Atechnician tares a 100.0 ml volumetric flask at 150.00 g. after adding sodium chloride to the flask it then weighs 158.84 g. assuming an error of 0.2 ml in the volumetric volume and 0.005 g in the weight, calculate the molar concentration of sodium chloride and its associated standard deviation.

Explanation:

Since, it is known that number of moles equal to the mass divided by the molar mass of a substance.

As molar mass of NaCl is 58.44 g/mol. Hence, number of moles of NaCl present in 158.84 g are calculated as follows.

          No. of moles =

                                =

                                 = 2.715 mol

Therefore, there are 2.715 moles present in 100 ml solvent.

Hence, the molar concentration will be as follows.

       Molar concentration = mol/liter

                                        = 27.15 M

It is given that error in weight is 0.005 g and error in volume is 0.2 ml.

Hence, total volume will be (100ml + 0.2 ml) = 100.2 ml.

Therefore, now molar concentration will be as follows.

             Molar concentration = mol/liter      

                                              = 27.09 M

Thus, calculate the deviation as follows.

                        (27.15 - 27.09) mol/liter

                       = 0.06 mol/liter

Hence, we can conclude that the molar concentration of sodium chloride 27.15 M and its associated standard deviation is 0.06 mol/liter.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.

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