How many grams of sucrose must be added to 552 grams of water to give a solution?

1.35x10^-5 grams of sucrose must be added to produce a solution with vapor pressure of 15.5 mmHg.
Solution:
We can use the Raoult's law to get the mole fraction of water Xsolvent present in the solution:
     Psolution = Xsolvent Posolvent
     (17.5 mmHg - 2.0 mmHg) = Xsolvent (17.5 mmHg)
     Xsolvent = 0.886 

We use the molar mass of water to compute for its number of moles:
     moles of solvent = (552 g H2O)(1 mol H2O / 18.015 g H2O)
                                = 30.64 mol H2O

From the mole fraction of the water given by
     Xsolvent = moles of solvent / sum of moles of solution
                    = moles of H2O/ (moles of sucrose + moles of H2O)
     0.886 = (30.64 mol) / (moles of sucrose + 30.64 mol) 

we can solve for the number of moles of sucrose:
     moles of solute = (30.64 mol / 0.886) - 30.64 mol = 3.94 mol sucrose

We can now calculate for the mass of sucrose using its molar mass:
     mass of sucrose = (3.94 mol sucrose)(342.3 g sucrose / 1 mol sucrose)
                                = 1.35x10^-5 grams

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

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