There will also be a help session before the lab practical.Īt the end of the lab final you will wash all glassware used or any dirty glassware in your locker, wash your unknown vials and remove the labels, checkin your locker and return your key, and evaluate the lab. It would be a good idea to wash any glassware you might use the lab period before the lab practical. There is no talking during the practical such that students cannot help each other and the TA may only help you with equipment problems. You may only use a calculator and a pencil on the practical. You will have 1.5 hours to do the practical.
You must know how to weigh by difference (Preweigh, tare sample and small container to zero, transfer sample to flask, and place the small container back on balance to get mass) and titrate the sample using the buret in order to do well.īe sure to read the instructions for the practical toward the end the CHM151L lab manual and do the practice problem on the next page. The molecular formula of the compound will be provided during the final. The compound will be different than the compound used in experiment 6. The second part of the experiment is very similar to the last part of experiment 6 where samples of the unknown were weighed out, dissolved in water, and titrated with the dilute NaOH using phenolphthalein as the indicator to determine the percent by mass of a compound in the unknown. The molarity of the dilute NaOH will be calculated! A similar quantitative dilution was done in experiment 3 when you diluted 5.0 M HCl to 0.50M HCl using a volumetric flask and pipet. 1-How many grams of NaCl would be needed to prepare 150.00 L of a 1.402 M NaCl solution?Ģ- first a standardized solution of sodium hydroxide (NaOH) will be quantitatively diluted to about 0.1 M but not exactly 0.1M.