Answer:
a) +640 kJ/mol or +1.06x10⁻¹⁸ J
b) +276 kJ/mol
Explanation:
To dissociate the molecule, the bond must be broken, thus, it's necessary energy equal to the energy of the bond, which can be calculated by:
E = (Q1*Q2)/(4*π*ε*r)
Where Q is the charge of the ions, ε is a constant (8.854x10⁻¹²C²J ⁻¹ m⁻¹), and r is the bond length. Each one of the ions has a charge equal to 1. The elementary charge is 1.602x10⁻¹⁹C, which will be the charge of them.
1 mol has 6.022x10²³ molecules (Avogadros' number), so the energy of 1 mol is the energy of 1 molecule multiplied by it:
E = 6.022x10²³ *(1.602x10⁻¹⁹)²/(4π*8.854x10⁻¹²*2.17x10⁻¹⁰)
E = +640113 J/mol
E = +640 kJ/mol
Or at 1 molecule: E =640/6.022x10²³ = +1.06x10⁻²¹ kJ = +1.06x10⁻¹⁸ J
b) The energy variation to dissociate the molecule at its neutral atoms is the energy of dissociation less the difference of the ionization energy of K and the electron affinity of F (EA):
498 = 640 - (418 - EA)
640 -418 + EA = 498
222 + EA = 498
EA = +276 kJ/mol
Answer:
A. The same amount of heat is absorbed in both the experiments because the product of mass, specific heat capacity, and change in temperature are equal for both.
Explanation:
- The amount of heat absorbed by water (Q) can be calculated from the relation:
<em>Q = m.c.ΔT.</em>
where, Q is the amount of heat absorbed by water,
m is the mass of water,
c is the specific heat capacity of water (c = 4.186 J/g °C),
ΔT is the temperature difference (final T - initial T).
- <u><em>For trial 1:</em></u>
m = 30.0 g, c = 4.18 J/g °C, ΔT = 40.0 °C – 0.0 °C = 40.0 °C
<em>∴ Q = m.c.ΔT</em> = (30.0 g)(4.18 J/g °C)(40.0 °C) = <em>5023 J.</em>
- <u><em>For trial 2:</em></u>
m = 40.0 g, c = 4.18 J/g °C, ΔT = 40.0 °C – 10.0 °C = 30.0 °C
<em>∴ Q = m.c.ΔT</em> = (40.0 g)(4.18 J/g °C)(30.0 °C) = <em>5023 J.</em>
<em>A. The same amount of heat is absorbed in both the experiments because the product of mass, specific heat capacity, and change in temperature are equal for both. </em>
Answer:
C. The reaction rate at known reaction concentrations
Explanation:
The rate of a reaction is the measure of the speed of a chemical reaction. To find the rate constant of a reaction, the concentration of the reactants must be known.
- Reaction rate is directly proportional to the concentration of the reactants.
- The quantitative relationship between the rate of a reaction and the concentrations of reactants is expressed as the rate law.
- From this we can deduce the rate constant.
