Answer:
It is <u>melting</u> which is a physical change.
Explanation:
What is another name for the galvanic cell?
2 answers:
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<u>Answer:</u> The heat capacity of calorimeter is
<u>Explanation:</u>
To calculate the number of moles, we use the equation:
Given mass of ethanol = 21.8 g
Molar mass of ethanol = 46.07 g/mol
Putting values in above equation, we get:
To calculate the enthalpy change of the reaction, we use the equation:
where,
= amount of heat released = ?
n = number of moles = 0.473 moles
= enthalpy change of the reaction = -1235 kJ/mol =
(Conversion factor: 1 kJ = 1000 J)
Putting values in above equation, we get:
To calculate the heat capacity of calorimeter, we use the equation:
where,
q = heat absorbed by the calorimeter =
c = heat capacity = ?
= change in temperature =
Putting values in above equation, we get:
Hence, the heat capacity of calorimeter is
Answer:
- Mass of NaH₂PO₄·H₂O = 8.542 g
- Mass of Na₂HPO₄ = 5.410 g
Explanation:
Keeping in mind the equilibrium:
H₂PO₄⁻ ↔ HPO₄⁻² + H⁺
We use the Henderson-Hasselbalch equation (H-H):
pH = pka +
For this problem [A⁻] = [HPO₄⁻²] and [HA] = [H₂PO₄⁻]
From literature we know that pka = 7.21, from the problem we know that pH=7.00 and that
[HPO₄⁻²] + [H₂PO₄⁻] = 0.100 M
From this equation we can <u>express [H₂PO₄⁻] in terms of [HPO₄⁻²]</u>:
[H₂PO₄⁻] = 0.100 M - [HPO₄⁻²]
And then replace [H₂PO₄⁻] in the H-H equation, <u>in order to calculate [HPO₄⁻²]</u>:
With the value of [H₂PO₄⁻],<u> we calculate [HPO₄⁻²]</u>:
[HPO₄⁻²] + 0.0381 M = 0.100 M
[HPO₄⁻²] = 0.0619 M
Finally, using the concentrations, the volume, and the molecular weights; we can calculate the weight of each substance:
- Mass of NaH₂PO₄·H₂O = 0.0619 M * 1 L * 138 g/mol = 8.542 g
- Mass of Na₂HPO₄ = 0.0381 M * 1 L * 142 g/mol = 5.410 g