Answer:
Explanation:
It often helps to write the heat as if it were a reactant or a product in the thermochemical equation.
Then you can consider it to be 11018 "moles" of "kJ"
We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.
M_r: 32.00
2C₈H₁₈ + 25O₂ ⟶ 16CO₂ + 8H₂O + 11 018 kJ
n/mol: 7280
1. Moles of O₂
The molar ratio is 25 mol O₂:11 018 kJ
2. Mass of O₂
Answer:
C.) HOCl Ka=3.5x10^-8
Explanation:
In order to a construct a buffer of pH= 7.0 we need to find the pKa values of all the acids given below
we Know that
pKa= -log(Ka)
therefore
A) pKa of HClO2 = -log(1.2 x 10^-2)
=1.9208
B) similarly PKa of HF= -log(7.2 x 1 0^-4)= 2.7644
C) pKa of HOCl= -log(3.5 x 1 0^-8)= 7.45
D) pKa of HCN = -log(4 x 1 0^-10)= 9.3979
If we consider the Henderson- Hasselbalch equation for the calculation of the pH of the buffer solution
The weak acid for making the buffer must have a pKa value near to the desired pH of the weak acid.
So, near to value, pH=7.0. , the only option is HOCl whose pKa value is 7.45.
Hence, HOCl will be chosen for buffer construction.
A.
Physical change
Step by step explanation;:)
Answer:
Cd is oxidized during the discharge of the battery
Explanation:
Based on the reaction:
2 NiOOH + Cd + 2H₂O → 2Ni(OH)₂ + Cd(OH)₂
And knowing Oxygen and hydrogen never change its charge, we must to find oxidation state of Ni and Cd before and after the reaction:
<em>Ni:</em>
In NiOOH: 2 O = -2*2 = -4 + 1H = +1, = -4 + 1 = -3. And as the molecule is neutral, Ni is 3+
In Ni(OH)₂: OH = -1. As there are 2 OH = -2. That means Ni is +2
The Ni is gaining one electron, that means is been reduced
<em>Cd:</em>
Cd before reaction is as pure solid with oxidation state = 0
Cd after the reaction is as Cd(OH)₂: 2 OH = -2. That means Cd is +2
The Cd is loosing 2 electrons, that means is the species that is oxidized.
