Respuesta :
Question:
100.0mL of 0.40M Al(NO₃)₃ is reacted with 100.0 mL of 0.40M KOH according to
the following reaction: Al(NO₃)₃ + 3KOH → Al(OH)₃ + 3KNO₃
Answer:
1) KOH
2) Al(NO₃)₃
3) 0.01333 moles or 1.04004 g of Al(OH)₃
4) The amount of the excess reactant, Al(NO₃)₃ left after the reaction = 2/75 moles or 5.6799 grams of Al(NO₃)₃
5) The percentage yield of Al(OH)₃ is 48.075%
Explanation:
1) The reaction is given as follows;
Al(NO₃)₃ + 3KOH → Al(OH)₃ + 3KNO₃
One mole of Al(NO₃)₃ reacts with three moles of 3KOH to produce one mole of Al(OH)₃ and three moles of 3KNO₃
Hence when 0.4 moles of Al(NO₃)₃ reacts with 0.4 moles of KOH, the limiting reagent is found as follows;
1/3 moles Al(NO₃)₃ combines with 1 moles of KOH
Hence 0.4/3 moles of Al(NO₃)₃ will combine with 0.4 moles of KOH from which there will be an excess of (0.4 - 0.4/3) moles of Al(NO₃)₃ left, making KOH the limiting reactant
2) The excess reactant as shown above is the Al(NO₃)₃
3) From the reaction above, 0.4 moles of KOH combined with excess Al(NO₃)₃ will produce 0.4/3 moles of Al(OH)₃ however, since the reagent are each 100 mL, and 0.40 M indicates 0.4 moles per 1000 mL the number of moles of Al(OH)₃ produced is given as follows;
0.4/3 = 2/15 moles per 1000 mL ≡ 2/15 ÷ 10 = 2/150 moles per 1000 mL ÷ 10 or 100 mL
The number of moles of Al(OH)₃ produced = 2/150 = 0.01333 moles
Molar mass of Al(OH)₃ = 78.003 g/mol
Mass of Al(OH)₃ produced = Number of moles produced × Molar mass
Mass of Al(OH)₃ produced = 0.01333 × 78.003 = 1.04004 g
4) The amount of the excess reactant, Al(NO₃)₃ left after the reaction is found as follows;
0.4 - 0.4/3 = 2/5 - 2/15 = 4/15 moles of Al(NO₃)₃ per 1000 mL or 4/(15×10) =2/75 moles per 100 mL
Molar mass of Al(NO₃)₃ 212.996238 g/mol
Mass left = Number of moles × Molar mass = 5.6799 grams
The amount of the excess reactant, Al(NO₃)₃ left after the reaction = 2/75 moles or 5.6799 grams of Al(NO₃)₃
5) If 0.50 g of Al(OH)₃ is produced, we have
Actual yield = 0.01333 moles of Al(OH)₃
Molar mass of Al(OH)₃ = 78.003 g/mol
Mass of theoretical yield = Molar Mass × Theoretical yield = 0.01333 × 78.003 = 1.04004 g of Al(OH)₃
Therefore;
[tex]Percentage \ yield = \frac{Actual \, yield}{Theoretical \, yield} \times 100 = \frac{0.5}{1.04004} \times 100 = 48.075 \%[/tex]
The percentage yield of Al(OH)₃ = 48.075%.