<span>Soda ash is sodium carbonate, Na2CO3. One chemical property of this compound is its basicity, which is measured by the pKb. The pKb for sodium carbonate is 3.67. It is the result of the dissociation of Na2CO3 in water: Na2CO3 + H2O = Na HCO3 + Na (+) + OH(-). This pKb means that it is a highly basic compound. pKb = log { 1 / [OH-] }, so pKb is a measure of the concentrations of OH- ions, which is the basiciity of the compound. </span>
Answer:
n = 2.208x10¹⁸ photons
Explanation:
The energy of a photon( an elementary particle) is given by the equation:
E = nxhxf
Where n is the number of photons, h is plank constant (6,62x10⁻³⁴ J.s), and f is the frequency. Knowing that the power level is 0.120mW (1.2x10⁻⁴ W), the energy in J, for a time of 78 min (4680 s)
E = 1.2x10⁻⁴x4680 = 0.5616 J
The frequency of a photon is its velocity ( c= 3x10⁸ m/s) divided by its wavelength, which is 780 nm = 780x10⁻⁹ m
f = 3x10⁸/780x10⁻⁹
f = 3.846x10¹⁴ s⁻¹
Then, the number of photons is:
0.5616 = nx6,62x10⁻³⁴x3.846x10¹⁴
n = 2.208x10¹⁸ photons.
The rate constant for 1st order reaction is
K = (2.303 /t) log (A0 /A)
Where, k is rate constant
t is time in sec
A0 is initial concentration
(6.82 * 10-3) * 240 = log (0.02 /A)
1.63 = log (0.02 /A)
-1.69 – log A = 1.63
Log A = - 0.069
A = 0.82
Hence, 0.82 mol of A remain after 4 minutes.
Explanation:
The rest of the energy is passed on as food to the next level of the food chain. The figure at the left shows energy flow in a simple food chain. Notice that at each level of the food chain, about 90% of the energy is lost in the form of heat.
Answer:
V = 134.5 L
Explanation:
Given data:
Number of moles of KClO₃ = 4 mol
Litters of oxygen produced at STP = ?
Solution:
Chemical equation:
2KClO₃ → 2KCl + 3O₂
Now we will compare the moles of KClO₃ with oxygen.
KClO₃ : O₂
2 : 3
4 ; 3/2×4 = 6 mol
Litters of oxygen at STP:
PV = nRT
V = nRT/P
V = 6 mol × 0.0821 atm.L/mol.K × 273 K / 1atm
V = 134.5 L / 1
V = 134.5 L
