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:
Explanation:
Please, find the image with the pictured molecule for this question attached.
The molecule has one oxygen atom (red) covalently bonded to one hydrogen atom (light grey), one nitrogen atom (blue) covalently bonded to two hydrogen atoms (light grey), and two carbon atoms (dark grey) bonded each to two hydrogen atoms (light grey).
<em>Hydrogen bondings</em> are intermolecular bonds (bonds between atoms of two different molecules not between atoms of the same molecule). The hydrogen bonds are attractions between the positive end of one hydrogen atom and the negative end of a small atom of other molecule (N, O, or F).
Since, nitrogen and oxygen are much more electronegative than hydrogen atoms, you conclude that:
- The two hydrogen atoms covalently bonded to the nitrogen atoms have considerably partial positive charge.
- The hydrogen atom covalently bonded to the oxygen atom also has a a relative large partial positive charge.
So, those are three ends of the molecule that can form hydrogen bonds with water molecules.
The hydrogen bondings are only possible when hydrogen is covalently bonded to N, O or F atoms.
Those elements with similar properties are in the same column.
