Answer:
ΔH = 249 kJ/mol
Explanation:
The balanced reaction is:
2H₂O(g) → 2H₂(g) + O₂(g) (1)
To calculate the energy change to obtain one mole of H₂(g) from one mole of H₂O(g), the coefficients of the reaction (1) must be halved:
H₂O(g) → H₂(g) + 1/2O₂(g) (2)
The enthalpy of the reaction (2) is given by:
<em>Where 
: is the bond enthalpy of reactants and 
: is the bond enthalpy of products.</em>
<u>For the reactants we have the next bond energies:</u>
2 x (H-O) = 2 x (467)
<u>And the bond energies for the products are:</u>
H-H + (1/2) (O=O) = 436 + (1/2)(498)
So, the enthalpy of the reaction (2) is:
I hope it helps you!
An echo is an example of the <em>reflection</em> of sound waves.
Answer:
Explanation:
R² = F₁² + F₂² + 2F₁F₂ Cosθ , R is resultant force , θ is angle between them
780² = 390² + 550² + 2 x 390 x 550 Cosθ
608400 = 152100 + 302500 + 429000 Cosθ
Cosθ = .3585
θ = 69 degree.
Answer:
Car A is not accelerating, but car B is accelerating
Explanation:
Car A is not accelerating because , it is moving with uniform speed in a particular direction . Therefore its velocity too is not changing .
But car B is accelerating because , though its speed is uniform but its velocity is changing due to change in direction . On a circular path , direction of speed changes every moment . Therefore it has an acceleration called centripetal acceleration . Hence car B has acceleration.
