Analysis section: one question per week (September 26 – October 2)
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1. Please hide your replies; editing after posting is invalid! Delete directly without hiding! 2. Hiding method: http://bbs.hcbbs.com/thread-492556-1-1.html 3. There is a reward for everyone who participates. Those who have suggestions for topics can post replies at http://bbs.hcbbs.com/thread-899447-1-1.html; a reward will definitely be given, and an additional 20 points will be awarded if the suggestion is adopted. This week's question: Into which categories can volumetric analysis be divided based on different types of reactions? Please provide examples (preferably ones from your own analysis laboratory; if not, use your knowledge to come up with examples).
Titration methods: four types – direct titration, indirect titration, back-titration, and displacement titration. There are also those classified by reaction type: acid-base titration, precipitation titration, complexation titration, and redox titration
Recalling chemical knowledge, the types of reactions include: acid-base reactions, redox reactions, chelation coordination reactions, and reactions that result in the formation of precipitates
Reply 1# *ngguanglueguo: Acid-base titration, redox titration, titration in non-aqueous solutions, sodium nitrite titration, iodometric method, complexometric titration, direct titration, and back-titration. I guess that’s roughly how it is in general
Volume analysis can be divided into four major categories based on the type of reaction: acid-base titration, redox titration, volumetric precipitation, and complexometric titration. The standard solution is added drop by drop from a burette to the test solution containing the substance to be analyzed, until the added solution reacts completely with the substance according to stoichiometric proportions. The amount of the substance to be analyzed is then calculated using the concentration and volume of the standard solution. The reaction formula is aX + bR = cP, and the formula for calculating the concentration of the substance being measured (X) is Cx = CRVR / Vx · a / b. In the formula, CR and VR represent the concentration and volume of the standard solution, respectively ； Cx and Vx represent the concentration and volume of the substance being tested, respectively ； a/b represents the metric relationship between X and R. During my previous graduation project, I carried out acid-base titration, using a standard NaOH solution to titrate the sample; the amount of standard solution consumed was used to determine the content of acidic groups in the sample. Issues to note: The standard NaOH solution prepared as required needs to be calibrated before each titration. This is because NaOH has a low molecular weight and strong water absorption, which results in significant errors during preparation and weighing; generally, potassium hydrogen phthalate is used for calibration ； The titration process requires considerable patience and great care; determining the endpoint is very important.
Acid-base titration, precipitation titration, complexometric titration, redox titration
Depending on the type of reaction between the standard solution and the substance to be analyzed, titrimetric analysis is divided into: 1 Acid-base titration H+ + OH‑ →H₂O 2 Complexation titration Zn²+ +H₂Y²- →ZnY²－+2H+ 3 Redox titration Cr₂O7²-+6Fe²++14H+ →2Cr3++6Fe3++7H₂O 4 Precipitation titration Ag+ + Cl－→Ag↓
Four types: 1. Direct titration method； 2. Indirect titration method ； 3. Back-titration method ； 4. Displacement titration method ；
Reply 1# *ngguanglueguo: Titration methods are classified according to the reaction type: acid-base titration, precipitation titration, complexometric titration, and redox titration
Acid-base titration, precipitation titration, complexometric titration, redox titration
Acid-base titration, precipitation titration, complexometric titration, redox titration