Question

A mixture of gaseous reactants is put into a cylinder, where a chemical reaction turns then into gaseaous 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.

From previous experiments, this chemical reaction is known to release 173.kJ of energy.

the temperature of the water bath is monitored, and it is determined from this data that 37.2kJ of heat flows out of the system during the reaction.

Is the reaction exothermic or endothermic?

Does the temperature of the water bath go up or down?

Does the piston move in or out?

Does the gas mixture do work, or is work done on it?

How much work is done on (or by) the gas mixture? Round your answer to 3 significant digits.

Answer 1

Is the reaction exothermic or endothermic?

Since the reaction is known to release energy, this is exothermic reaction.

Does the temperature of the water bath go up or down?

Since the system losing heat and this heat is supplied to the water, the temperature of the water bath go up.

Does the piston move in or out?

The piston move out.

Does the gas mixture do work, or is work done on it?

The gaseous mixture do work.

How much work is done on (or by) the gas mixture? Round your answer to 3 significant digits

According first law of thermodynamics,

deltaU = q + w

Now,

since the system releases energy, deltaU = - 173. kJ

Since heat is lost by the system, q = - 37.2 kJ

Then work done, w = ?

Therefore using formula,

- 173. = - 37.2 + w

w = - 173. + 37.2

w = - 135.8

w = - 136. kJ

Since, w = negative, the work is done by the system.