Answer:
D
Explanation:
There is know graph that has the information to answer this question.
Nₐ=6.02*10²³ mol⁻¹
n(Na₂O)=0.5 mol
n(Na⁺)=2n(Na₂O)
N(Na⁺)=n(Na⁺)Nₐ=2n(Na₂O)Nₐ
N(Na⁺)=2*0.5*6.02*10²³=6.02*10²³ ions
<h3>
Answer:</h3>
250.756 moles He
<h3>
Explanation:</h3>
From the question we are given;
Volume, L = 685 L
Temperature, T = 621 K
Pressure, P = 189 × 10 kPa
We are required to calculate the number of moles of the gas,
Using the Ideal gas equation,
PV = nRT, where P is the pressure, V is the volume, T is the temperature, n is the number of moles, and R is the ideal gas constant.
We can replace the known variables and constant in the equation to get the unknown variable, n.
Using ideal gas constant as 8.3145 L.kPa/K/mol
![n=\frac{PV}{RT}](https://tex.z-dn.net/?f=n%3D%5Cfrac%7BPV%7D%7BRT%7D)
![n=\frac{(1890)(685)}{(8.3145)(621)}](https://tex.z-dn.net/?f=n%3D%5Cfrac%7B%281890%29%28685%29%7D%7B%288.3145%29%28621%29%7D)
![n = 250.7557 moles](https://tex.z-dn.net/?f=n%20%3D%20250.7557%20moles)
n = 250.756 moles
The moles of helium contained in the sphere is 250.756 moles
Answer:
a) ΔU = 370 KJ
b) Endothermic
Explanation:
a)
The change in energy of the mixture can be given by first law of thermodynamics as:
ΔQ = ΔU + W
ΔU = ΔQ - W
where,
ΔQ = change in heat energy of system
ΔU = Change in internal energy of gases
W = Work done on gases = - 155 KJ
For an isobaric process (i.e constant pressure) we know that:
ΔQ = change in enthalpy = ΔH
ΔQ = 215 KJ
Therefore, using values in the equation, we get:
ΔU = 215 KJ - (-155 KJ)
<u>ΔU = 370 KJ</u>
b)
Since, the enthalpy of products is greater than the reactants. Therefore, this is an <u>endothermic reaction</u>.