1. You wish to purify a compound with a boiling point of 235°C by simple distillation. In order to avoid unwanted decomposition that can occur at such high temperatures, you wish to perform your distillation at a lower temperature. How can you change the conditions of the distillation you will perform to efficiently accomplish this goal?
2. Explain how your change will produce the desired effect?

Explanation:

To purify a substance whose boiling point is so  high that on reaching boiling point , the substance may undergo chemical change , we manage boiling of substance at relatively lower temperature . This can be done at reduced pressure . Boiling point is dependent on the external pressure. If external pressure is reduced , boiling can be managed at a temperature far below actual  boiling point . In this way we can manage the substance to boil at lower temperature thus we can save the substance to undergo chemical change.

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation: