How much heat is absorbed/released when 20.00 g of NH2 reacts in the presence of excess O2 to produce NO and H2O according to the following chemical equation:
4NH3 + 5O2 --> 4NO + 6H2O, deltaH= +1168 kJ.
The answer is 342.9 kJ of heat absorbed. I want to know how to complete this problem.
I figured it out, deltaH is in kJ/grams which is 68. So 20.0gx(1168kJ/68g)=342.9 kJ.
Yes, or you could have converted 20g to mols which is 20/17 = 1.176, then
1168 kJ/4mol = 292 kJ. Then 292 x 1.176 = 343 kJ
To determine the amount of heat absorbed or released in the given reaction, you need to use stoichiometry and the given molar enthalpy change.
Given:
Mass of NH3 = 20.00 g
Reaction: 4NH3 + 5O2 -> 4NO + 6H2O
Delta H = +1168 kJ
1. Calculate the number of moles of NH3:
Molar mass of NH3 = 17.03 g/mol
Number of moles of NH3 = mass / molar mass = 20.00 g / 17.03 g/mol = 1.175 mol
2. Use the stoichiometry of the reaction to find the amount of heat absorbed or released:
From the balanced equation, we can see that 4 moles of NH3 produce 1168 kJ of heat.
So, 1 mole of NH3 will produce 1168 kJ / 4 mol = 292 kJ of heat.
3. Calculate the heat absorbed or released for 1.175 moles of NH3:
Heat absorbed/released = 1.175 mol × 292 kJ/mol = 342.9 kJ
Therefore, the heat absorbed during the given reaction is 342.9 kJ.
To calculate the heat absorbed or released in a chemical reaction, you need to use the concept of stoichiometry. This concept allows us to relate the amounts of reactants and products in a balanced chemical equation. Here's how you can solve this problem step-by-step:
1. Write down the balanced chemical equation:
4NH3 + 5O2 --> 4NO + 6H2O
2. Calculate the molar mass of NH3 (ammonia). Nitrogen (N) has a molar mass of 14.01 g/mol, and hydrogen (H) has a molar mass of 1.01 g/mol. Multiply the molar mass of nitrogen by the number of nitrogen atoms present in NH3 (1 atom), and multiply the molar mass of hydrogen by the number of hydrogen atoms present in NH3 (3 atoms). Then add the two results to obtain the molar mass of NH3.
Molar mass of NH3 = (14.01 g/mol x 1) + (1.01 g/mol x 3) = 17.03 g/mol
3. Determine the number of moles of NH3. Divide the given mass of NH3 (20.00 g) by its molar mass (17.03 g/mol).
Number of moles of NH3 = 20.00 g / 17.03 g/mol = 1.174 mol (rounded to three decimal places)
4. Use the stoichiometry of the balanced equation to relate the number of moles of NH3 to the number of moles of NO. From the balanced equation, you can see that the stoichiometric ratio is 4:4 between NH3 and NO.
Number of moles of NO = (1.174 mol NH3 x 4 mol NO) / 4 mol NH3 = 1.174 mol
5. Calculate the heat absorbed using the given value of ΔH (enthalpy change) and the number of moles of NO. The ΔH value in the balanced equation is +1168 kJ for the reaction to produce 4 mol of NO.
Heat absorbed = (ΔH x Number of moles of NO) / Number of moles of 4 mol NO
Heat absorbed = (1168 kJ x 1.174 mol) / 4 mol NO = 342.9 kJ (rounded to one decimal place)
Therefore, the heat absorbed in this reaction is 342.9 kJ.