Question

1)How many moles of N are in 0.237 g of N2O?

2)What is the average mass of a single phosphorus atom in grams?

3)A compound is 54.53% C, 9.15% H, and 36.32% O by mass. What is its empirical formula?

4)The molecular mass of the compound is 132 amu. What is the molecular formula?

Answer 1

1)

Mass of   is

Molar mass of is

There are 2 moles of Nitrogen () in every mole of

Number of moles of is

Number of moles of in the given amount of is

2)

One mole of phosphrous weighs - 30.974 g

one mole is = 6.023x 10²³ atoms

Average mass of single phosphrous atom is

3)

Molar mass of Hydrogen ()

Molar mass of Carbon ()

Molar mass of Oxygen ()

Let the empirical formula be

Let the molar mass of substance be

percentages of elements by mass are

For Carbon    ----------- (1)

For Hydrogen    ---------- (2)

For Oxygen ---------- (3)

Dividing the equations (1) and (2)    that is

Dividing the equations (2) and (3)    that is

Hence empirical formula is

4)

Molecular mass of compound is

Hence

and Molecular formula is