Answer:
Therefore it takes 8.0 mins for it to decrease to 0.085 M
Explanation:
First order reaction: The rate of reaction is proportional to the concentration of reactant of power one is called first order reaction.
A→ product
Let the concentration of A = [A]
![\textrm{rate of reaction}=-\frac{d[A]}{dt} =k[A]](https://tex.z-dn.net/?f=%5Ctextrm%7Brate%20of%20reaction%7D%3D-%5Cfrac%7Bd%5BA%5D%7D%7Bdt%7D%20%3Dk%5BA%5D)
![k=\frac{2.303}{t} log\frac{[A_0]}{[A]}](https://tex.z-dn.net/?f=k%3D%5Cfrac%7B2.303%7D%7Bt%7D%20log%5Cfrac%7B%5BA_0%5D%7D%7B%5BA%5D%7D)
[A₀] = initial concentration
[A]= final concentration
t= time
k= rate constant
Half life: Half life is time to reduce the concentration of reactant of its half.
Here 
To find the time takes for it to decrease to 0.085 we use the below equation
![\Rightarrow t=\frac{2.303}{k} log\frac{[A_0]}{[A]}](https://tex.z-dn.net/?f=%5CRightarrow%20t%3D%5Cfrac%7B2.303%7D%7Bk%7D%20log%5Cfrac%7B%5BA_0%5D%7D%7B%5BA%5D%7D)
Here , 
, [A₀] = 0.13 m and [ A] = 0.085 M
Therefore it takes 8.0 mins for it to decrease to 0.085 M
The entropy of the given reactions increases (S° > 0):
- 2C2H6(g) + 7O2(g) ----> 4CO2(g) + 6H2O(g) ---> S° > 0.
- NH4Cl(s) ----> NH3(g) + HCl(g) ---> S° > 0.
<h3>What is entropy?</h3>
Entropy measure how disordered a system is. It a measure of how dispersed or random the total energy of a system is. The symbol for entropy is S.
A system in which entropy increases is one in which S° > 0.
The entropy of a system decreases when S° < 0.
Entropy of a system increases (S° > 0) if any change results in an increase in temperature, increase in number of molecules, or an increase in volume.
Considering the given systems, the entropy changes is as follows:
- 2C2H6(g) + 7O2(g) ----> 4CO2(g) + 6H2O(g) ---> S° > 0.
- 2CO2(g) + N2(g) ---->2CO(g) + 2NO(g) --> no change
- 2N2(g) + O2(g) -----> 2N2O(g) ---> decreases
- S (s,rhombic) + 2CO(g) ----> SO2(g) + 2C (s,graphite) ---> no change
- NH4Cl(s) ----> NH3(g) + HCl(g) ---> S° > 0.
In conclusion, an increase in volume and moles of substances results in entropy increase.
Learn more about entropy at: brainly.com/question/26691503
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Answer:Thermal Energy is not a form of potential energy
Explanation:
The balanced chemical reaction is:
CH4 + 2O2 —> CO2 + 2H2O
You need to convert mass to moles (divide by molar mass):
CH4 moles = 5 / 16 = 0.31 mol
O2 moles = 5 / 32 = 0.16 mol
To figure out which reactant is limiting, divide the actual moles by the corresponding coefficient in the reaction:
CH4: 0.31 / 1 = 0.31
O2: 0.16 / 2 = 0.08
O2 is the lower number, so it is the limiting reactant. From the reaction we know it takes 2 moles of O2 to react with each mole of CH4. Therefore, for however many moles of O2 we actually have, half as many moles of CH4 will react. Since we have 0.16 mol of O2, only 0.08 mol of CH4 will react, leaving behind 0.31 - 0.08 = 0.23 mol of CH4.
Now convert back to mass (multiply by molar mass) to find the mass of CH4 remaining:
0.23 x 16 = 3.68g
The closest answer is B.
