Answer: The enthalpy of reaction is, -206.18 kJ
Explanation:-
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The final reaction is
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
Now adding (2) and (3) and subtracting (1) , we get :
Therefore, the enthalpy of reaction is, -206.18 kJ
Answer:
oxygen = 4.7 * 10^-6
Nitrogen = = 9.7 * 10^6
Explanation:
partial pressure of oxygen = 0.20 atm
partial pressure of Nitrogen = 0.80 atm
<u>calculate the mole fractions of oxygen and Nitrogen in water </u>
Temp = 298k
applying henry's law
molar conc of oxygen in water ( Coxygen )
= Kp = 1.3 * 10^-3 Mol/L.atm * 0.20 atm = 2.6 * 10^-4 Mol
molar conc of Nitrogen in water ( Cnitrogen )
= Kp = 6.8 * 10^-4 Mol/L.atm * 0.80 atm = 5.4 * 10^-4
next Given that the number of moles in 1 liter of water = 55.5 mol
therefore the mole fraction of oxygen
= 2.6 * 10^-4 / 55.5
= 4.7 * 10^-6
mole fraction of Nitrogen
= 5.4 * 10^-4 / 55.5
= 9.7 * 10^6
Answer:
1.52 g NaOH
Explanation:
The molar mass M is a physical property defined as the mass of a given substance (chemical element or chemical compound) divided by the amount of substance.
Molar mass of NaOH is 40.0 g/mol
40.0 g/mol contains 6.022 × 10²³ molecules
∴ 2.30 × 10²² molecules will contain (2.30 × 10²²) * (40.0)/6.022× 10²³
= 1.52 g NaOH
Answer:
frequency = 8.22 x 10¹⁴ s⁻¹
Explanation:
An electron's positional potential energy while in a given principle quantum energy level is given by Eₙ = - A/n² and A = constant = 2.18 x 10⁻¹⁸j. So to remove an electron from the valence level of Boron (₅B), energy need be added to promote the electron from n = 2 to n = ∞. That is, ΔE(ionization) = E(n=∞) - E(n=2) = (-A/(∞)²) - (-A/(2)²) = [2.18 x 10⁻¹⁸j/4] joules = 5.45 x 10⁻¹⁹ joules.
The frequency (f) of the wave ionization energy can then be determined from the expression ΔE(izn) = h·f; h = Planck's Constant = 6.63 x 10⁻³⁴j·s. That is:
ΔE(izn) = h·f => f = ΔE(izn)/h = 5.45 x 10⁻¹⁹ j/6.63 x 10⁻³⁴ j·s = 8.22 x 10¹⁴ s⁻¹
I found the rest of the exercise on the internet and these are the options.
"-Undifferentiated vertebrae throughout the body.
-One neck vertebra allowing up and down movement.
-Many neck vertebrae that allow for greater mobility.
<span>-Two neck vertebrae allowing up and down and sideways movement."
The correct answer would be the third. - "</span>Many neck vertebrae that allow for greater mobility." The <span>present-day organism with four limbs has a neck with several vertebrae that allow movements of rotation (mostly because of only two vertebrae at the top of the neck), and side way movements, as well as back and forth movements.</span>
