Answer :
Answer :
(i) The number of atoms present in 7 g of lithium are, [tex]6.07\times 10^{23}[/tex]
(ii) The number of atoms present in 7 g of lithium are, [tex]1.204\times 10^{24}[/tex]
(iii) The number of moles of [tex]F_2[/tex] is, 1 mole
The number of moles of [tex]CO_2[/tex] is, 0.5 mole
The number of moles of [tex]OH^-[/tex] is, 1 mole
Explanation :
Part (i) :
First we have to calculate the moles of lithium.
[tex]\text{Moles of }Li=\frac{\text{Mass of }Li}{\text{Molar mass of }Li}[/tex]
Molar mass of Li = 6.94 g/mole
[tex]\text{Moles of }Li=\frac{7g}{6.94g/mol}=1.008mole[/tex]
Now we have to calculate the number of atoms present.
As, 1 mole of lithium contains [tex]6.022\times 10^{23}[/tex] number of atoms
So, 1.008 mole of lithium contains [tex]1.008\times 6.022\times 10^{23}=6.07\times 10^{23}[/tex] number of atoms
Thus, the number of atoms present in 7 g of lithium are, [tex]6.07\times 10^{23}[/tex]
Part (ii) :
First we have to calculate the moles of carbon.
[tex]\text{Moles of }C=\frac{\text{Mass of }C}{\text{Molar mass of }C}[/tex]
Molar mass of C = 12 g/mole
[tex]\text{Moles of }C=\frac{24g}{12g/mol}=2mole[/tex]
Now we have to calculate the number of atoms present.
As, 1 mole of carbon contains [tex]6.022\times 10^{23}[/tex] number of atoms
So, 2 mole of carbon contains [tex]2\times 6.022\times 10^{23}=1.204\times 10^{24}[/tex] number of atoms
Thus, the number of atoms present in 7 g of lithium are, [tex]1.204\times 10^{24}[/tex]
Part (iii) :
To calculate the moles of [tex]F_2[/tex] :
[tex]\text{Moles of }F_2=\frac{\text{Mass of }F_2}{\text{Molar mass of }F_2}[/tex]
Molar mass of [tex]F_2[/tex] = 38 g/mole
[tex]\text{Moles of }F_2=\frac{19g}{19g/mol}=1mole[/tex]
Thus, the number of moles of [tex]F_2[/tex] is, 1 mole
To calculate the moles of [tex]CO_2[/tex] :
[tex]\text{Moles of }CO_2=\frac{\text{Mass of }CO_2}{\text{Molar mass of }CO_2}[/tex]
Molar mass of [tex]CO_2[/tex] = 44 g/mole
[tex]\text{Moles of }CO_2=\frac{22g}{44g/mol}=0.5mole[/tex]
Thus, the number of moles of [tex]CO_2[/tex] is, 0.5 mole
To calculate the moles of [tex]OH^-[/tex] ions :
[tex]\text{Moles of }OH^-=\frac{\text{Mass of }OH^-}{\text{Molar mass of }OH^-}[/tex]
Molar mass of [tex]OH^-[/tex] = 17 g/mole
[tex]\text{Moles of }OH^-=\frac{17g}{17g/mol}=1mole[/tex]
Thus, the number of moles of [tex]OH^-[/tex] is, 1 mole
1. The number of atoms in 7 g of Li is 6.02×10²³ atoms
2. The number of atoms in 24 g of carbon is 1.204×10²⁴ atoms
3. The number of mole in 19 g of fluorine is 1 mole
4. The number of mole in 22 g of carbon dioxide is 0.5 mole
5. The number of mole in 17 g of Hydroxide ion is 1 mole
1. Determination of the number of atoms in 7 g of lithium
From Avogadro's hypothesis,
1 mole of Li = 6.02×10²³ atoms
But,
1 mole of Li = 7 g
Thus,
7 g of Li = 6.02×10²³ atoms
2. Determination of the number of atoms in 24 g of carbon
From Avogadro's hypothesis,
1 mole of C = 6.02×10²³ atoms
But,
1 mole of C = 12 g
Thus, we can say that
12 g of C = 6.02×10²³ atoms
Therefore,
24 g of C = (24 × 6.02×10²³) / 12
24 g of C = 1.204×10²⁴ atoms
3. Determination of the number of mole in 19 g of fluorine
- Mass = 19 g
- Molar mass of fluorine = 19 g/mol
- Mole =?
Mole = mass / molar mass
Mole of fluorine = 19 / 19
Mole of fluorine = 1 mole
4. Determination of the number of mole in 22 g of carbon dioxide, CO₂
- Mass = 22 g
- Molar mass of CO₂ = 12 + (2×16) = 44 g/mol
- Mole =?
Mole = mass / molar mass
Mole of CO₂ = 22 / 44
Mole of CO₂ = 0.5 mole
5. Determination of the number of mole in 17 g of Hydroxide ion, OH¯
- Mass = 17 g
- Molar mass of OH¯ = 16 + 1 = 17 g/mol
- Mole =?
Mole = mass / molar mass
Mole of OH¯ = 17 / 17
Mole of OH¯ = 1 mole
Learn more about Avogadro's number:
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Learn more about mole:
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