According to the following thermochemical reaction, how much energy is involved in the reaction of 18.5 g of NaHCO3? Is the reaction endothermic or exothermic according to how the thermochemical equation is written?
2NaHCO3(s) + 129 kJ → Na2CO3(s) + H2O(l) + CO2(g)
You have to add heat so endothermic
129 J per 2 mol
1 mol = 23 + 1 + 12 + 48 = 84 grams
2 mol = 168 grams
we only have 18.5 grams so
(18.5/168)129 = 14.2 Joules
I think Damon made a typo. That is kJ and not J.
Thanks for catching that !!!
To determine the energy involved in the reaction of 18.5 g of NaHCO3, we need to use the given thermochemical equation and perform a stoichiometric calculation.
Step 1: Calculate the molar mass of NaHCO3.
The molar mass of NaHCO3 can be calculated by summing up the atomic masses of its constituent elements. The atomic masses of Na, H, C, and O are 22.99 g/mol, 1.01 g/mol, 12.01 g/mol, and 16.00 g/mol, respectively.
Molar mass of NaHCO3:
= (22.99 g/mol) + (1.01 g/mol) + (12.01 g/mol) + (3 * 16.00 g/mol)
= 84.01 g/mol
Step 2: Determine the number of moles of NaHCO3.
To calculate the number of moles, we divide the given mass of NaHCO3 (18.5 g) by its molar mass (84.01 g/mol).
Number of moles of NaHCO3:
= 18.5 g / 84.01 g/mol
≈ 0.220 mol
Step 3: Calculate the energy involved in the reaction.
The thermochemical equation states that the reaction of 2 moles of NaHCO3 releases 129 kJ of energy. Therefore, we need to calculate the energy for 0.220 mol of NaHCO3.
Energy involved in the reaction:
= (129 kJ / 2 mol) * 0.220 mol
= 14.19 kJ
Therefore, the energy involved in the reaction of 18.5 g of NaHCO3 is approximately 14.19 kJ.
To determine if the reaction is endothermic or exothermic, we analyze the direction of the energy change in the thermochemical equation. In this case, the reaction is written as releasing 129 kJ, which means energy is being lost or given off. This is characteristic of an exothermic reaction, where energy is released to the surroundings.