Answer:
455 Kcal
Explanation:
2Cl2(g) + 7O2(g) + 130kcal → 2Cl2O7(g)
Rearranging we get,
2Cl2(g) + 7O2(g) → 2Cl2O7(g) Δ H = 130 kcal . mol⁻¹
So for per mol reaction will be as above.
In case of 7 mols of product, we need 7/2 mole ratio x 130 = 455 Kcal
Answer:-3463 kJ and -3452kJ
Explanation:
ΔU is the change in internal energy of a system and its formula is;
ΔU = q + w
Where q represents heat transferred into or out of the system. Its value is positive when heat is transfer into the system and negative when heat is produced by the system.
W represents the work done on or by the system. Its value is positive when work is done on the system and negative when it is done by the system.
For the system in this question, we see that it produces heat which means heat is transferred out of the system, therefore the value of q is negative, it can also be seen that work is done by the system which means that w is also negative.
Therefore,
ΔU = -q-w
ΔU = -3452 kJ – 11kJ
= - 3463kJ
ΔH is the change in the enthalpy of a system and its formuls is;
ΔH = ΔU + Δ(PV)
By product rule Δ(PV) becomes ΔPV + PΔV
At constant pressure ΔP = 0. Therefore,
ΔH = -q-w + PΔV
w is equals to PΔV, So:
ΔH = -q
ΔH = -3452kJ
Answer:
Therefore it will take 7.66 hours for 80% of the lead decay.
Explanation:
The differential equation for decay is


Integrating both sides
ln A= kt+c₁

[
]
The initial condition is A(0)= A₀,


.........(1)
Given that the
has half life of 3.3 hours.
For half life
putting this in equation (1)

[taking ln both sides,
]

⇒k= - 0.21
Now A₀= 1 gram, 80%=0.8
and A= (1-0.8)A₀ = (0.2×1) gram = 0.2 gram
Now putting the value of k,A and A₀in the equation (1)




⇒ t≈7.66
Therefore it will take 7.66 hours for 80% of the lead decay.
The solid form of a substance is usually more dense than its
liquid and gaseous forms. Similarly the liquid form is usually more dense than
the gaseous form. Ice floating in water is an exception that breaks the general
density rule. So option “A” is the correct option in regards to the given
question. In case of ice formation, actually the density of water decreases by
about 9%. This is the main reason behind ice floating in water. Pure water has
the maximum density at 4 degree centigrade.