Answer:
The standard change in free energy for the reaction = - 437.5 kj/mole
Explanation:
The standard change in free energy for the reaction:
4 KClO₃ (s) → 3 KClO₄(s) + KCl(s)
Given that ΔGf(KClO3(s)) = -290.9 kJ/mol;
ΔGf(KClO4(s)) = -300.4 kJ/mol;
ΔGf(KCl(s)) = -409 kJ/mol
According to Hess's law
ΔGr (Free energy change of reaction)= ∑(Product free energy - reactant free energy)
⇒ ΔGr⁰ = {3 x (-300.4) + (-409)} - {3 x (- 290.9)}
= - 901.2 - 409 + 872.7
= - 437.5 kj/mole
Answer:
3,964 years.
Explanation:
- It is known that the decay of a radioactive isotope isotope obeys first order kinetics.
- Half-life time is the time needed for the reactants to be in its half concentration.
- If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
- The half-life of the element is 5,730 years.
- For, first order reactions:
<em>k = ln(2)/(t1/2) = 0.693/(t1/2).</em>
Where, k is the rate constant of the reaction.
t1/2 is the half-life of the reaction.
∴ k =0.693/(t1/2) = 0.693/(5,730 years) = 1.21 x 10⁻⁴ year⁻¹.
- Also, we have the integral law of first order reaction:
<em>kt = ln([A₀]/[A]),</em>
where, k is the rate constant of the reaction (k = 1.21 x 10⁻⁴ year⁻¹).
t is the time of the reaction (t = ??? year).
[A₀] is the initial concentration of the sample ([A₀] = 100%).
[A] is the remaining concentration of the sample ([A] = 61.9%).
∴ t = (1/k) ln([A₀]/[A]) = (1/1.21 x 10⁻⁴ year⁻¹) ln(100%/61.9%) = 3,964 years.
Answer:
music amplifier or a loudspeaker
Explanation:
A music amplifier or a loudspeaker are a few devices that convert electrical energy into sound energy.
As it is a well known fact that energy can neither be created nor be destroyed it can only change from one form to the other. As here it is changing from electrical to sound.
Answer:
ρ = 1.08 g/cm³
Explanation:
Step 1: Given data
Mass of the substance (m): 21.112 g
Volume of the substance (V): 19.5 cm³
Step 2: Calculate the density of the substance
The density (ρ) of a substance is equal to its mass divided by its volume.
ρ = m / V
ρ = 21.112 g / 19.5 cm³
ρ = 1.08 g/cm³
The density of the substance is 1.08 g/cm³.
