The percent composition by mass of certain compound is 35.5 percent carbon, 4.8 percent hydrogen, 37.9 percent oxygen, 8.3 percent nitrogen, and 13.5 percent sodium. what is the molecular formula if the molar mass is roughly 170 grams per mole

Answer : The molecular formula of a compound is,

Solution :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 35.5 g

Mass of H = 4.8 g

Mass of O = 37.9 g

Mass of N = 8.3 g

Mass of Na = 13.5 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of O = 16 g/mole

Molar mass of N = 14 g/mole

Molar mass of Na = 23 g/mole

Step 1 : convert given masses into moles.

Moles of C =

Moles of H =

Moles of O =

Moles of N =

Moles of Na =

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =

For H =

For O =

For N =

For Na =

The ratio of C : H : O : N : Na = 5 : 8 : 4 : 1 : 1

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula =

The empirical formula weight = 5(12) + 8(1) + 4(16) + 1(14) + 1(23) = 169 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

Molecular formula =

Therefore, the molecular of the compound is,

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.

i do not get it   at all