Answer:
a. 0.0178 moles of KBr
0.0178 moles of K
0.0178 moles of Br
b. 1.52×10⁻³ moles of acid
4.55×10⁻³ moles of H
1.52×10⁻³ moles of P
6.07×10⁻³ moles of O
c. 229.8 moles of calcium carbonate
229.8 moles of Ca
229.8 moles of C
689.4 moles of O
d. 0.229 moles of aluminum sulfate
0.458 moles of Al
0.687 moles of S
2.75 moles of O
e. 6.43×10⁻⁷ moles of C₈H₁₀N₄O₂
5.14×10⁻⁶ moles of C
6.43×10⁻⁶ moles of H
2.57×10⁻⁶ moles of N
1.28×10⁻⁶ moles of O
Step-by-step explanation:
To determine the moles of each compound we need to know the molar mass of them
Subscripts number of compounds are the number of moles, of each atoms.
For example, H₂O. 1 mol of water has 2 moles of H and 1 mol of O.
a. KBr → 119 g/mol
We convert the mass to moles (mass/molar mass)
2.12 g / 119 g/mol = 0.0178 moles of bromide
1 mol of potassium bromide has 1 mol of K and 1 mol of Br, then 0.0178 moles of salt, will have:
0.0178 moles of K
0.0178 moles of Br
b. H₃PO₄ → 97.97 g/mol
0.1488 g / 97.97 g/mol = 1.52×10⁻³ moles of acid.
1 mol of phosphoric acid has 3 moles of H, 1 mol of P and 4 moles of O
Then 1.52×10⁻³ moles of acid. will have:
(1.52×10⁻³ . 3) / 1 = 4.55×10⁻³ moles of H
1.52×10⁻³ moles of P
(1.52×10⁻³ . 4) / 1 = 6.07×10⁻³ moles of O
c. CaCO₃ → 100.08 g/mol
23000g / 100.08 g/mol = 229.8 moles
(notice, we convert the kg to g, before)
1 mol of calcium carbonate has 1 mol of Ca, 1 mol of C and 3 moles of O
Then 229.8 moles of salt will have
229.8 moles of Ca
229.8 moles of C
(229.8 . 3) / 1 = 689.4 moles of O
d. Al₂(SO₄)₃ → 342.15 g/mol
78.452 g / 342.15 g/mol = 0.229 moles
1 mol of Al₂(SO₄)₃ has 2 moles of Al, 3 moles of S and 12 moles of O
Then 0.229 moles of sulfate will have:
(0.229 . 2) / 1 = 0.458 moles of Al
(0.229 . 3) / 1 = 0.687 moles of S
(0.229 . 12) / 1 = 2.75 moles of O
e. C₈H₁₀N₄O₂ → 194.19 g/mol
0.0001250 g / 194.19 g/mol = 6.43×10⁻⁷ moles
(Notice, we convert mg to g)
1 mol of caffeine has 8 moles of C, 10 moles of H, 4 moles of N and 2 moles of O
Then, 6.43×10⁻⁷ moles of caffeine will have:
(6.43×10⁻⁷ . 5) / 1 = 5.14×10⁻⁶ moles of C
(6.43×10⁻⁷ . 10) / 1 = 6.43×10⁻⁶ moles of H
(6.43×10⁻⁷ . 4)/1 = 2.57×10⁻⁶ moles of N
(6.43×10⁻⁷ . 2)/ 1 = 1.28×10⁻⁶ moles of O