Answer: 
Explanation:
The balanced chemical equation :
To calculate the moles, we use the equation:

According to stoichiometry:
4 moles of
produces = 902.0 kJ of energy
415.1 moles of
produces =
of energy
Thus the change in enthalpy is 
Answer:
The velocity of the particle is 2 m/s,
Explanation:
Kinetic energy is defined as energy of the body due to its motion. It is given by :

Where :
m = mass of the object
v = velocity of the object
We have , particle with mass m and its kinetic energy is twice its mass.




And unit of velocity are m/s , so the velocity of the particle is 2 m/s.
D
Avogadro's number allows us to measure the amount of atoms or molecules in one mole of a substance.
Answer:- 64015 J
Solution: There is 4250 mL of water in the calorimeter at 22.55 degree C.
density of water is 1 g per mL.
So, the mass of water =
= 4250 g
Final temperature of water after adding the hot copper bar to it is 26.15 degree C.
So,
for water = 26.15 - 22.55 = 3.60 degree C
Specific heat for water is 4.184 
The heat gained by water is calculated by using the formula:

where, q is the heat energy, m is mass and c is specific heat.
Let's plug in the values in the formula and do the calculations:

q = 64015 J
So, 64015 J of heat is gained by the water.
it´s actually Lithium and fluorine / Magnesium and Chlorine / Beryllium and Nitrogen