Answer:
46.9mg of oxygen
Explanation:
From Henry's law,
Concentration of oxygen (C) = Henry's constant (K) × partial pressure of oxygen in air (p)
K = 1.3×10^-3M/atm O2, p = mole fraction of oxygen in air × pressure of air = 0.21×1.08atm = 0.2268atm
C = K×p = 1.3×10^-3 × 0.2268 = 0.00029484M of O2
Concentration (C) = number of moles of oxygen (n)/volume of water (V)
Volume of water (V) = 4.97L
n = CV = 0.00029484 × 4.97 = 0.001465mole
number of moles (n) = mass of O2/MW of O2
mass of O2 = number of moles of O2 × MW of O2 = 0.001465mole × 32g/mole = 0.0469g = 0.0469×1000mg = 46.9mg (to three significant figures)
Have 7 valence electrons, allowing them to more easily achieve an octet of electrons and become stable.
Answer:
8.9x10¹⁷ atoms of Al are present
Explanation:
To find the number of atoms from the mass of an atom we must convert, as first, the mass to moles using the molar mass of the atom (26.98g/mol For Aluminium).
Then, we must convert the moles to atoms knowing that 1mol = 6.022x10²³ atoms.
<em>Moles Aluminium:</em>
4.0x10⁻⁵g * (1mol / 26.98g) = 1.483x10⁻⁶ moles Al
<em>atoms:</em>
1.483x10⁻⁶ moles Al * (6.022x10²³ atoms / mol) =
<h3>8.9x10¹⁷ atoms of Al are present</h3>