# How To Find The Amount of Excess Reactant That Is Left Over - Chemistry | Summary and Q&A

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August 11, 2017
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The Organic Chemistry Tutor
How To Find The Amount of Excess Reactant That Is Left Over - Chemistry

## TL;DR

Learn how to identify the limiting reactant, calculate grams of excess reactant consumed, and find the mass of excess reactant after the reaction is complete.

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### Q: How can I identify the limiting reactant in a chemical reaction?

To identify the limiting reactant, calculate the moles of each reactant by dividing the mass by their respective molar mass. Then, compare the mole-to-coefficient ratios of the reactants. The reactant with the lowest ratio is the limiting reactant.

### Q: How do I calculate the grams of excess reactant consumed?

Start with the mass of the limiting reactant and convert it to moles using its molar mass. Then, use the molar ratio between the limiting reactant and the excess reactant to convert moles of the limiting reactant to grams of the excess reactant.

### Q: How do I find the mass of the excess reactant remaining after the reaction?

Subtract the grams of excess reactant consumed from the initial mass of the excess reactant. The difference will give you the mass of the excess reactant remaining after the reaction is complete.

### Q: What is the chemical formula and balanced equation for the reaction between aluminum and sulfuric acid?

The chemical formula is Al2(SO4)3 and the balanced equation is 2Al + 3H2SO4 -> Al2(SO4)3 + 3H2.

## Summary & Key Takeaways

• The video explains a three-step process to find the mass of the excess reactant in a chemical reaction: identify the limiting reactant, calculate grams of excess reactant consumed, and find the remaining mass of excess reactant.

• The video provides an example using the reaction between aluminum and sulfuric acid to produce aluminum sulfate.

• The video also presents another example involving aluminum and elemental sulfur to produce aluminum sulfide.