The standard enthalpy of formation of substance in its standard state is zero.
Enthalpy is defined as a thermodynamic quantity that describes the energy of a system. For substances in their standard state, the enthalpy of formation is zero.
The standard state of a substance is defined as the state in which it is found under standard conditions. The following substances has their standard ethalpy of formation as zero or not zero;
Zero enthalpy of formation Non zero enthalpy of formation
Cl2(g) I2(s)
Br(g) Br2(l)
I2(g) Br2(s)
Hg(l) Hg(s)
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Answer:
6.25 grams is the mass of solute dissolved.
Explanation:
w/w % : The percentage mass or fraction of mass of the of solute present in total mass of the solution.
Mass of the solution = 50.0 g
Mass of the solvent = x
w/w % = 12.5%
x = 6.25 g
6.25 grams is the mass of solute dissolved.
Answer:
1.44 x 10²⁵ ions of Na⁺
Explanation:
Given parameters:
Mass of NaCl = 1.4kg = 1400g
Unknown:
Number of ions of sodium = ?
Solution:
The compound NaCl in ionic form can be written as;
NaCl → Na⁺ + Cl⁻
In 1 mole of NaCl we have 1 mole of sodium ions
Now, let us find the number of moles in NaCl;
Number of moles =
Molar mass of NaCl = 23 + 35.5 = 58.5g/mol
Number of moles = = 23.93mol
So;
Since 1 mole of NaCl gives 1 mole of Na⁺
In 23.93 mole of NaCl will give 23.93 mole of Na⁺
1 mole of a substance = 6.02 x 10²³ ions of a substance
23.93 mole of a substance = 6.02 x 10²³ x 23.93
= 1.44 x 10²⁵ ions of Na⁺