Answer:
moles H₂O = 10
Explanation:
The mass of Na₂CO₃⋅xH₂O is 3.837 g and the mass of Na₂CO₃ is 1.42g
Therefore the mass of xH₂O is 3.837 - 1.42 = 2.417 g
The molar mass of Na₂CO₃ is 106 g/mol and for H₂O is 18 g/mol
The moles of Na₂CO₃ and H₂O in the sample are:
Na₂CO₃ = 1.42 / 106 = 0.01340 moles
H₂O = 2.417 / 18 = 0.1343
Now using rule of three :
1 mole of Na₂CO₃ has x moles of H₂O
0.01340 moles of Na₂CO₃ has 0.1343 moles of H₂O
x = 1 * 0.1343 / 0.01340 = 10
Formula units in 450 g of 
is 1.93 × 10²⁴ formula units.
<u>Explanation:</u>
First we have to find the number of moles in the given mass by dividing the mass by its molar mass as,
Now, we have to multiply the number of moles of Na₂SO₄ by the Avogadro's number, 6.022 × 10²³ formula units/mol, so we will get the number of formula units present in the given mass of the compound.
3.2 mol × 6.022 × 10²³ = 1.93 × 10²⁴ formula units.
So, 1.93 × 10²⁴ formula units is present in 450g of Na₂SO₄.
<span>the atractions between the solute and solvent molecules must be greater than the atractions keeping the solute together and the atractions keeping the solvent togetherrr.</span>
The ml is also called as the magnetic quantum number. The value
of ml can range from –l to +l including zero. Hence all of the possible values for ml given
that l = 2 are:
<span>-2, -1, 0, + 1, + 2</span>
When iron rusts and forms iron oxide, the iron oxide has more mass than the iron because there are more iron atoms in iron oxide than in pure iron.
The process of rust occurs when pure iron is exposed to air and moisture. Rust is the oxidation of pure iron to iron II oxide (Fe2O3).
We can see that there are two iron atoms per mole of Fe2O3 whereas there is only one iron atom in each mole of pure iron.
Therefore, iron oxide has more mass than the iron because there are more iron atoms in iron oxide than in pure iron.
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