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2 answers:
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Answer:
Explanation:
25. Boyle's Law
The temperature and amount of gas are constant, so we can use Boyle’s Law.
Data:
Calculations:
26. Ideal Gas Law
We have p, V and n, so we can use the Ideal Gas Law to calculate the volume.
pV = nRT
Data:
p = 101.3 kPa
V = 20 L
n = 5 mol
R = 8.314 kPa·L·K⁻¹mol⁻¹
Calculation:
101.3 × 20 = 5 × 8.314 × T
2026 = 41.57T
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.
