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Question: In \[6.72\,g\] of\[{N_2}{H_4}\], how many? A.How many \[{N_2}{H_4}\] molecules are present? B.Ho...

In 6.72g6.72\,g ofN2H4{N_2}{H_4}, how many?
A.How many N2H4{N_2}{H_4} molecules are present?
B.How many NN atoms are present?
C.How many protons are present?

Explanation

Solution

Hydrazine is an inorganic compound having the chemical formula of N2H4{N_2}{H_4}. A mole is defined as 6.02214076×10236.02214076 \times {10^{23}} of a chemical unit in the terms of ions, atoms, molecules, etc.
1mole=6.022×1023atoms1\,mole\, = \,6.022\, \times \,{10^{23}}\,atoms
Therefore, for 11 atom will be;
1atom=16.022×1023moles1\,atom\, = \,\dfrac{1}{{6.022\, \times \,{{10}^{23}}}}\,moles
So, the answer will be;
1atom=1.66×1024moles1\,atom\, = 1.66\, \times \,{10^{ - 24}}\,moles

Complete step-by-step answer: First, we need to find how many N2H4{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=massmolecularmassn\, = \,\dfrac{{mass}}{{molecular\,mass}}
The given mass of hydrazine (N2H4)=6.72g({N_2}{H_4})\, = \,6.72\,g
The molecular mass of hydrazine (N2H4)({N_2}{H_4})\,;
=14×2+1×4= \,14\, \times \,2\, + \,1\, \times \,4
=32 g/mol= \,32{\text{ }}g/mol
Substitute the values in above equation,
n=6.72g32g/moln\, = \,\dfrac{{6.72\,g}}{{32\,g/mol}}

So, the number of moles will be;
n=0.21molesn\, = \,0.21\,moles
We have to multiply with the Avogadro’s number to get the (N2H4)({N_2}{H_4})\, molecules.
Now, let’s calculate the number of molecules present in 6.72g6.72\,g of (N2H4)({N_2}{H_4})\,
=0.21×6.023×1023= \,0.21\, \times \,6.023\, \times \,{10^{23}}
=1.2648×1023= \,1.2648\, \times \,{10^{23}} molecules
So, the answer obtained will be, 1.2648×10231.2648\, \times \,{10^{23}} molecules are present in 6.72g6.72\,g of (N2H4)({N_2}{H_4})\, .
Secondly, we need to find that how many NN atoms are present;
So, for that we must know that there are two atoms of nitrogen participating for every molecule of hydrazine;
=1.2648×1023×2= \,1.2648\, \times \,{10^{23}}\, \times \,2
=2.52×1023= \,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 77 protons of nitrogen because the nitrogen’s atomic number is 77 and 11 protons of hydrogen because the atomic number is 11 .
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;
=1.2648×1023×4= \,1.2648\, \times \,{10^{23}}\, \times \,4
=5.05×1023= \,5.05\, \times \,{10^{23}} atoms of hydrogen.
Now, let’s calculate the number of protons;
So, the total number of protons will be;
=7×2.52×1023+1×5.05×1023= \,7\, \times \,2.52\, \times \,{10^{23}}\, + \,1\, \times \,5.05\, \times \,{10^{23}}
=22.69×1023= \,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 6.02214076×10236.02214076 \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 g12{\text{ }}g of carbon-12.