I think it 2.25 or somethingg
-2.5089 kJ is the amount of heat is released by the combustion of the naphthalene.
<h3>How we calculate the released heat?</h3>
Released amount of heat is calculated by using the below formula:
Q = -mcΔT, where
m = mass of naphthalene = 0.25g
c = specific heat of calorimeter = 4.13 kJ/°C
ΔT = change in temperature = 26.43°C - 24°C = 2.43°C
Putting all these values in the above equation, we get
Q = - (0.25 × 4.13 × 2.43) = - 2.5089 kJ
Hence, - 2.5089 kJ heat is released.
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On Earth it is relatively rare—5.2 ppm by volume in the atmosphere. Most terrestrial helium<span> present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium, although there are other examples), as the alpha particles emitted by such decays consist of </span>helium<span>-4 nuclei.</span>
For 1. 00 l of an aqueous buffer containing 60. 0 mmol of acetic acid (pa=4. 76) and 40. 0 mmol of acetate, the pH of this buffer is 4.58.
<h3>What is handerson Hasselbalch equation? </h3>
It is expressed as:
pH = pKa + log [A-]/[HA]
where,
[A-] is the molar concentration of conjugate base
[HA] is the molar concentration of weak acid
Given,
pKa = 4.76
<h3>Calculation of concentration:</h3>
C = n/V
= 60/1000
= 0.06M
C = 40/1000
= 0.04M
Now, substituting values in equation we get,
pH = 4.76 + log(0.04/0.06)
pH = 4.76 + (-0.176)
pH = 4.58
Thus by using Henderson Hasselbalch equation we find the value of pH of the buffer is 4.58.
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Sugar is 51.16% oxygen because 41.86 + 6.98 = 48.84, minus that from 100 gets 51.16.
