The empirical formula of the nitrogen oxide that acts as a vasodilator and lowers human blood pressure is
. Empirical formula is the smallest whole number ratios of elements in a compound.
FURTHER EXPLANATION
To get the empirical formula from mass percent data, the following steps are followed:
1. Get the mass percent data for all the elements that make up the compound.
2. Assume that there is 100 grams of sample compound. Determine the equivalent masses of each element using the mass percent given.
3. Convert the mass of each element to number of moles.
4. Divide each calculated mole by the smallest mole value.
5. The quotient will be the subscript of the element in the compound. If a decimal is obtained, round off the answers to the nearest whole number. Some exceptions to this are the following decimals: x.25, x.33, x.50, and x.75. When these decimals are obtained, all the subscripts are multiplied by a number that will result in a whole number.
Applying the steps to the problem,
STEP 1: Get the mass percent.
Mass % of N = 53.85
Mass % of O = (100 - 53.85) = 46.15
STEP 2: Assume that 100 g sample is used and convert the mass % to mass in grams.
mass of N = 53.85% x 100 g = 53.85 g
mass of O= 46.15% x 100 g = 46.15 g
STEP 3: Convert mass to moles by dividing the given mass by the formula mass.

The moles may be written as the temporary subscripts of the elements in the compound as follows:

STEP 4: Divide the moles by the smallest mole value.

<u>STEP 5:</u> Multiply the subscripts by a number that would give the smallest whole number ratio.
Since the decimal is 1.33 it cannot be rounded off to 1. It should be multiplied by 3 to get the smallest whole number.
NOTE: All subscripts must be multiplied by the same factor, 3.

To check if the empirical formula is correct, calculate the mass % of each element based on the formula and compare with the given in the problem.


Since the values are the same from the given, the answer is correct.
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Keywords: empirical formula, compounds