How to find amount of work done in a steam engine?

Steam engines have been extremely important devices. To get a sense of why, answer the following question: How much work is done when 18.0g of liquid water is vaporized at 100C against a constant external pressure of 101.3kpa? I can't figure out which equation to use for this question

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  • Anonymous
    8 years ago
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    Work = - P * ΔV

    You use the ideal gas law formula: PV = nRT

    Since work is the product of P and V you just need to evaluate for nRT:

    n = 18 g = 1 mol

    R = 8.314 J/(mol*K)

    T = 100 °C = 373 K

    Therefore:

    nRT = 1 mol * 8.314 J/(mol*K) * 373 K

    = 3100 J

    = 3.1 kJ

    Source(s): McGill University
  • Anonymous
    5 years ago

    Sorry this is long - but it's the BRITISH version! As this is the UK site I assume we couldn't really care less what they did/do over the water. In the UK, when trains were "double headed" it meant that two engines were coupled to the train and co-ordination between the crews was done by whistle signals, these being "set down" in the Rule Book. Under certain circumstances - e.g. when a heavy train needed assistance to climb a long bank (rising gradient), it was sometimes more expedient to literally drive another engine onto the back of the train at pre-arranged places - these were known as "banking engines" - and would simply push the train from the rear until the main train had got to the top or "over the hump" when the banking engine would simply stop pushing and would drop away from the train. It would then be signalled into a refuge siding whilst the main train went merrily on its way. The banking engine would then wait in the siding either until it was required to assist a train going down the gradient when it would join the front engine and assist with braking. If there were more than one train going "up" the slope, any number of banking engines could meet in the sidings, and all return to base coupled together as a single train. Some companies - mainly the Great Western Railway - always insisted that whatever the circumstances, the main train engine would always remain at the front of the train, so that in the event of double-heading being necessary, the second engine was always just that - the second engine, although other companies who weren't necessarilly so well off weren't too particular exactly where the help came from - front or back ! ! !

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