Related to expansion of gas under adiabatic conditions.

Asked by archubelur2 | 5th Oct, 2010, 08:47: PM

Expert Answer:

Answer of 1 and 2:
An adiabatic process is defined as one with no heat transfer into or out of a system: dQ=0. We can prevent heat flow either by surrounding the system with thermally insulating material or by carrying out the process so quickly that there is not enough time for appreciable heat flow. From the first law, we find that for every adiabatic process,

dQ = dv + dw = 0, du = -dw

when a system expands adiabatically. dW is positive (the system does work on its surroundings), so DU is negative and the internal energy decreases. When a system is compressed adiabatically, dW is negative (work is done on the system by its surroundings) and DU increases. In many (but not all) systems, an increase of internal energy is accompanied by a rise in temperature.

The compression stroke in an internal-combustion engine is almost an adiabatic process. The temperature rises as the air-fuel mixture in the cylinder is compressed. The expansion of the burned fuel during the power stroke is also nearly an adiabatic expansion with a drop in temperature.
 
3.Eudiometry involves combustion/ single or double replacement reaction. the device is a graduated cylinder, closed at the top end with the bottom end immersed in water or mercury. The liquid traps a sample of gas in the cylinder and the graduation allows measuring the volume of the gas. an electric spark can initiate reaction in the gas mixture and the graduation on the cylinder can be read to determine the change in volume resulting from the reaction.

Answered by  | 5th Oct, 2010, 11:45: PM

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