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 only one example of a chemical change would be:
B. Leaving cheese out to get moldy.
Because there is a chemical reaction.
New molecules would form.
the other three are examples of a physical change
Answer:
The rate constant at T = 100 C is 1.0*10⁻³
Explanation:
The Arrhenius equation relates two rate constants K1 and K2 measured at temperatures T1 and T2 as shown below:
here, ΔHrxn = standard enthalpy change of the reaction
R = gas constant
From the given information:
K1 = 7.4*10^-4
T1 = 25 C = 25+273 = 298 K
T2 = 100 C = 100+273 = 373K
ΔH°=4.1kJ/mol
K2 = 1.03*10⁻³
Answer:
false
Explanation:
standard form is Potassium hydrogen phthalate
