1a4 marks
A kiln used to harden ceramics is shown below.
The internal chamber is a cube. Each side of this cube has length 0.46 m.
The chamber is sealed and full of argon. Argon behaves as an ideal gas.
a)
The kiln is initially at 20 °C.
The argon in the kiln has an initial pressure of 100 kPa.
The argon in the kiln has an initial pressure of 100 kPa.
i)
Calculate the amount of argon n in the chamber in moles.
n = .......................................... mol [2]
ii)
The temperature of the kiln is increased from 20 °C to 1300 °C.
Calculate the pressure in kPa at 1300 °C.
pressure = ...................................... kPa [2]
1b7 marks
b)
The temperature of the kiln is 1300 °C.
A single atom of argon is travelling horizontally towards the vertical side X of the chamber.
The initial speed of this atom is 990 m s–1. After collision, it rebounds at the same speed.
i)
Calculate the change in momentum Δp of this atom.
Mass of argon atom = 6.6 × 10–26 kg
Δp = ............................................ kg m s–1 [2]
ii)
Assume that this atom does not collide with any other argon atoms inside the chamber.
Instead, it travels horizontally, making repeated collisions with the opposite vertical walls of the chamber.
1
Show that the atom makes about 1000 collisions with side X in a time interval of 1.0 s.
[1]
2
Calculate the average force F on side X made by the atom.
F = ...................................... N [2]
iii)
Without calculation, explain how your answer to (ii)2 could be used to estimate the total pressure exerted by the atoms of the argon gas in the kiln.
[2]
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