Exercise Apparatus And Techniques, Exercises of Analytical Chemistry

Download Exercise Apparatus And Techniques and more Exercises Analytical Chemistry in PDF only on Docsity! A volume of 50.0 mL of solution X is to be added to another vessel. A student decided to use a 50.0 mL volumetric flask to measure out the volume of the solution X. State whether the correct measuring glassware has been used. i) State the function of a desiccator. ii) Name two desiccants that can be placed inside the desiccators. No , It is designed to contain an accurate volume . i ) A desiccator is used to keep samples dry while they are cooling and before they are weighed and , in some cases , to dry the wet sample . Ii ) Any two suitable desiccants i • calcium chloride • silica get • calcium sulphate • Distilled water - Distilled water is prepared using distillation process - Contains no dissolved menirals , chemicals & impurities - Removes more than 99.8% of most tap water impurities , Including Cryptosporidium • Deionized water - Deionized water is prepared using 10h - exchange process - contains of organic Impurities - Does not contain ion such as ca " . Na " , C1 - , Br - except 1-130 " & OH ? = Pipette • TC - to contain the specified volume * It pipette is labeled as tc , the small remaining volume should be shaken or blown out to obtain the correct amount of material . • TD - to deliver the specified volume at the calibration temperature . * If pipette is labeled as TD , a certain small volume will remain in the tip . this should not be shaken or blown out . 1) Insert the precisely weighed amount of substance , or rinse In a standard solution concentrate . a) Fill the flask with distilled water to about half . Swirl the flask to dissolve and mix the contents thoroughly . 3) Top up the flask with distilled water to just below the ring mark . 4) Top up the remaining volume , using a wash bottle or pipette , until the meniscus is exactly at the ring mark . Important : meniscus must be read at eye level . the wall of the flask must not be wetted above the mark . 5) Close the flask and shake upside down to mix contents . it A transfer pipette is designed to deliver a single fixed volume of solution such as 10mL , 20mL Or 25mL . ii ) Actual Volume of the pipet : 19-8509 ✗ 1.0030 mL = 19.909 mL g ' technical grade ' chemical reagets are of low purity therefore are not suitable for preparing standard solution . Standard solution should be prepared using primary standard chemical reagent Before using the analytical balance , it should be warmed up for at least half an hour - Before turning on , be sure that the doors are closed and the pan Is not touching the draft ring . Never hold objects to be weighed by hand / finger . Use tongs . Dust pan lightly before and after weighing object . Center load as well as possible . Never weigh heated objects . Allow object to cool first - Always close -balance case door before taking the weight of Object . Air current causes balance to be unsteady . Never place chemicals directly on the pan , but weigh them in a Nessel ( weighing bottle dish boat small beaker ) it • Bunsen burner • hot plate • electronic oven • microwave • furnace ii 1 A warm object sets up convection currents inside the balance enclosure , which will make an object appear tighter than it really is .