Question

1 atm pressure A mixture of gaseous reactants is put into a cylinder, where a chemical reaction turns them into gaseous products. The cylinder has a piston that moves in or out, as necessary, to keep a constant pressure on the mixture of 1 atm. The cylinder is also submerged in a large insulated water bath. (See sketch at right.) piston cylinder From previous experiments, this chemical reaction is known to absorb 236. kJ of energy. water bath gases The temperature of the water bath is monitored, and it is determined from this data that 341. kJ of heat flows out of the system during the reaction. exothermic Is the reaction exothermic or endothermic? endothermic x 6 ? up Does the temperature of the water bath go up or down down? Oneither in Does the piston move in or out? out neither does work Does the gas mixture do work, or is work done on it? work is done on it neither How much work is done on (ar by) the gas mixture? Round your answer to 3 significant digits. -577. kJ

Answer 1

Solution:

Part A) Exothermic

Because heat is evolved during process.

Part B) Up

In the given process, the heat absorbed by the water and therefore temperature rises.

Part C) In

Because the process releases heat, therefore it causes compression. Hence, volume decreases.

Part D) Work is done on it

In compression process, work is done by surrounding on system.

Part E) 105 kJ

Calculation:

Process is compression, hence W must be positive.

Q = ΔE + W

341 kJ = 236 kJ + W

W = 341 - 236 = 105 kJ