What mass of ammonia is necessary to produce 500 kJ of heat?
4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) ΔrH = -906 kJ mol-1
Well, the equation tells us that 4 moles of NH3 produces -906 kJ of heat. So let's start by finding out how many moles of NH3 we need to produce 500 kJ of heat.
If 4 moles of NH3 produce -906 kJ of heat, then 1 mole of NH3 would produce -906/4 kJ of heat.
Let's calculate this: -906/4 kJ = -226.5 kJ
So, 1 mole of NH3 produces -226.5 kJ of heat.
Now, let's find out how many moles of NH3 we need to produce 500 kJ of heat.
500 kJ / -226.5 kJ/mol = -2.21 mol
Oops! It seems like I made a mistake. Negative moles don't exist in chemistry, and I don't want to break any laws (except maybe the law of gravity). But since we're talking about the heat of reaction here, it's always positive. So, let's forget about the negative sign.
So, to produce 500 kJ of heat, we'll need approximately 2.21 moles of NH3.
But I'm not done yet! We still need to find the mass of NH3. And for that, we need the molar mass of NH3. The molar mass of NH3 is approximately 17.03 g/mol.
So, 2.21 moles of NH3 multiplied by 17.03 g/mol gives us approximately 37.66 grams of ammonia.
So, you'll need around 37.66 grams of ammonia to produce 500 kJ of heat. That should heat things up a bit!
To determine the mass of ammonia (NH3) necessary to produce 500 kJ of heat, we need to use the stoichiometry of the reaction and the molar enthalpy change (ΔrH) given.
The balanced equation tells us that 4 moles of NH3 produce -906 kJ of heat. The negative sign indicates that the reaction is exothermic.
First, we need to convert the given quantity of heat (500 kJ) to moles by dividing it by the molar enthalpy change:
500 kJ / -906 kJ/mol = -0.552 mol
The negative value simply indicates the direction of heat release in the reaction.
Now, we can use the stoichiometry of the balanced equation to determine the mass of NH3:
4 moles of NH3 produce -0.552 mol (According to stoichiometry)
x moles of NH3 produce 1 mole (unitary method)
x = (1 mol NH3 / 4 mol NH3) * -0.552 mol NH3
x = -0.138 mol NH3
To convert moles of NH3 to mass, we need to multiply by the molar mass of NH3, which is approximately 17.03 g/mol.
Mass of NH3 = -0.138 mol * 17.03 g/mol ≈ -2.35 g
Since mass cannot be negative, this indicates that there is no ammonia required to produce 500 kJ of heat in this reaction. It suggests that ammonia is likely a product or a reactant in the reverse reaction, or the given quantity of heat may be insufficient to produce any NH3.
To determine the mass of ammonia required to produce 500 kJ of heat, you need to use the balanced equation and the molar enthalpy change (ΔrH) provided.
Step 1: Calculate the moles of heat produced
Since the enthalpy change is given per mole of reaction, you need to convert the given value of 500 kJ into moles of heat. To do this, divide the given value by ΔrH:
Moles of heat = 500 kJ / -906 kJ/mol
Step 2: Use the stoichiometry of the balanced equation
Now that you have calculated the moles of heat, you can use the balanced equation to determine the moles of ammonia required. According to the balanced equation,
4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)
the coefficient of NH3 is 4. Therefore, for every 4 moles of NH3, 500 kJ of heat is produced.
Step 3: Calculate the mass of ammonia
Next, you need to convert the moles of ammonia into grams using the molar mass of ammonia (NH3). The molar mass of ammonia is:
Molar mass of NH3 = (1 x 14.01 g/mol) + (3 x 1.01 g/mol)
= 17.03 g/mol
Now, multiply the moles of ammonia by the molar mass to obtain the mass of ammonia required:
Mass of ammonia = Moles of ammonia × Molar mass of NH3
Remember, we previously found that for every 4 moles of NH3, 500 kJ of heat is produced.
Finally, compute the mass of ammonia:
Mass of ammonia = (Moles of heat × Molar mass of NH3) / 4
Substitute the values into the equation to find the mass.
If this is REALLY 906 kJ/MOLE that is 906 kJ/17 g NH3.
Then 17 x (500/906) = ? g NH3 required.