Water Hardness experiment! Please help me with these follow up questions! If you

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Water Hardness experiment! Please help me with these follow up questions! If you need more information please let me know, thank you!

Here are my calculated results from my experiment!

Avg Volume of EDTA used = 2.3 mL

mL of water sample used = 10 mL

Concentration of Ca2+ ions per liter of water (mol/L) = 0.0023 M

Water Hardness ppm CaCO3 = 230 ppm CaCO3

Classification of Water = Very Hard

1) Approximately how much calcium would you ingest by drinking six, 8-oz glasses of your local water? Hint: 1 oz (fluid ounce) = 29.57 mL

2) The endpoint was overshot! This caused the solution to turn instantly blue. How will this error affect the reported hardness of the water, too high or too low? Explain.

3) In this experiment an EDTA titration was performed. Another common type of titration is an acid-base titration. Specifically, a neutralization titration can be used to determine the concentration of a strong acid if it is titrated with a strong base whose concentration is known. This method uses stoichiometry to determine the unknown acid’s concentration.

Let’s say a student had 1.0 M sodium hydroxide (NaOH) and found a solution of sulfuric acid (H2SO4) whose label had faded. She took 10.0 mL of the H2SO4, added phenolphthalein as an indicator, and titrated the solution. It took 25.8 mL of the NaOH to complete the titration. What was the concentration of the H2SO4? The neutralization reaction is below:

H2SO4 (aq) + 2 NaOH (aq) --> 2 H2O (l) + Na2SO4 (aq)

Explanation / Answer

H2SO4(aq) + 2NaOH(aq) ----> 2H2O(l) + Na2SO4(aq)

Moles of NaOH used in neutralisation = (1/2)*moles of H2SO4 used

or, 1*0.0258 = (1/2)*Molarity of H2SO4 solution*0.01

or, Molarity of H2SO4 solution = 5.16 M

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