Answer: Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color chage, formation of a precipitate, formation of a gas, odor change, temperature change.
Answer: The enthalpy change for formation of butane is -125 kJ/mol
Explanation:
The balanced chemical reaction is,
The expression for enthalpy change is,
![\Delta H=[n\times H_f{products}]-[n\times H_f{reactants}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5Bn%5Ctimes%20H_f%7Bproducts%7D%5D-%5Bn%5Ctimes%20H_f%7Breactants%7D%5D)
Putting the values we get :
![\Delta H=[4\times H_f_{CO_2}+5\times H_f_{H_2O}]-[1\times H_f_{C_4H_{10}}+\frac{13}{2}\times H_f_{O_2}]](https://tex.z-dn.net/?f=%5CDelta%20H%3D%5B4%5Ctimes%20H_f_%7BCO_2%7D%2B5%5Ctimes%20H_f_%7BH_2O%7D%5D-%5B1%5Ctimes%20H_f_%7BC_4H_%7B10%7D%7D%2B%5Cfrac%7B13%7D%7B2%7D%5Ctimes%20H_f_%7BO_2%7D%5D)
![-2877=[(4\times -393)+(5\times -286)]-[1\times H_f_{C_4H_{10}}+\frac{13}{2}\times 0]](https://tex.z-dn.net/?f=-2877%3D%5B%284%5Ctimes%20-393%29%2B%285%5Ctimes%20-286%29%5D-%5B1%5Ctimes%20H_f_%7BC_4H_%7B10%7D%7D%2B%5Cfrac%7B13%7D%7B2%7D%5Ctimes%200%5D)
Thus enthalpy change for formation of butane is -125 kJ/mol
Answer:
The separation between layers of atoms in the crystal is 164.52 pm.
Explanation:
Formula used
(Bragg's law)
Where :
n = an order of reflection (integer)
= wavelength of the beam incident X-ray
d = spacing between the layer
θ = incident angle ( angle between ray and scatter plane)
We have :
λ = 157 pm
θ = 28.5°
n = 1
d = ?
(Bragg's law)
The separation between layers of atoms in the crystal is 164.52 pm.
Answer:
FIREWORKS : WHEN FIREWORKS EXPLODE THEY EXPEL SMOKE WHICH IS A FORM OF GAS AND THEY LIGHT UP WHICH IS ANOTHER CHEMICAL REACTION AND OF COURSE THE WHOLE FIREWORK GETS HOT ( Temperature rises )
Explanation:
you could see your reaction happens when original substance changes in color temperature formation produces light or gas in many other things
( besides it's original form! )
answer what changed from it's original form!
ex: baking a cake:
the cake change form ( rising ) due to heat ( rising temperature )
REACTION WAS:
- formation of precipitate ( solid to settle out of a solution )
- change I'm temperature to bake the cake
Extra:
you got this!
I hope I helped even just a little!
