D. F
Molecules are a group of bonded atoms but Fluorine stands on its own
<span>Answer: 100 ml
</span>
<span>Explanation:
1) Convert 1.38 g of Fe₂S₃ into number of moles, n
</span>i) Formula: n = mass in grass / molar mass
<span>
ii) molar mass of </span><span>Fe₂S₃ =2 x 55.8 g/mol + 3 x 32.1 g/mol = 207.9 g/mol
</span>
iii) n = 1.38 g / 207.9 g/mol = 0.00664 moles of <span>Fe₂S₃
</span>
<span>2) Use the percent yield to calculate the theoretical amount:
</span>
<span>65% = 0.65 = actual yield/ theoretical yield =>
</span>theoretical yield = actual yield / 0.65 = 0.00664 moles / 0.65 = 0.010 mol <span>Fe₂S₃</span><span>
3) Chemical equation:
</span>
<span> 3 Na₂S(aq) + 2 FeCl₃(aq) → Fe₂S₃(s) + 6 NaCl(aq)
4) Stoichiometrical mole ratios:
</span>
<span>3 mol Na₂S : 2 mol FeCl₃ : 1 mol Fe₂S₃ : 6 mol NaCl
5) Proportionality:
</span>2moles FeCl₃ / 1 mol Fe₂S₃ = x / 0.010 mol Fe₂S₃
<span>
=> x = 0.020 mol FeCl₃
6) convert 0.020 mol to volume
</span>
<span>i) Molarity formula: M = n / V
</span>
<span>ii) V = n / M = 0.020 mol / 0.2 M = 0.1 liter = 100 ml
</span>
The limiting reactant when 5.6 moles of aluminium react with 6.2 moles of water is
water( H2O)
<u><em>Explanation</em></u>
The balanced equation is as below
2 Al +3 H2O → Al2O3 +3 H2
The mole ratio of Al :Al2O3 is 2:1 therefore the moles of Al2O3
= 5.6 x1/2 = 2.8 moles
The mole ratio of H2O: Al2O3 is 3:1 therefore the moles of Al2O3 produced
= 6.2 x1/3= 2.067 moles
since H2O yield less amount of Al2O3 , H2O is the limiting reagent.
Answer:1) Volume of
required is 55.98 mL.
2) 0.62577 grams of
is produced.
Explanation:

1) Molarity of 
Volume of 
Molarity of 
Volume of 


According to reaction, 1 mole of
reacts with 3 mole of
, then, 0.0041985 moles of
will react with:
moles of
that is 0.0125955 moles.


Volume of
required is 55.98 mL.
2)

Number of moles of
According to reaction, 3 moles of
gives 1 mole of
, then 0.004485 moles of
will give:
moles of
that is 0.001495 moles.
Mass of
=
Moles of
× Molar Mass of 
= 0.001495 moles × 418.58 g/mol = 0.62577 g
0.62577 grams of
is produced.
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