Thermodynamics problem! Please help!

Question

A student takes a Styrofoam cooler in fills it with 2.00 L of water. He then adds a small amount of sodium to it and it reacts according to the equation below. The initial temperature of the water is room temperature, 23.9°C, and the temperature of the water after the reaction is complete is 25.8°C. The reaction takes place at 0.987 atm pressure and produces 1.968 L of hydrogen gas.

2Na(s) + 2 H2O(l) -> 2Na(aq) + H2(g)

 * assume all the heat is tranfered to water and the resulting solution has the same density/specific heat/ total mass as the water alone *

1. Determine the amount of heat absorbed or released by the reaction.
2. Calculate the work for this reaction.

3.determine the number of grams of sodium that were added to the cooler of water.

 

Answer 1

Please see my previous answer to this question before including part 3.

 

3.  determine the number of grams of sodium that were added to the cooler of water.

PV = nRT and solve for n, moles of H2 gas

n = PV/RT = (0.987 atm)(2.00 L)/(0.0821 L-atm/K-mol)(296.9 K)

n = 0.08098 moles H2 gas

moles Na(s) used = 0.08098 moles H2 x 2 moles Na/mole H2 = 0.1620 moles Na(s)

mass of Na(s) = 0.1620 moles Na x 22.99 g/mole = 3.72 g Na(s)