You are given an unknown gaseous binary compound (that is, a compound consisting of two different elements). When 10.0 g of the compound is burned in excess oxygen, 16.3 g of water is produced. The compound has a density 1.38 times that of oxygen gas at the same conditions of temperature and pressure. Give a possible identity for the unknown compound.

Interpretation: The possible identity of diatomic compound having a density of 1.38 times of O2 at same temperature and pressure should be identified, if the 10 g of compound is producing 16.3 g of H2O while burning in oxygen.

Concept introduction:

• Equation for number of moles are,

Number of moles   =   MassMolar mass

• According to ideal gas equation for molar mass in terms of density is,

Molar mass  =   Density  ×  R  ×  Temperature    pressure

• Mass of a substance from its number of moles is,

Number of moles  ×  Molecular mass in grams  =  taken Mass

• Mole ratios between the reactant and products of a reaction are depends upon the coefficients of respective reactant in a balanced chemical equation.

Explanation

To find: the molar mass of given unknown diatomic compound.

The molar mass of given unknown diatomic compound is 44.2 g .

The density of unknown diatomic compound is 1.38 times of density of O2.

According to ideal gas equation for molar mass in terms of density is,

Molar mass  =   Density  ×  R  ×  Temperature    pressure

At constant temperature and pressure,

molar mass ∝ density

Therefore,

molar mass of given compoundmolar mass of O2  ∝  density of given compounddensity of O2

The molar mass of O2 is 32 g.

Then, the molar mass of given compound is,

molar mass of given compound  =  1.38 × molar mass of O2  =  1.38 × 32 = 44.2

Hence,

The molar mass of given unknown diatomic compound is 44.2 g.

To find: the number of moles of unknown diatomic compound and produced 16.3 g of H2O in the given reaction.

The number of moles of unknown diatomic compound is 0.4443 mol.

The number of moles of produced H2O is 0.4443 mol.

Let’s take the formula for unknown diatomic compound is AxHy(since the compound should have a H-element because it is producing H2O while burning in O2).

The mass of AxHy is given as 10 g.

The molar mass of given AxHy is 44.2 g

The mass of H2O is given as 16.3 g.

The molar mass of O2 is 32 g.

Equation for number of moles is,

Number of moles   =   MassMolar mass

Therefore,

The number of moles of AxHy is,

Number of moles   =   10 g44.2 g/mol  = 0