Limiting Reactant Calculations Module #22

[Racquel Fox 2I]

According to the following equation, 0.750 g of C6H9Cl3 is mixed with 1.000 kg of AgNO3 in a flask of water. A white solid, AgCl, completely precipitates out. What is the mass of AgCl produced?
C6H9Cl3 + 3AgNO3 ---> AgCl + C6H9(NO3)3.
Molar Mass: C6H9Cl3 (187.50 g/mol), 3AgNO3 (169.88 g/mol), AgCl (143.32 g/mol)

The way I address this problem was by finding out which reactant was the limiting reactant. I found that C6H9Cl3 was the limiting reactant with 0.004 mol. I thought that would mean that the moles of AgCl would also be 0.004, and that I could convert that to grams, but that number didn't come up as any of the options on the module. What am I doing wrong?

[Andrew Jubintoro 3J]

Your chemical equation is not balanced.
It should be:
C6H9Cl3 + 3AgNO3 ---> 3AgCl + C6H9(NO3)3.

[Selena Quispe 2I]

Hi! So first step would be to balance your reaction! So you would put a three in front of AgCl. You identified that C6H9Cl3 was the limiting reactant so then you would multiply 0.004 mol times the moles of AgCl in the reaction which is three and then multiply by AgCl's molar mass which is 143.32g/mol. Your answer should be 1.72gAgCl. I hope this helps!

[Shivani Sakthi 1l]

Hello! The definition of a limiting reactant is the reactant that is completely used up in a reaction, therefore the formation of product would halt. For example if you have 16 wheels to put on a car but only 3 doors, the limiting reactant would be doors because the 4th car would have wheels but would lack a door. Therefore, you can see that the limiting reactant dictates the amount of product formed. So, in order to find the of AgCl, a product, the limiting reactant must be determined first.

Step 1: Balance the Chemical equation. This step is pivotal because the actual mole amount of the the reactants will be compared to the molar ratio, which will only be accurate if the equation is balanced.

Lets balance: C6H9Cl3 + 3AgNO3 ---> AgCl + C6H9(NO3)3 . With the law of conservation of mass, the equation should be C6H9Cl3 + 3AgNO3 ---> 3AgCl + C6H9(NO3)3 .

Step 2: find the molar mass of each reactant. In this case, C6H9C13= 187.50 g/mol, 3AgNO= 169.88 g/mol, AgCl- 143.32g/mol .

Step 3: divide the given masses by the molar mass. So .750 g/187.50 g C6H9C13= .004 g mol C6H9C13 . 1000 g AgNO3/ 169.88g = 5.89 mol AgNO3 .

Step 4: Look at the mole ratio in the balanced equation. It is 1 mole C6H9C13: 3 mole AgNO3. So, using our measurements, we delineate that 1 mole of C6H9C13 requires .012 moles of AgNO3. We have 5.89 moles of AgNO3 available, so, the other reactant, C6H9C13 is the limiting reactant.

Step 5: Knowing that C6H9C13 is the limiting reactant, we can use molar ratios to convert it into the the amount of AgCl.

.004 mol C6H9C13 x (3 mol AgCl/ I mol C6H9C13) x (143.32 g AgCl)= 1.72 g AgCl .