How many moles of Fe2+ are there in a 2.0g sample that is 80% by mass of FeCl2?
1 answer:
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Answer:
34,6g of (NH₄)₂SO₄
Explanation:
The boiling-point elevation describes the phenomenon in which the boiling point of a liquid increases with the addition of a compound. The formula is:
ΔT = kb×m
Where ΔT is Tsolution - T solvent; kb is ebullioscopic constant and m is molality of ions in solution.
For the problem:
ΔT = 109,7°C-108,3°C = 1,4°C
kb = 1.07 °C kg/mol
Solving:
m = 1,31 mol/kg
As mass of X = 600g = 0,600kg:
1,31mol/kg×0,600kg = 0,785 moles of ions. As (NH₄)₂SO₄ has three ions:
0,785 moles of ions× = 0,262 moles of (NH₄)₂SO₄
As molar mass of (NH₄)₂SO₄ is 132,14g/mol:
0,262 moles of (NH₄)₂SO₄× = <em>34,6g of (NH₄)₂SO₄</em>
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Answer:
Explanation:
Since it first order, we use order rate equation
In ( ) = -kt where A1 is the final quality = 0.8 (80%), A0 is the initial quality = 1 ( 100%)
also, t half life = where k is rate constant
k = = 0.0154
In ( ) = - 0.0154 t
-0.223 / -0.0154 = t
t = 14.49 approx 14.5 days from the date the yogurt was packaged