(1) The melting of a crystalline solid is best depicted by the second graph. This is because, the second graph shows a horizontal line which means that for a while there was no change in temperature. This zone is the latent heat of fusion.
(2) The first graph shows the graph of a solid that is just heated but does not experience phase change. However, the second graph shows a solid that changes phase (from crystal/solid to liquid).
In chemical reactions the reactants are on the left side of the equation and the product are on the right
The last one. A bond of two or more of the same element.
The molecular formula of hydrate : CaCl₂.6 H₂O
So there are 6 molecules of H₂O
<h3>Further explanation</h3>
Given
54.7g CaCl₂ and 53.64 g H₂O
Required
The number of molecules H₂O
Solution
mol CaCl₂ :
= mass : MW
= 54.7 : 111 g/mol
= 0.493
mol H₂O :
= 53.64 : 18 g/mol
= 2.98
mol ratio H₂O : CaCl₂ :
= 2.98/0.493 : 0.493/0.493
= 6 : 1
From the reaction: <span>caco3(s) → cao(s) + co2(g) it can be seen that,
1 mol (i.e. 100 g) of CaCO3 gives 1 mol (i.e. 44 g) of CO2
Now, number of moles of CaCO3 present in reaction system,
</span>=

=

= 0.45 mol
So, 0.45 mol of CaCO3 will give 0.45 mol of CO2.
From ideal gas equation, we know that PV = nRT
V =

.
Given that, P = 645 torr = 0.8487 atm (Since, 1 atm = 760 torr)
Therefore, V =

= 34.8 l