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### Finding the limiting reaction

Posted: Sun Oct 06, 2019 2:21 pm
When finding the limiting reaction, where does the molar ratio come into play? Limiting reactants are a topic I’m struggling to grasp. Is there a ste by step way to go about solving the problems?

### Re: Finding the limiting reaction

Posted: Sun Oct 06, 2019 2:24 pm
The molar ratio is always important. When you figure out the number of moles you have of each substance, you then use the molar ration to find the actual amount of each substance you need for each amount of yield.

### Re: Finding the limiting reaction

Posted: Sun Oct 06, 2019 2:32 pm
This is the way I do it:

1. First find the moles of each reactant by dividing the grams of the reactant by its molar mass.

2. Use the moles of each reactant to calculate how much product can be produced (it doesn't matter which product you chose as long as you keep it consistent for all of the reactant calculations). To do this you multiply the moles of reactant by the ratio of moles reactant to moles product. So, for example, if you have 2 moles of reactant and for every 1 mole of this reactant you make 2 moles of product, then you would multiply 2 by 2 and you get 4 moles of product. Here is a diagram of this reaction:

1R ---> 2P

3. Compare all of the moles of product that you get and the reactant that produces the least moles of product is the limiting reactant.

Hope this helps.

### Re: Finding the limiting reaction

Posted: Sun Oct 06, 2019 6:29 pm
Some steps I wrote down:
- write the balanced equation
- calculate the molar mass of each reactant and product
- convert the known masses of the reactant and product to moles
- compare calculated moles to required moles to determine if there is a limiting reactant
The limiting reactant is going to be the reactant that has the smallest number of moles that you calculated.