What is the formula for Heptaphosphorous pentoxide?
1 answer:
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Answer:
Na₂CO₃.2H₂O
Explanation:
For the hydrated compound, let us denote is by Na₂CO₃.xH₂O
The unknown is the value of x which is the amount of water of crystallisation.
Given values:
Starting mass of hydrate i.e Na₂CO₃.xH₂O = 4.31g
Mass after heating (Na₂CO₃) = 3.22g
Mass of the water of crystallisation = (4.31-3.22)g = 1.09g
To determine the integer x, we find the number of moles of the anhydrous Na₂CO₃ and that of the water of crystallisation:
Number of moles =
Molar mass of Na₂CO₃ =[(23x2) + 12 + (16x3)] = 106gmol⁻¹
Molar mass of H₂O = [(1x2) + (16)] = 18gmol⁻¹
Number of moles of Na₂CO₃ = = 0.03mole
Number of moles of H₂O = = 0.06mole
From the obtained number of moles:
Na₂CO₃ H₂O
0.03 0.06
Simplest
Ratio 0.03/0.03 0.03/0.06
1 2
Therefore, x = 2
Answer:
3.49X10⁻¹⁷ J
Explanation:
The energy of an electron is given by the equation:
Where Z is the number of protons of the atom and n is the energy level of the electron. For Be, Z = 4.
When n tends to infinity (1/n²) tends to 0, and at this point, the electron has left the atom, so it has ionized.
The ionization energy then is the energy of the electron that left the atom less the energy of the electron in the energy level:
I.E = - (2.18x10⁻¹⁸)x4²x0 - (-(2.18x10⁻¹⁸)x4²x(1/1²))
I.E = 3.49X10⁻¹⁷ J