Respuesta :
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] .....(1)
According to mole concept:
1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of particles.
- For A: 2.12 g of potassium bromide
Given mass of KBr = 2.12 g
Molar mass of KBr = 119 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of KBr}=\frac{2.12g}{119g/mol}=0.0178mol[/tex]
1 mole of potassium bromide contains 1 mole of potassium element and 1 mole of bromide element.
So, 0.0178 moles of potassium bromide will contain [tex](1\times 0.0178\times 6.022\times 10^{23})=1.07\times 10^{22}[/tex] number of potassium atoms and
- For B: 0.1488 g of phosphoric acid
Given mass of phosphoric acid = 0.1488 g
Molar mass of phosphoric acid = 98 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of phosphoric acid}=\frac{0.1488g}{98g/mol}=0.00152mol[/tex]
1 mole of phosphoric acid contains 3 moles of hydrogen element, 1 mole of phosphorus element and 4 moles of oxygen element.
So, 0.00152 moles of phosphoric acid will contain [tex](3\times 0.00152\times 6.022\times 10^{23})=2.75\times 10^{21}[/tex] number of hydrogen atoms, [tex](1\times 0.00152\times 6.022\times 10^{23})=9.15\times 10^{20}[/tex] of phosphorus atoms and [tex](4\times 0.00152\times 6.022\times 10^{23})=3.66\times 10^{21}[/tex] number of oxygen atoms.
- For C: 23 kg of calcium carbonate
Given mass of calcium carbonate = 23 kg = 23000 g (Conversion factor: 1 kg = 1000 g)
Molar mass of calcium carbonate = 100 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of calcium carbonate}=\frac{23000g}{100g/mol}=230mol[/tex]
1 mole of calcium carbonate contains 1 mole of calcium element, 1 mole of carbon element and 3 moles of oxygen element.
So, 230 moles of calcium carbonate will contain [tex](1\times 230\times 6.022\times 10^{23})=1.38\times 10^{26}[/tex] number of calcium atoms,
- For D: 78.452 g of aluminium sulfate
Given mass of aluminium sulfate = 78.452 g
Molar mass of aluminium sulfate = 342.15 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of aluminium sulfate}=\frac{78.452g}{342.15g/mol}=0.229mol[/tex]
1 mole of aluminium sulfate contains 2 moles of aluminium element, 3 moles of sulfur element and 12 moles of oxygen element.
So, 0.229 moles of aluminium sulfate will contain [tex](2\times 0.229\times 6.022\times 10^{23})=2.76\times 10^{23}[/tex] number of aluminium atoms, [tex](3\times 0.229\times 6.022\times 10^{23})=4.14\times 10^{23}[/tex] of sulfur atoms and [tex](12\times 0.229\times 6.022\times 10^{23})=1.65\times 10^{24}[/tex] number of oxygen atoms.
- For E: 0.1250 mg of caffeine
Given mass of caffeine = 0.1250 mg = [tex]0.125\times 10^{-3}[/tex] g (Conversion factor: 1 g = 1000 mg)
Molar mass of caffeine = 194.2 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of caffeine}=\frac{0.125\times 10^{-3}g}{194.2g/mol}=6.44\times 10^{-7}mol[/tex]
1 mole of caffeine contains 8 moles of carbon element, 10 moles of hydrogen element, 4 moles of nitrogen element and 2 moles of oxygen element.
So, [tex]6.44\times 10^{-7}[/tex] moles of caffeine will contain [tex](8\times 6.44\times 10^{-7}\times 6.022\times 10^{23})=3.10\times 10^{18}[/tex] number of carbon atoms, [tex](10\times 6.44\times 10^{-7}\times 6.022\times 10^{23})=3.88\times 10^{18}[/tex] of hydrogen atoms, [tex](4\times 6.44\times 10^{-7}\times 6.022\times 10^{23})=1.55\times 10^{18}[/tex] of nitrogen atoms and [tex](2\times 6.44\times 10^{-7}\times 6.022\times 10^{23})=7.76\times 10^{17}[/tex] number of oxygen atoms.
The moles of atoms in a substance determined by dividing the mass of the substance by the molar mass of the substance.
How can moles of a substance be calculated?
The moles of a substance is calculated using the formula below:
- moles = mass/molar mass
The molar mass of the given substances are as follows:
- Potassium bromide = 119 g/mol
- H3PO4 = 98 g/mol
- CaCO3 = 100 g/mol
- Al2(SO4)3 = 342 g/mol
- C8H10N4O2 = 194 g/mol
The number atoms in each substance is calculated using the formula below:
- number of atoms = moles × 6.02 × 10^23
a. Moles of 2.12 g of KBr = 2.12/119 = 0.0178 moles
KBr contains K atoms and Br atoms
number of atoms of K = 0.0178 × 6.02 × 10^23 = 1.07 × 10^22 atoms
number of atoms of Br = 0.0178 × 6.02 × 10^23 = 1.07 × 10^22 atoms
b) Moles of 0.1488 g of H3PO4 = 0.1488/98 = 0.00151 moles
H3PO4 contains 3 moles of H atoms, 1 mole of P and 4 moles of O atoms
number of atoms of H = 3 × 0.00151 × 6.02 × 10^23 = 2.73 × 10^21 atoms
number of atoms of P = 0.00151 × 6.02 × 10^23 = 9.09 × 10^20 atoms
number of atoms of 0 = 4 × 0.00151 × 6.02 × 10^23 = 3.64 × 10^21 atoms
(c) Moles of 23 kg of CaCO3 = 23 × 1000/100 = 230 moles
CaCO3 contains 1 mole of Ca atoms, 1 mole of C atoms and 3 moles of O atoms
number of atoms of Ca = 230 × 6.02 × 10^23 = 1.38 × 10^26 atoms
number of atoms of C = 230 × 6.02 × 10^23 = 1.38 × 10^26 atoms
number of atoms of O = 3 × 230 × 6.02 × 10^23 = 4.15 × 10^26 atoms
(d) Moles of 78.452 g of Al2(SO4)3 = 78.452/342 = 0.23 moles
Al2(SO4)3 contains 2 moles of Al atoms, 3 moles of S atoms and 12 moles of O atoms
number of atoms of Al = 2 × 0.23 × 6.02 × 10^23 = 2.76 × 10^23 atoms
number of atoms of S = 3 × 0.23 × 6.02 × 10^23 = 4.15 × 10^23 atoms
number of atoms of O = 12 × 0.23 × 6.02 × 10^23 = 1.66 × 10^24 atoms
e) Moles of 0.125 mg of C8H10N4O2 = (0.125/1000)/194 = 6.44 × 10^-7 moles
C8H10N4O2 contains 8 moles of C atoms, 10 moles of S
H atoms, 4 moles of N atoms and 2 moles of O atoms
number of atoms of C = 8 × 6.44 × 10^-7 × 6.02 × 10^23 = 3.10 × 10^18 atoms
number of atoms of H = 10 × 6.44 × 10^-7 × 6.02 × 10^23 = 3.88 × 10^18 atoms
number of atoms of N = 4 × 6.44 × 10^-7 × 6.02 × 10^23 = 1.55 × 10^18 atoms
number of atoms of O = 2 × 6.44 × 10^-7 × 6.02 × 10^23 = 7.75 × 10^17 atoms.
In conclusion, the moles of atoms are calculated from the mass and molar mass of the substances.
Learn more about moles at: https://brainly.com/question/15356425