How much did our sodium-in-water demonstration raise the temperature of water in

ID: 942499 • Letter: H

Question

How much did our sodium-in-water demonstration raise the temperature of water in the dessicator jar? The reaction we performed was:

Assuming the dessicator jar is well insulated (like our coffee-cup calorimeter), the energy balance is:

The data from the demonstration was: (a) 1.0 kg water, (b) 22.0oC, (d) Cwater = 4.18 J/g-K, (e) mNa = 0.21 g

What is the molar mass of sodium, Na, in g/mol?

How many moles of sodium were added to the water (in moles)?

What was the change in energy, in joules, when the reaction occurred with the given amounts?

What was the mass of water in the jar in grams?

What is Tfinal in centigrade?

Molar mass of sodium = 23 g/mol

0.21 g of Sodium * (1 mol / 23 g) = 0.00913 moles of Sodium

deltaHrxn = 0.00913 moles * -184 kJ/mol = -1.68 kJ = -1680 J

Mass of water in grams = 1000 g

deltaT = 1680 J / (1000g * 4.18 J/gK)

deltaT = 0.4019 K = Tf - To = Tf - 295.15 K

Tf = 295.5519 - 273.15 = 22.4019

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