Hey there!
Given the reaction:
B + H⁺ => HB⁺
At half-equivalence point : [B] = [HB⁺]
=> [B] / [HB⁺] = 1
Henderson-Hasselbalch equation :
pH = pKa + log ( [B] ) / ( HB⁺)]
pH = 14 - pKb + log ( 1 )
pH = 14 - 7.95 + 0
pH = 6.05
Answer C
Hope that helps!
To solve this question,
let us first calculate how much all the nucleons will weigh when they are apart,
that is:
<span>Mass of 25 protons = 25(1.0073) = 25.1825 amu </span>
Mass of neutrons = (55-25)(1.0087) = 30.261 amu
So, total mass of nucleons = 30.261+25.1825 =
55.4435 amu
<span>Now we subtract the mass of nucleons and mass of the Mn
nucleus:
55.4435 - 54.938 = 0.5055 amu
This difference in mass is what we call as the mass defect of
a nucleus. Now we calculate the binding energy using the formula:</span>
<span> E=mc^2 </span>
<span>But first convert mass defect in units of SI (kg):
Δm = 0.5055 amu = (0.5055) / (6.022x10^26)
<span>Δm = 8.3942x10^-28 kg</span>
Now applying the formula,
E=Δm c^2
E=(8.3942x10^-28)(3x10^8)^2
E=7.55x10^-11 J</span>
Convert energy from Joules
to mev then divide by total number of nucleons (55):
E = 7.55x10^-11 J *
(6.242x10^12 mev / 1 J) / 55 nucleons
<span>E = 8.57 mev / nucleon</span>
Since you did not give a calculation,
I will just give an example. Suppose that you are to burn 5 kg of methane (CH4)
from 0 to 10°C. The specific heat capacity of methane is 4.475 kJ/kg-K.
H
= mCpT
H
= (5kg)( 4.475 kJ/kg-K)(10-0)
H = 223.75 kJ
Because the enthalpy is positive
in value, methane takes in heat.
Because many animals are likely to die from contamination
