Determine how much heat (in kilojoules) is evolved or absorbed in the reaction of 1.05 g of Na with H2O:
2Na(s)+2H2O(l) →2NaOH(aq)+H2(g),ΔH∘=−368.4 kJ
heat=.368kJ/2moles * 1.05/23
Heat of reaction is not given per mole, it is given per 2 moles Na, or 2 moles water.
heat=.368kJ/2moles * 1.05/23
Heat of reaction is not given per mole, it is given per 2 moles Na, or 2 moles water.
The negative sign means heat is given off.
JOHY
To determine the amount of heat evolved or absorbed in a reaction, you need to use the concept of stoichiometry.
First, we need to determine the number of moles of sodium (Na) reacted. To do this, we divide the given mass of sodium (1.05 g) by its molar mass. The molar mass of sodium (Na) is approximately 22.99 g/mol.
Number of moles of Na = Mass of Na / Molar mass of Na
= 1.05 g / 22.99 g/mol
Next, we verify the stoichiometry of the reaction to determine the moles of heat evolved or absorbed. From the balanced chemical equation, we can see that 2 moles of Na reacts to produce -368.4 kJ of heat.
Based on the stoichiometry of the reaction, we can conclude that -368.4 kJ of heat is released per 2 moles of Na.
To find the heat evolved or absorbed for the given amount of sodium (1.05 g), we can use the following conversion:
Number of moles of Na => Moles of heat evolved or absorbed => Heat evolved or absorbed in kJ
Let's calculate all the steps:
1. Number of moles of Na:
Number of moles of Na = 1.05 g / 22.99 g/mol
2. Moles of heat evolved or absorbed:
From the stoichiometry of the balanced equation, we know that 2 moles of Na produce -368.4 kJ of heat.
Moles of heat evolved or absorbed = (Number of moles of Na / 2) * -368.4 kJ
3. Heat evolved or absorbed in kJ:
Heat evolved or absorbed in kJ = Moles of heat evolved or absorbed
Now, let's plug in the values and calculate the heat evolved or absorbed:
Number of moles of Na = 1.05 g / 22.99 g/mol = 0.0456 mol
Moles of heat evolved or absorbed = (0.0456 mol / 2) * -368.4 kJ = -8.41344 kJ
Therefore, the amount of heat evolved or absorbed in the reaction of 1.05 g of Na with H2O is approximately -8.41344 kJ. Note that the negative sign indicates heat is released in the reaction.