M (NaCl) = n × M = 3.75 × 58.5 =
219.375 g
M (NaCl) = 23 + 35.5 = 58.5 g/mol
Answer:
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Answer:
0.0010m SO₄²⁻
Explanation:
The freezing point depression due the addition of a solute into a pure solvent follows the equation:
ΔT = Kf×m×i (1)
<em>Where ΔT are °C that freezing point decreases (273.15K - 272.47K = 0.68K = 0.68°C). Kf is the constant of freezing point depression (1.86°C/m), m is molality of the solution (0.1778m) and i is Van't Hoff factor.</em>
Van't Hoff factor could be understood as in how many one mole of the solute (sulfuric acid, H₂SO₄), is dissociated.
H₂SO₄ dissociates as follows:
H₂SO₄ → HSO₄⁻ + H⁺
HSO₄⁻ ⇄ SO₄²⁻ + H⁺
<em>Not all HSO₄⁻ dissociates.</em>
1 Mole of H₂SO₄ dissociates in 1 mole of H⁺+ 1 mole of HSO₄⁻ + X moles of SO₄²⁻= 2 + X
Replacing in (1):
0.68°C = 1.86°C/m×0.1778m×i
2.056 = i
Moles of SO₄²⁻ are 2.056 - 2 = 0.056moles SO₄²⁻.
If 1 mole has a concentration of 0.1778m, 0.056moles are:
0.056moles ₓ (0.1778m / 1mole) =
<h3>0.0010m SO₄²⁻</h3>
Answer:
Empirical formula will be (NH₄)₃PO₄, which matches the molecular formula
Explanation:
This is the reaction:
NH₃ + H₃PO₄ → 28.2% N, 20.8% P, 8.1% H, 42.9% O
In 100 g of compound we have:
28.2 g N
20.8 g of P
8.1 g of H
42.9 g of O
Now we divide each between the molar mass:
28.2 g / 14 g/mol = 2.01 mol
20.8 g / 30.97 g/mol = 0.671 mol
8.1 g / 1 g/mol = 8.1 mol
42.9 g / 16 g/mol = 2.68 mol
And we divide again between the lowest value of moles
2.01 mol / 0.671 mol → 3
0.671 mol / 0.671 mol → 1
8.1 mol / 0.671 mol → 12
2.68 mol / 0.671 mol → 4
Molecular formula will be: N₃PH₁₂O₄ → (NH₄)₃PO₄
Empirical formula will be (NH₄)₃PO₄, which matches the molecular formula
29 protons, 34 neutrons, and if there is no charge there will be 29 electrons