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O = \(\frac \) ? Mass = \(\frac \) ? Molecule wt

Empirical formula The empirical formula of a compound may be defined as the formula which gives the simplest whole number ratio of atoms of the various elements present in the molecule of the compound. _sixH_{a dozen}O₆), is CH₂O which shows that C, H, and O are present in the simplest ratio of 1 : 2 : 1. Rules for writing the empirical formula The empirical formula is determined by the following steps :

1. Split the new part of per elements by the atomic bulk. This provides the new relative amount of moles of various issue introduce regarding compound.
2. Divide the brand new quotients gotten on significantly more than action from the littlest of them to get an easy proportion away from moles of several factors.
3. Proliferate new rates, very acquired from the the ideal integer, if required, so you’re able to receive entire number proportion.
4. Ultimately write down the newest icons of the numerous aspects side of the front side and place the above amounts as the subscripts into straight down right hand spot of any icon. This may depict the empirical formula of the material.

Example: A compound, to your study, gave the following constitution : Na = cuatrostep three.4%, C = 11.3%, O = forty-five.3%. Calculate their empirical formula [Nuclear masses = Na = 23, C = 12, O = 16] Solution:

O₃

_{Determination molecular formula : Molecular formula = Empirical formula ? n n = \(\frac \) Example 1: What is the simplest formula of the compound which has the following percentage composition : Carbon 80%, Hydrogen 20%, If the molecular mass is 30, calculate its molecular formula. Solution: Calculation of empirical formula :}

_{? Empirical formula is CH3. Calculation of molecular formula : Empirical formula mass = 12 ? 1 + 1 ? 3 = 15 n = \(\frac =\frac \) = 2 Molecular formula = Empirical formula ? 2 = CH3 ? 2 = C2H6.}

Example 2: On heating a sample of CaC, volume of CO₂ evolved at NTP is 112 cc. Calculate (i) Weight of CO₂ produced (ii) Weight of CaC taken (iii) Weight of CaO remaining Solution: (i) Mole of CO₂ produced \(\frac =\frac \) mole mass of CO₂ = \(\frac \times 44\) = 0.22 gm (ii) CaC > CaO + CO₂(1/200 mole) mole of CaC = \(\frac \) mole ? mass of CaC = \(\frac \times 100\) = 0.5 gm (iii) mole of CaO produced = \(\frac \) mole mass of CaO = \(\frac \times 56\) = 0.28 gm * Interesting by we can apply Conversation of mass or wt. of CaO = wt. of CaC taken – wt. of CO₂ produced = 0.5 – 0.22 = 0.28 gm

Example 3: If all iron present in 1.6 gm Fe₂ is converted in form of FeSO₄. (NH₄)₂SO₄.6H₂O after series of reaction. Calculate mass of product obtained. Solution: If all iron will be converted then no. of mole atoms of Fe in reactant product will be same. ? Mole of Fe₂ = \(\frac =\frac \) mole atoms of Fe = 2 ? \(\frac =\frac \) mole of FeSO₄. (NH₄)₂SO₄.6H₂O will be same as mole atoms of Fe because one atom of Fe is present in one molecule. ? Mole of FeSO₄.(NH₄)₂.SO₄.6H₂ = \(\frac \times 342\) = 7.84 gm.