Atomic mass of helium is 4.002642g/mol
(542000g)/(4.002642g/mol)*6.02*10^23 = 8.15*10^28 atoms
River Banks? I'm not completely sure but hope this helps!
A) in pure water :
by using ICE table:
According to the reaction equation:
BaCrO4(s) → Ba^2+(aq) + CrO4^2-(aq)
initial 0 0
change +X +X
Equ X X
when Ksp = [Ba^2+][CrO4^2-]
by substitution:
2.1 x 10^-10 = X* X
∴X = √2.1 x 10*-10
∴X = 1.4 x 10^-5
∴ the solubility = X = 1.4 X 10^-5
B) In 1.6 x 10^-3 m Na2CrO4
by using ICE table:
According to the reaction equation:
BaCrO4(s) → Ba^2+(aq) + CrO4^2-(aq)
initial 0 0.0016
Change +X +X
Equ X X+0.0016
when Ksp = [Ba^2+][CrO4^2-]
by substitution:
2.1 x 10^-10 = X*(X+0.0016) by solving for X
∴ X = 1.3 x 10^-7
∴ solubility =X = 1.3 x 10^-7
The correct answer is A. CO2
hope this helps
Answer:
N₂O₄ + 14 kcal ⇄ 2NO₂.
Explanation:
Since the sign of ΔH determines either the reaction is exothermic or endothermic:
+ve, the reaction is endothermic.
-ve, the reaction is exothermic.
∵ The change of enthalpy of this reaction when proceeding left to right is + 14 kcal (+ ve sign).
∴ The reaction is endothermic, the heat is a part of the reacatnts in the reaction.
So, the reaction is:
N₂O₄ + 14 kcal ⇄ 2NO₂.
