Chemical calculations

10 important questions on Chemical calculations

what do chemical calculations not take into account?

the mass if each atom

What is the relative atomic mass (Ar)

The average mass of naturally occurring atoms of an element on a scale

What is the relative molecular mass (Mr)

The sum of the relative atomic masses in the formula
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Why do you need the stoichiometry of a formula

You need the stoichiometry to know the ratio in which the reactants combine, if you know that you can calculate what mass of one reactant we need to add to each other so they react exactly

How do you calculate the percentage by mass

Mass of a particular element in one mole of a compound divided by mass of one mole of a compound

How do you calculate the volume of gas

Number of moles divided times 24

How do you calculate the percentage yield

Actual yield divided by predicted yield

How do you calculate the percentage purity

Mass of pure product divided by mass of impure product

How do you find the empirical formula

First you note the mass of each element in the formula. Then you divide by the relative atomic masses. After that you divide the moles by the lowest number of moles. You now know the stoichiometry and can write down the formula

How do you find the molecular formula

First off you find the empirical formula mass. After that you divide the relative formula mass with the empirical formula mass. You then multiply the answer from step two with the formula

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