaTransmembrane transportandion channelParticipate in various biological functions of the body.
In a chemical reaction, chlorine atoms get electrons, so that chlorine atoms participating in the reaction are charged.The charged chlorine atom is called chloride ion.[1]
purpose
Announce
edit
Chloride ions play various physiological roles.Many cells have chloride channels, which are mainly responsible for controllingQuiescent periodCellularMembrane potentialAnd cell volume.stayMembrane systemMedium, specialneuronThe chloride ion in can be regulatedglycineandγ - aminobutyric acidRole of.Chlorine ion also contributes to the maintenance ofacid-base balanceofThe kidney is an organ that regulates the content of chloride ions in the blood.The maladjustment of chloride ion transport will lead to somePathologyThe most familiar change is cystic fibrosis, which is caused byplasma membraneMutation of the last chloride transporter CFTR.
one
Add dilute nitric acid to the solution for acidification.
two
Add silver nitrate solution to the solution。
three
If no white precipitate is generated, there is no chloride ion;If any, filter the sediment and add sufficient concentrated ammonia water.
four
If the precipitation is insoluble, there is no chloride ion;If the precipitation is dissolved, dilute nitric acid is added to it.
Chlorine standard solution (1mg/mol): Reference for accurately weighing 1.6487g and drying at 270~300 ℃sodium chloridetoBeakerMedium, after dissolving with water, transfer into 1LVolumetric flaskMedium, diluted to the mark,Evenly mix, stored inPlastic bottleMedium.1mL of this solution contains 1mg of chloride ion (Cl-）；
Ammonium thiocyanate standard solution [c (NHfourCNS)=0.1mol/L〕: Dissolve 7.6g ammonium thiocyanate in water and dilute to 1L.
Calibrate the concentration as follows: accurately suck 5mL of chlorine standard solution into a 150mL beaker, add 5mL of nitric acidburetteAdd 8mL of silver nitrate standard solution, heat it, slightly boil it until the precipitation coagulates, slightly cool it, add 2mL of ferric ammonium vanadium indicator, titrate the excess silver nitrate with ammonium thiocyanate standard solution until pink color appears.SimultaneousBlank test。
Calculate the actual concentration of ammonium thiocyanate standard solution c (mol/L): c=m/0.03545×(Vzero－V）, where m is the mass of chloride ion in the chlorine standard solution taken;VzeroIs the volume of ammonium thiocyanate standard solution used in blank test (i.e. 8mL silver nitrate standard solution);VIs the volume of ammonium thiocyanate standard solution used for titrating excess silver nitrate standard solution;0.03545 is equivalent to 1.00 mL silver nitrate solution [c (AgNOthree）=1.000 mol/L].
Sulfuric acid highironAmmonium 〔 Fe (NHfour)(SOfour)two·12HtwoO] Indicator: Dissolved 40gAmmonium ferrate sulfateAdd about 2mL nitric acid in 100mL water to make the brown disappear.
Weigh 5g (accurate to 0.001g) of sample into a 100mL volumetric flask, add 50mL of water, shake for 10min, make chlorine completely leached, dilute with water to the mark, mix well, and dry filter.
precipitate
Accurately suck 50mL of the above filtrate into a 150mL beaker, add 5mL of nitric acid (1.3.1), use a micro burette to add 8mL of silver nitrate standard solution, heat it to slightly boil, to removeOxides of nitrogen, cooling.
titration
Add 2mL ammonium ferrate sulfate indicator, titrate the excess silver nitrate with ammonium thiocyanate standard solution until pink appears.
Result calculation: percentage content of chloride ion: chlorine (Cl%)=[（Vzero－V)c×0.03545/m] × 100, whereVzeroIs the volume of ammonium thiocyanate standard solution used in blank test (i.e. 8mL silver nitrate standard solution);VIs the volume of ammonium thiocyanate standard solution used to titrate the sample;cIs the concentration of ammonium thiocyanate standard solution;0.03545 is equivalent to 1.00 mL ammonium thiocyanate solution [c (NHfourCNS)=1.000mol/L] chloride ion mass;M is the mass of the sample used for titration.
