The value of delta G at 141.0 degrees celsius for the formation of phosphorous trichloride from its constituent elements,
1 answer:
Answer:
The correct answer is option E.
Explanation:
The Gibbs free energy is given by expression:
ΔG = ΔH - TΔS
ΔH = Enthalpy change of the reaction
T = Temperature of the reaction
ΔS = Entropy change
We have :
ΔH = -720.5 kJ/mol = -720500 J/mol (1 kJ = 1000 J)
ΔS = -263.7 J/K
T = 141.0°C = 414.15 K
The Gibb's free energy of the given reaction at 141.0°C is -611.3 kJ/mol.
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Answer:
Here's what I find.
Explanation:
An indicator is usually is a weak acid in which the acid and base forms have different colours. Most indicators change colour over a narrow pH range.
(a) Litmus
Litmus is red in acid (< pH 5) and blue in base (> pH 8).
This is a rather wide pH range, so litmus is not much good in titrations.
However, the range is which it changes colour includes pH 7 (neutral), so it is good for distinguishing between acids and bases.
(b) Phenolphthalein
Phenolphthalein is colourless in acid (< pH 8.3) and red in base (> pH 10).
This is a narrow pH range, so phenolphthalein is good for titrating acids with strong bases..
However, it can't distinguish between acids and weakly basic solutions.
It would be colourless in a strongly acid solution with pH =1 and in a basic solution with pH = 8.
(c) Other indicators
Other acid-base indicators have the general limitations as phenolphthalein. Most of them have a small pH range, so they are useful in acid-base titrations.
The only one that could serve as a general acid-base indicator is bromothymol blue, which has a pH range of 6.0 to 7.6.
