Answer:
- 1273.02 kJ.
Explanation:
This problem can be solved using Hess's Law.
Hess's Law states that <em>regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes. This law is a manifestation that enthalpy is a state function.</em>
- We should modify the given 3 equations to obtain the proposed reaction:
<em>6C(s) + 6H₂(g) + 3O₂(g) → C₆H₁₂O₆(s),</em>
<em></em>
- We should multiply the first equation by (6) and also multiply its ΔH by (6):
6C(s) + 6O₂(g) → 6CO₂(g), ∆H₁ = (6)(–393.51 kJ) = - 2361.06 kJ,
- Also, we should multiply the second equation and its ΔH by (6):
6H₂(g) + 3O₂(g) → 6H₂O(l), ∆H₂ = (6)(–285.83 kJ) = - 1714.98 kJ.
- Finally, we should reverse the first equation and multiply its ΔH by (- 1):
6CO₂(g) + H₂O(l) → C₆H₁₂O₆(s) + 6O₂(g), ∆H₃ = (-1)(–2803.02 kJ) = 2803.02 kJ.
- By summing the three equations, we cam get the proposed reaction:
<em>6C(s) + 6H₂(g) + 3O₂(g) → C₆H₁₂O₆(s),</em>
<em></em>
- And to get the heat of reaction for the production of glucose, we can sum the values of the three ∆H:
<em>∆Hrxn = ∆H₁ + ∆H₂ + ∆H₃ =</em> (- 2361.06 kJ) + (- 1714.98 kJ) + (2803.02 kJ) = <em>- 1273.02 kJ.</em>
Answer:
The freezing of water into ice causes the cracks to widen because it occupy more space.
Explanation:
When the water change its state of liquid to solid state due to decrease in temperature, it contracts means occupy less space but when the temperature reaches to 4 degree Celsius, it starts to expand. When the temperature goes below 0 degree Celsius, it will cause more expansion and occupy more space that causes the cracks to widen.
power = work/time
watt = joule/sec
a) power = 0.10 watt = 0.1joules/sec
work = power * time
= 0.10 * 1 =0.1joules
work is northing but energy
therefore energy is 0.1joules
according to planks quantum theory E = nhν where nis the no. of photons ; h is planks constant; ν isfrequency
hence, n = E/hν
or n = Eλ/hc (ν = c/λ)
n = (0.1*700*10^-9)/6.625*10^-34*3*10^8 = 0.3522*10^18photons
b) similar to the above calculation
here E = 1.0joules
n = (1.0*700*10^-9)/6.625*10^-34*3*10^8 = 0.3522*10^17photons
Energy= 2381 joules
heat= Mass(kg) *change in temperature(K) * Cp
2381=0.155*(15)*Cp
Cp=1024 J/kg K
