Based on the balanced equation
2NBr3 + 3NaOH → N2 + 3NaBr + 3HOBr
calculate the number of of excess reagent units remaining when 116 NBr3 molecules and 180 NaOH formula units react?
I calculated the excess reagent to be NaOH. So is the units of remaining excess reagent 6 NaOH?
You are exactly right. Good work.
To determine the remaining units of excess reagent, you first need to calculate the number of moles for both NBr3 and NaOH based on the given quantities.
1. Start by converting the given quantities of NBr3 and NaOH to moles:
Given:
- NBr3: 116 molecules
- NaOH: 180 formula units
To convert to moles, use Avogadro's number (6.022 x 10^23 molecules or formula units/mol):
- Moles of NBr3 = 116 molecules / (6.022 x 10^23 molecules/mol)
- Moles of NaOH = 180 formula units / (6.022 x 10^23 formula units/mol)
2. Calculate the mole ratio between the reactants based on the balanced equation:
From the balanced equation: 2NBr3 + 3NaOH → N2 + 3NaBr + 3HOBr
The mole ratio between NBr3 and NaOH is 2:3.
3. Find the limiting reactant:
To determine the limiting reactant, compare the moles of NBr3 and NaOH using the mole ratio. The reactant with fewer moles is the limiting reactant.
- NBr3: moles calculated in step 1
- NaOH: moles calculated in step 1
Using the mole ratio 2:3:
- Calculate the expected moles of NBr3 based on the moles of NaOH: (3/2) * Moles of NaOH
- Compare the expected moles of NBr3 to the actual moles of NBr3. If the actual moles of NBr3 is smaller, it is the limiting reactant.
4. Calculate the excess reagent used:
Since NaOH is the excess reagent, we need to determine the moles of NaOH used in the reaction.
- The moles of NaOH used can be calculated based on the moles of limiting reactant (either NBr3 or NaOH) and the mole ratio from the balanced equation.
Using the mole ratio 2:3:
- Calculate the moles of NaOH used based on the moles of limiting reactant: (2/3) * Moles of limiting reactant
5. Calculate the remaining moles of excess reagent:
To find the remaining moles of NaOH, subtract the moles of NaOH used from the initial moles of NaOH.
6. Convert the remaining moles of NaOH to units:
Multiply the remaining moles of NaOH by Avogadro's number to convert to units (molecules or formula units).
The result will give you the number of excess reagent units remaining.
To determine the number of excess reagent units remaining, we first need to determine the limiting reagent. The limiting reagent is the reactant that is completely consumed in a chemical reaction, thus determining the maximum amount of product that can be formed.
In this case, you correctly identified NaOH as the excess reagent. To confirm this, we'll use stoichiometry to calculate the amount of product that can be formed from both reactants.
From the balanced equation, we can see that the stoichiometric ratio between NBr3 and NaOH is 2:3. This means that for every 2 molecules of NBr3, we need 3 molecules of NaOH to react completely.
Let's calculate the amount of NBr3 and NaOH needed based on the given quantities:
116 NBr3 molecules × (3 NaOH molecules / 2 NBr3 molecules) = 174 NaOH molecules
180 NaOH formula units remain unchanged since it is the excess reagent.
Since we have 180 NaOH formula units left and we started with 180 NaOH formula units, it means that all of the NaOH has been used in the reaction. Therefore, there are no remaining units of excess reagent.
In conclusion, the units of remaining excess reagent NaOH is 0, not 6 NaOH as you suggested.