The student is to go to the workshop site, open a new workbench (Fileselect New WorkBench (Cntl-N). Then select...
The student is to go to the workshop site, open a new workbench (Fileselect New WorkBench (Cntl-N). Then select ToolsGlasswareBeakers600 ml Beaker.
After the Beaker appears, using the LEFT mouse button drag the beaker to the center of the work bench, then RIGHT click and Select "Set as Recipient״.
Select from the WStockroom Explorer (left hand side of screen) Distilled Water, and using the Left Mouse button, DRAG the water container onto the Workshop bench. Right click on the distilled water container and then select "set as Source״. Notice that the water container moves over your beaker.
At the bottom of the workbench screen, look for the box next to "TRANSFER AMOUNT mL״. Type in 100, and then click the POUR button. Observe that 100 mL of water has been added to your beaker.
Note down the Solution Info on the right hand side of the workbench. The pH is neutral (as demonstrated by equal concentrations of -OH and +H ions).
Nov 24, 2006
Nov 24, 2006
In this Pre-lab you will design and conduct the following acid base titration:1) Hydrochloric acid, HCl (strong acid), with...
In this Pre-lab you will design and conduct the following acid base titration:1) Hydrochloric acid, HCl (strong acid), with sodium hydroxide, NaOH (strong base)2) Hydrochloric acid, HCl (strong acid), with ammonia, NH3 (weak base)3) Acetic acid, HC2H3O2 (weak acid), with sodium hydroxide, NaOH (strong base)4) Acetic acid, HC2H3O2 (weak acid), with ammonia, NH3 (weak base)Students design their own experiments to complete the titration experiments. They a formal laboratory report addressing the following questions.In which trial(s) did Phenolphthalein change color at about the same time as the large increase in pH occurred at the equivalence point? In which trial(s) was there a significant difference in these two times? Suggest and test a more suitable indicator for the designed experiments. The stock room of the virtual lab features other indicators such as Bromocresol Green, Cresol Red, Methyl Orange and Methyl Red. By examining a titration curve, how can you decide which acid-base indicator to use to find the equivalence point?Of the four titration curves, which combination of strong or weak acids and bases had the longest vertical region of the equivalence point? The shortest? The acid-base reaction between HCl and NaOH produces a solution with a pH of 7 at the equivalence point (NaCl + H2O). Why does an acid-base indicator that changes color at pH 5 or 9 work just as well for this reaction as one that changes color at pH 7? In general, how does the shape of a curve with a weak specie (NH3 or HC2H3O2) differ from the shape of a curve with a strong specie (NaOH or HCl)? Write each of the equations for the acid/base titrations. Use a data acquisition program to record Vol NaOH vs. pH and plot the titration curves.
Mar 04, 2004
Feb 25, 2011