Empirical And Molecular Formula

Question 1

EF

Answer 1

The empirical or simplest formula (EF) of a compound shows smallest the whole-number ratio of the elements in that compound.

Question 2

MF

Answer 2

The molecular formula (MF) of a compound, on the other hand, shows the actual numbers of atoms of each element in that compound.

Question 3

steps

Answer 3

1) state the sample size. ex, if the percentage is given, choose a sample size of 100 g so that the percents = numbers
2) Since EF shows the whole number mole ratio of the elements, we must calculate the number of moles of each element.
3) Determine the mole ratio by dividing the larger by the smaller.
* Note that if the mole ratios of the elements are not close to whole numbers, they should not be rounded, rather they should be multiplied by the smallest common factor to obtain whole numbers

Question 4

molecular formula from empirical formula

Answer 4

molecular formula = X(empirical formula)

X = Molar mass of the compound / Mm of the empirical formula

Question 5

combustion analyzer

Answer 5

This is a device. The hydrogen in the compound will combine with the supplied oxygen to produce H2O and the carbon in the compound combines with oxygen to produce CO2. Then the amounts of H2O and CO2 produced are determined by measuring the mass increase in the H2O and CO2 absorbers. From the masses of H2O and CO2, we can determine their number of moles, and in turn, the number of moles of H and C, and by calculating the mole ratio, we find the EF.

Question 6

hydrates

Answer 6

must be ionic compound. water is present in compound but very loosely attached. heating it causes water to evaporate.

Question 7

hydrocarbon derivative

Answer 7

hydrogen is swapped out for another element in a “hydrocarbon”

Question 8

combustion analysis

Answer 8

allows you to take carbon and hydrogen or a derivative to find out HOW MUCH you have of each different part