Question

In \[6.72\,g\] of\[{N_2}{H_4}\], how many?
A.How many \[{N_2}{H_4}\] molecules are present?
B.How many \[N\] atoms are present?
C.How many protons are present?

Answer 1

Hint:Hydrazine is an inorganic compound having the chemical formula of \[{N_2}{H_4}\]. A mole is defined as \[6.02214076 \times {10^{23}}\] of a chemical unit in the terms of ions, atoms, molecules, etc.
\[1\,mole\, = \,6.022\, \times \,{10^{23}}\,atoms\]
Therefore, for \[1\] atom will be;
\[1\,atom\, = \,\dfrac{1}{{6.022\, \times \,{{10}^{23}}}}\,moles\]
So, the answer will be;
\[1\,atom\, = 1.66\, \times \,{10^{ - 24}}\,moles\]

Complete step-by-step answer: First, we need to find how many \[{N_2}{H_4}\] molecules are present?
Let’s observe the given values;
Here, we have \[{N_2}{H_4}\]\[ = \,6.72\,g\]
To calculate the number of moles;
Let’s use the equation;
Number of moles, \[n\, = \,\dfrac{{mass}}{{molecular\,mass}}\]
The given mass of hydrazine \[({N_2}{H_4})\, = \,6.72\,g\]
The molecular mass of hydrazine \[({N_2}{H_4})\,\];
\[ = \,14\, \times \,2\, + \,1\, \times \,4\]
 \[ = \,32{\text{ }}g/mol\]
Substitute the values in above equation,
\[n\, = \,\dfrac{{6.72\,g}}{{32\,g/mol}}\]

So, the number of moles will be;
\[n\, = \,0.21\,moles\]
We have to multiply with the Avogadro’s number to get the \[({N_2}{H_4})\,\] molecules.
Now, let’s calculate the number of molecules present in \[6.72\,g\] of \[({N_2}{H_4})\,\]
\[ = \,0.21\, \times \,6.023\, \times \,{10^{23}}\]
\[ = \,1.2648\, \times \,{10^{23}}\] molecules
So, the answer obtained will be, \[1.2648\, \times \,{10^{23}}\] molecules are present in \[6.72\,g\] of \[({N_2}{H_4})\,\] .
Secondly, we need to find that how many \[N\] atoms are present;
So, for that we must know that there are two atoms of nitrogen participating for every molecule of hydrazine;
\[ = \,1.2648\, \times \,{10^{23}}\, \times \,2\]
\[ = \,2.52\, \times \,{10^{23}}\] atoms of nitrogen.
Thirdly, we need to find how many protons are present;
We know that the atomic number will be equal to the number of electrons and the electrons are equal to the number of protons. So, we have \[7\] protons of nitrogen because the nitrogen’s atomic number is \[7\] and \[1\] protons of hydrogen because the atomic number is \[1\] .
But we need to calculate the atoms of hydrogen so that the calculation can be easy;
So, for that we must know that there are four atoms of hydrogen participating for every molecule of hydrazine;
\[ = \,1.2648\, \times \,{10^{23}}\, \times \,4\]
\[ = \,5.05\, \times \,{10^{23}}\] atoms of hydrogen.
Now, let’s calculate the number of protons;
So, the total number of protons will be;
\[ = \,7\, \times \,2.52\, \times \,{10^{23}}\, + \,1\, \times \,5.05\, \times \,{10^{23}}\]
\[ = \,22.69\, \times \,{10^{23}}\] protons are present.

Note:A mole is a unit measurement for the amount of substance in the international system of units i.e., SI unit. A mole of a particle or a mole of a substance is defined as \[6.02214076 \times {10^{23}}\] of a chemical unit, that can be ions, atoms, molecules, etc. Originally it was defined as the number of atoms in \[12{\text{ }}g\] of carbon-12.