First we must write a balanced chemical equation for this reaction
The mole ratio for the reaction between 
and 
is 1:2. This means 1 moles of will neutralize 2 moles . Now we find the moles of each reactant based on the mass and molar mass.
The was enough to neutralize the acid because 18.87:39.67 is the same as 1:2 mol ratio.
The balanced reaction is as below
3A₂B + 2DC₃→ 6 AC + D₂B₃
The number that must be to the left of AC is 6
Explanation
- According to the law of mass conservation , the number of atoms in reactant side must be equal to number to the number of atoms in product side.
- Therefore the equation above is balance since it obey the law of mass conservation.
- For example there is 6 atoms of A in reactant side and 6 in product side.
As per the given chemical formula- Na2CO3.10H2O, one mole of the chemical compound contains 13 moles of oxygen atoms. Hence
Number of moles of oxygen atoms in one mole of Na2CO3.10H2O = 13
number of moles of oxygen atoms in 0.2 moles of Na2CO3.10H2O = 13 X 0.2 = 2.6
Now, one mole of a substance contains 6.022 X 10^23 particles of the substance. Thus
number of atoms of oxygen in one mole of oxygen atom = 6.022 X 10^23
number of moles of oxygen atoms in 2.6 moles of oxygen atoms = 2.6 X 6.022 X 10^23 = 15.657 X 10^23
= 1.566 X 10^24
Thus, there are 1.566 X 10^24 atoms of oxygen in 0.2 moles of Na2CO3.10H2O.
4.7
<span>the atomic mass of nitrogen is 14. There is 1 nitrogen atom in the molecule so the percentage of N is :
14/35 x100% = 40%</span>
