Burning a compound of calcium, carbon and nitrogen in oxygen generates calcium oxide (CaO), carbon dioxide (CO2) and nitrogen dioxide (NO2). A small sample gives 3.106 g CaO, 2.439 g CO2, and 5.097g NO2. Determine the empirical formula of the compound.

CaCN₂

Explanation:

A compound of calcium, carbon and nitrogen CaₐCₓNₙ in oxygen will burning producing:

CaₐCₓNₙ + O₂ → aCaO + xCO₂ + nNO₂

Moles of the oxides CaO, CO₂, NO₂ are:

CaO: 3.106g ₓ (1 mole / 56.08g) = 0.0554 moles of CaO = moles of Ca

CO₂: 2.439g ₓ (1mole / 44g) = 0.0554 moles CO₂ = moles C

NO₂: 5.097g ₓ (1mole / 46g) = 0.111 moles NO₂ = moles N

Empirical formula is the chemical formula that represents the simplest ratio of elements in a compound.

Having as basis 0.0554 moles (The lower number of moles):

0.0554 moles Ca / 0.0554 = 1 Ca

0.0554 moles C / 0.0554 = 1 C

0.111 moles N / 0.0554 = 2N

Thus, the compound CaₐCₓNₙ  has as empirical formula:

Ca₁C₁N₂ = CaCN₂

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2