To get the amount of excess reagent left over you must take the
[ Select ]
moles excess reactant you started with
moles excess reactant you used up
moles limiting reactant you started with
and subtract
[ Select ]
moles of excess reagent you used
moles of limiting reagent you used
moles of product you made
.

Question

To get the amount of excess reagent left over you must take the 
[ Select ]
moles excess reactant you started with
moles excess reactant you used up
moles limiting reactant you started with
 and subtract 
[ Select ]
moles of excess reagent you used
moles of limiting reagent you used
moles of product you made
 .

BlackTom AI · Accepted Answer

The question is asking how to determine the amount of excess reagent left after a reaction, and it uses two blanks that are filled from dropdown choices.
First, identify the intended process: to find the remaining amount of the excess reagent, you compare what you started with to what has been consumed of that same reagent in the reaction.
For the first blank, the correct choice is: moles excess reactant you started with. This represents the initial amount of the reagent that is in excess relative to the limiting reagent.
For the second blank, the correct choice is: moles of excess reagent you used. This is the amount of the excess reagent that actually reacted with the limiting reagent to form products (i.e., the portion of the excess that was consumed).
Putting these together, the calculation is: excess leftover = (moles excess reactant you started with) − (moles of excess reagent you used). This difference gives the moles of the excess reagent that remain unreacted after the reaction.
If we had other possible options (for example, references to moles of limiting reagent you started with, or moles of product made), those would not correctly describe the leftover amount of the excess reagent, because:
- Using moles limiting reagent you started with would mix up the concept of which reagent limits the reaction, and wouldn’t quantify unused excess directly.
- Using moles of product made would not reflect how much of the excess reagent was consumed versus remaining, since product formation depends on stoichiometry but doesn’t directly tell leftover quantities of reagents without additional steps.
- Any option referencing subtracting from the wrong quantity would lead to incorrect results, as the arithmetic must compare starting excess to how much of that excess was consumed.
In short, you take the initial amount of the excess reactant, subtract how much of that same reagent was actually used, and the result is the moles of excess reagent that remain unreacted in the mixture.

类似问题

Which species is the limiting reagent for the synthesis of urea: 2NH3 + CO2 → (NH2)2CO + H2O given 7.481 g of NH3 and 9.792 g CO2.

What amount of Al2O3 is produced from the reaction of 3.0 mol Al with 2.0 mol Fe2O3? 2Al + Fe2O3 è Al2O3 + 2Fe

The limiting reagent for a given reaction can be recognized because it is the reagent that

To get the amount of excess reagent left over you must take the moles excess reactant you started with and subtract moles of excess reagent you used .

The limiting reagent is not always the lowest number of moles present at the start of the reaction. It is the reactant that causes the least amount of product to be made.

If a reaction goes to completion how much of the limiting reagent will there be left?

What is the limiting reagent in each run? Read the introductory materials carefully!

Based on the balanced equation, 4P4 + 5S8 → 4P4S10 calculate the moles of excess reactant that are left over when 0.420 mol of P4 molecules and 0.737 mol of S8 molecules react?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单