Negative enthalpy are moving to the side of the spontaneous reaction
Answer:
gain at least one electron
The
equation for the photosynthesis reaction in which carbon dioxide and water
react to form glucose is .
The hear reaction is the difference between the bond dissociation energies in
the products and the bond dissociation energies of the reactants
The
reactant molecules have 12 C = O, 12 H - O bonds while the product molecules
have 5 C - C, 7 C – O, 5 H – O, and 6 O = O bonds. The average bond
dissociation energies for the bonds involved in the reaction are 191 for C = O,
112 for H – O, 83 C –C, 99 C – H, 86 C – O, 119 O = O.
Substitute
the average bond dissociation energies in the equation for and
calculate as follows
=
[12 (C=O) + 12 (H-O)] – [5(C-C) + 7(C-H) + 7 (C-O) + 5(H-O) + 6(O=O)]
=
[12x191 kcal/mol + 12x112 kcal//mol] – [5x83 kcal/mol + 7x99 kcal/mol + 7x86
kcal/mol + 5x112 kcal/mol + 6x119 kcal/mol]
=
3636 kcal/mol – 2984 kcal/mol = 652 kcal/mol x 4.184 Kj/1kcal = 2.73x10^3 kJ/mol
So,
enthalpy change for the reaction is 652 kcal/mol or 2.73x10^3 kJ/mol
<span> </span>
Answer:
18 g
Explanation:
Step 1: Write the balanced equation
2 Al + 6 HCl ⇒ 2 AlCl₃ + 3 H₂
Step 2: Calculate the moles of Al
The molar mass of Al is 26.98 g/mol.
28.1 g × 1 mol/26.98 g = 1.04 mol
Step 3: Calculate the moles of HCl
46 mL of 1 M HCl react.
0.046 L × 1 mol/L = 0.046 mol
Step 4: Determine the limiting reactant
The theoretical molar ratio of Al to HCl is 2:6 = 0.33:1.
The real molar ratio of Al to HCl is 1.04:0.046 = 22.6:1
According to this, the limiting reactant is HCl.
Step 5: Calculate the mass of AlCl₃ generated from 0.046 moles of HCl
The molar ratio of HCl to AlCl₃ is 6:2. The molar mass of AlCl₃ is 133.34 g/mol.
0.046 mol HCl × 6 mol HCl/2 mol AlCl₃ × 133.34 g AlCl₃/1 mol AlCl₃ = 18 g AlCl₃