Questions 1. Calculate the molar mass of borax from the formula Na2B4O7.10H20. 2. What mass of borax is needed to prepar

[answerhappygod]

Questions 1 Calculate The Molar Mass Of Borax From The Formula Na2b4o7 10h20 2 What Mass Of Borax Is Needed To Prepar 1 (79.02 KiB) Viewed 78 times

Questions 1. Calculate the molar mass of borax from the formula Na2B4O7.10H20. 2. What mass of borax is needed to prepare a 0.050000 mol-dm borax solution with a volume of: a) 200.00 cm3; and b) 250.00 cm? Note that the volume of a standard flask is accurate to 2 decimal places. Report your answer to the correct number of significant figures. 3. When you calculate the mass of borax needed to make up the standard solution, do you include the "10 H20" in the formula for borax? Why/why not? 4. Suppose you failed to mix the borax solution properly. How would this error be reflected in the average titre? 5. What is the purpose of the trial titration? 6. Explain why the walls of the flask are washed with de-ionised water during the titration. How does this affect the outcome of the titration? 7. How does the equivalence point of a titration differ from its end point? 8. When NH3 is titrated with HCl the pH at the equivalence point of the titration is equal to 5. Which of the following indicators would be suitable for this titration? Explain your answer. Indicator pH range for change Colour change Methyl orange 3.1 -4.5 red yellow Methyl red 4.2-6.3 red yellow Bromothymol blue 6.0 - 7.6 yellow blue 9. Name two other possible sources of error in this experiment (apart from not mixing the borax solution properly as mentioned in question 4). Be specific, "random" or "systematic" error is not sufficient.