The answer is chemical change
That is exploding of potassium metal when placed in water is chemical change.
When potassium is dropped into a beaker full of water then potassium moves about rapidly and then ignites within seconds, that is the metal is gone and all activity ceases.
So it an example of chemical change.
The reaction of potassium with water is as follows:
2K + 2H₂O ---->2KOH + H₂
Answer:
0.55 atm
Explanation:
According to Dalton's law of partial pressures,
The total pressure is the summation of the partial pressures of individual gases in a sample of non-reactive gases.
Since Neon and Argon are noble gases, they do not react with each other. So we can apply Dalton's partial pressure law.
P total = P Ar + P Ne
2.39 atm = P Ar+ 1.84 atm
P Ar = 2.39 atm - 1.84 atm
= 0.55 atm
Answer:
A i. Internal energy ΔU = -4.3 J ii. Internal energy ΔU = -6.0 J B. The second system is lower in energy.
Explanation:
A. We know that the internal energy,ΔU = q + w where q = quantity of heat and w = work done on system.
1. In the above q = -7.9 J (the negative indicating heat loss by the system). w = 3.6 J (It is positive because work is done on the system). So, the internal energy for this system is ΔU₁ = q + w = -7.9J + 3.6J = -4.3 J
ii. From the question q = +1.5 J (the positive indicating heat into the system). w = -7.5 J (It is negative because work is done by the system). So, the internal energy for this system is ΔU₂ = q + w = +1.5J + (-7.5J) = +1.5J - 7.5J = - 6.0J
B. We know that ΔU = U₂ - U₁ where U₁ and U₂ are the initial and final internal energies of the system. Since for the systems above, the initial internal energies U₁ are the same, then we say U₁ = U. Let U₁ and U₂ now represent the final energies of both systems in A i and A ii above. So, we write ΔU₁ = U₁ - U and ΔU₂ = U₂ - U where ΔU₁ and ΔU₂ are the internal energy changes in A i and A ii respectively. Now from ΔU₁ = U₁ - U, U₁ = ΔU₁ + U and U₂ = ΔU₂ + U. Subtracting both equations U₁ - U₂ = ΔU₁ - ΔU₂
= -4.3J -(-6.0 J)= 1.7 J. Since U₁ - U₂ > 0 , U₂ < U₁ , so the second system's internal energy increase less and is lower in energy and is more stable.
The a<span>tomic mass of helium is 4.002642g/mol </span>
<span>(542000g)/(4.002642g/mol)*6.02*10^23 = 8.15*10^28 atoms
If you don't understand comment, not everyone understands what the / and * mean ^.^</span>