Answer : The enthalpy change for the reaction is, 419.5 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
The given chemical reaction is,
Now we have to determine the enthalpy change for the reaction below:
By reversing and then dividing the reaction by 2, we get the enthalpy change for the reaction.
The expression will be:
Therefore, the enthalpy change for the reaction is, 419.5 kJ
Answer:
0.56
Explanation:
From the formula;
0.693/t1/2 = 2.303/t log (Ao/At)
t1/2 = half life of the C-14 = 5730 y
t = time elapsed = 4800 y
At = Activity of C-14 at time t
Ao= Activity of a living C-14 sample
0.693/5730 = 2.303/4800 log (Ao/At)
1.2 * 10^-4 = 4.8 * 10^-4 log (Ao/At)
log (Ao/At) = 1.2 * 10^-4/4.8 * 10^-4
log (Ao/At) = 0.25
Ao/At = Antilog (0.25)
Ao/At = 1.778
Hence;
At/Ao = (1.778)^-1
At/Ao = 0.56
Its a change in state of solid to liquid
the reason is that in a solid state the molecules have little kinetic energy to move and so they have restricted movement and so it remains solid
once heat is applied the molecules gain enough energy to move and so they turn into a liquid and move according to the laws of physics
hope that helps
Answer is: <span>lumps os sugar dissolving in water.
Sugar has very good solubility in water and it dissolves readily, which is </span><span>example of a physical change.
</span>Gibbs free energy (G) determines if reaction will proceed
spontaneously, if ΔG is negative, reaction is spontaneous <span>(ΔG = ΔH - T·ΔS).
</span>In other examples, reactions are spontaneous in reverse way, for example spontaneous is forming sodium chlorine from sodium metal and chlorine gas, but not sodium chloride forming sodium metal and chlorine gas, because a lot of energy is needed for that reaction.
