Question

How would you calculate the number of grams of sodium oxide, \[N{{a}_{2}}O\], that will be produced when 5.00 moles react with oxygen given in the reaction:
\[4Na+{{O}_{2}}\to 2N{{a}_{2}}O\]

Answer 1

Hint: The moles are defined as the convenient unit for measuring the large number of molecules and atoms present in the compound. The 1 mole of the substance is equal to the Avogadro number. And the Avogadro number is equal to \[6.023\times {{10}^{23}}\]elementary entities. These elementary entities can be the atoms, molecules or ions.

Complete step-by-step answer:The molar mass of the substance can be calculated by adding the atomic masses of all those atoms which are present in the compound. Here in sodium oxide we have three atoms and they are two atoms of sodium and one atom of oxygen. the atomic mass of sodium is 23\[gmo{{l}^{-1}}\]and oxygen is 16\[gmo{{l}^{-1}}\]. So the molar mass of sodium oxide will be :
\[N{{a}_{2}}O\](molar mass)= 23+23+16= 62\[gmo{{l}^{-1}}\]
So now on observing the equation we get to know that,
2 moles of sodium oxide is produced by reacting =1 mole of oxygen
5 moles of sodium oxide is produced by reacting= \[\dfrac{5}{2}=2.5\]moles of oxygen
Now we will convert the moles into the grams by the following formula:
\[number of moles=\dfrac{given mass}{molar mass}\]
Number of moles = 2.5
Molar mass = 62\[gmo{{l}^{-1}}\]
Now substituting the values in formula we get,
\[2.5=\dfrac{given mass}{62}\]
On simplifying we get
Given mass= 155g
So the answer is 155g.

Note:If the question had been asked to tell the number of atoms of sodium oxide then we would have multiplied the moles by the Avogadro number. If they would have asked to calculate the answer in volume then we would have multiplied the number of moles by 22.4 L. if the question would be to tell the number of molecules then also we would have multiplied the number of moles by the Avogadro number.