Redox reactions

用戶16766

2007-06-16 1:48 am

Redox reactions used to thrust rockets:
Reaction A: N2H4(g) + 2H2O2(g) → N2(g) + 4H2O(g)
Reaction B: 2H2(g) + O2(g) → 2H2O(g)
(a) In Reactions A and B :number of moles of reactants and products=?
(b) Reactions used to propel rockets need to produce large volumes of gas.Use the information in(a)to suggest why reaction A is more likely to be used to propel rockets.
Explain why gas volumes measured at r.t.p. cannot be used in calculations for gases produced in rocket engines.

回答 (1)

志仁

2007-06-16 2:13 am

✔ 最佳答案

a) In reation A: 1 mol of N2H4(g) and 2 mol of H2O2(g) become 1 mol of N2(g) and 4 mol of H2O(g) (3 mol reactant become 5 mol product)
In reation B: 2 mol of H2(g) and 1 mol of O2(g) become2 mol of H2O(g) (3 mol reactant become 2 mol product)
b) The volume of gas increased after reaction, the rocket can expel more gas by taking lesser fuel. (3 become 5) since the acceleration of the rocket is depends on the volume and speed of gas expel, the faster and more gas expel, the larger the acceleration.
At the rocket, gases are expel at a very high temperature, the pressure are different from at RTP. The hotter of the gas, the higher the pressure, and the volume of gases depends on pressure and temperature. PV=nRT, P-pressure, V-volume, n-no. of mole of gases, R-constant and T-temperature.

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