Question

How many atoms of oxygen are contained in 47.6g of $A{{l}_{2}}{{(C{{O}_{3}})}_{3}}$? The molar mass of $A{{l}_{2}}{{(C{{O}_{3}})}_{3}}$ is $233.99g\,mo{{l}^{-1}}$.

Answer 1

We need to know about the molecular weight of the molecules to solve this type of questions and then simply apply mole concepts to solve this type of questions.

Complete step-by-step answer: In order to answer the question, we need to know about moles and molar mass. Now, matter is made up of atoms, and as matter has mass, then the atoms should have an individual mass. Molar mass of an element or compound is the mass which houses $6\times {{10}^{23}}$ particles. For, example, the hydrogen molecule has a molar mass of 2 grams. This means 2 grams of hydrogen contains $6\times {{10}^{23}}$atoms, and this number is also called the Avogadro’s number.
Number of moles of an element or a compound is the ratio of its given mass taken by the user, to its molar mass. More is the number of moles, more is the concentration of the substance.
First we need to know how to calculate the molecular weight of water molecules. So first let's see how to find out the molecular weight of aluminium carbonate.
Molar mass of aluminium carbonate is 233.99g
So 233.99 gram is the weight of 1 mole
So 47.6 gram is the weight of 0.2 mole.
Now from the chemical formula of aluminium carbonate we can say that every mole of this salt contains
two moles of aluminium, $2\times Al$
three moles of carbon, $3\times C$
nine moles of oxygen, $3\times 3\times O$
So 0.2 mole of the sample contains 1.8 moles of oxygen.
Now 1 mole of oxygen contains $6\times {{10}^{23}}$ no of atoms
So 1.8 moles of oxygen contains $1.1\times {{10}^{24}}$ no of atoms

Note: Mole concept provides a selected measure of the amount of atoms or molecules during a bulk sample of matter. A mole is defined as a substance containing the identical number of discrete entities (atoms, molecules, ions, etc.)