Determine the number of grams in Na present in 4.0g of NaOH.

The answer to your question is 2.3 g

Explanation:

Data

Molecule = NaOH

grams of Na in 4 g of NaOH

Process

1.- Calculate the molecular mass of NaOH

molecular mass = (1 x 23) + (1 x 16) + (1 x 1)

                          = 23 + 16 + 1

                          = 40 g

2.- Calculate the atomic mass of sodium

atomic mass = 23 g

3.- Use proportions to solve this problem

                     40 g of NaOH  4 g of NaOH

                      23 g of Na        x

                      x = (4 x 23) / 40

                     x = 2.3 g

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

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