How do you calculate empirical formula of a compound?

Answer 1

If a question gives you a compound showing percentages , you have to find the simplest ratio of atoms in the compound.

For instance, one question asks you to determine the empirical formula that has 89% oxygen and 11% hydrogen.

Assume, for the purposes of this step, that the masses of all these substances total 100 grams, of which 89 grams are oxygen and 11 grams of hydrogen.

Second step, use #n = m-: M# to calculate the number of moles. It is assumed that n = number of moles, m = mass of substance, and M = molar mass (equivalent to atomic weight on the periodic table).

number of moles of hydrogen = 11 grams #-:#1 g/mol = 11 moles number of moles for oxygen = 89 grams #-:#16 g/mol = 5.56 moles

Divide the total number of moles by the smallest in the third step.

Hydrogen (H): 11 #-:#5.56 = 2.00 Oxygen (O): 5.56 #-:#5.56 = 1.00 *round it off to nearest whole number, then assign it as subscripts.

Therefore the empirical formula is #H_2O#.

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Answer 2

Serenity Allen

A compound's empirical formula is found by dividing each mole value by the smallest number of moles that can be obtained, rounding the resultant values to the nearest whole number, and then computing the ratio of atoms present in the compound. This process is usually carried out by calculating the mass percentages of each element in the compound and converting them into moles.

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Answer 3

Cameron Andrews

To calculate the empirical formula of a compound:

Determine the mass of each element present in the compound.
Convert the masses of each element to moles.
Determine the mole ratio of each element by dividing the moles of each element by the smallest number of moles calculated.
If necessary, round the mole ratios to the nearest whole number to obtain the simplest whole number ratio.
Write the empirical formula using the whole number ratios of the elements.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.