pls help asap?

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2020-10-13 9:00 pm

An ideal gas is compressed at a constant pressure of 250 KPa to one-half of its initial volume. The work done on the gas is 820,000 J. What was the initial volume of the gas? *

Initial Volume = 0.00065 Centimetres cube

Initial Volume = 6.56 Centimetres cube

Initial Volume = 0.0065 Centimetres cube

Initial Volume = 0.6686 Centimetres cube

A gas with a constant pressure of 235 kpa expands from a volume of 4.5 cubic meters to a volume of 9.6 cubic meters. How much work does the gas do? *

W = 1,198,500 J

W = 1198 J

W = 24,000 J

W = 25,000 J

A gas at constant volume has 500 J of heat added to it. What is the work done by the gas? *

W = 500 J

W = 5 J

W = 0

W = 250 J

回答 (1)

Uncle Michael

2020-10-13 9:49 pm

✔ 最佳答案

1.
Let Vᵢ m³ be the initial volume.
Then, ΔV = [(Vᵢ/2) - Vᵢ] = -Vᵢ/2

Work done on the gas = -P ΔV
(250 × 10³ Pa) × (Vᵢ/2 m³) = 820000 J
Initial volume, Vᵢ = 6.56 m³ = 6,560,000 cm³

None of four options is the answer.

====
2.
Work done by the gas
= P ΔV
= (235 × 10³ Pa) × [(9.6 - 4.5) m³]
= 1,198,500 J

The answer: 1,198,500 J (the 1st option)

====
3.
Work done by the gas
= P ΔV
= P × 0
= 0

The answer: 0 (the 3rd option)

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