Most Common Chemistry Final Exam Question: Limiting Reactants Review

This Chemistry review covers a common final exam question/ topic. We'll go over how to find the limiting reactant, excess reactant, theoretical yield, percent yield, actual yield and how to find the amount of excess left over.
📗 FREE CHEMISTRY SURVIVAL GUIDE
melissa.help/freechemguide
📘 FREE ORGANIC CHEMISTRY SURVIVAL GUIDE
melissa.help/freeochemguide
💯 HERE'S HOW TO PASS ORGANIC CHEMISTRY 🎉
chemmunity.info/youtube
👉 MORE CHEMISTRY RESOURCES I CREATED 👈
melissamaribel.com/
🎓 CHECKOUT MY COMPLETE CHEMISTRY GUIDES:
📕 Thermochemistry Guide
melissa.help/thermonotes
📗 Acids and Bases Guide
melissa.help/acidbase1notes
📘 Naming Compounds and Acids Guide
melissa.help/namingnotes
📙 Dimensional Analysis, Significant Figures, and Density Guide
melissa.help/sigfignotes
📕 Gas Laws Guide
melissa.help/gaslawsnotes
📗 Stoichiometry Guide
melissa.help/stoichnotes
📘 Redox Reactions Guide
melissa.help/redoxnotes
📙 Molarity Guide
melissa.help/molaritynotes
📕 Limiting Reactants Guide
melissa.help/limreactnotes
📗 Lewis Structures Guide
melissa.help/lewisnotes
📘 Kinetics Guide
melissa.help/kineticsnotes
📙 Titrations Guide
melissa.help/titrations
📕 Matter, Atomic Structure, Empirical and Molecular Formulas Guide
melissa.help/matterguide
🙌 This was my go-to homework help when I was in school. Chegg Study is one of my favorites.
melissa.help/cheggstudy
📚 I made the mistake of buying all of my textbooks, I wish I had the option of renting them. Thankfully you do, with Chegg Textbook Rentals.
melissa.help/cheggbooks
💁‍♀️ HI I'M MELISSA MARIBEL
I help students pass Chemistry and Organic Chemistry. I used to struggle with this subject, so when I finally graduated with a bachelor's degree in Chemistry, I became a tutor so that you wouldn't have to struggle like I did. I know that with the right help, YOU CAN LEARN ANYTHING!
DISCLAIMER: Some links in the description are affiliate links, which means that if you buy from those links, I’ll receive a small commission. This helps support the channel and allows me to continue making videos like this. Thanks for the support!

[@sanaajennings6285]

I haven't even finished chem 1 but I went from exam 1- 65% 2nd -80% to the 3rd 92% because of your videos ❤ as soon as I can i will be visiting your patreon

[@sanaajennings6285]

I'm going to bust my butt to do well on the final

[@spider-mancantsee5875]

What I should’ve done now I have a 59 and need to do well on the final so watching this and writing facts down to study till then

[@nonjabulomacu9277]

Amazing how your videos taught me all the chemistry I know and am loving the smile that stays on my face when I write chemistry exams/tests. THANK YOU!!!!!!!!!!

[@simranc7690]

My Chemistry 101 final is on Wednesday (it's Monday...) and I only had like three days to prepare for it so binging your youtube channel has been a bigger help than my own professor. I'm finally understanding all these concepts without spending like four hours on one topic! Thank you SO much for including practice problems you're the reason I might not fail.

[@melissamaribel]

You are so welcome!!

[@L0CV5T]

Exactly the same situation here, but today is the final, in 30min. Wooo i love chem…

[@zeldaloops6941]

Seriously thank you thank you! I appreciate your videos so much and the time that you put into it. You are really making a difference and I’m so glad I came across your channel! ❤️ please keep doing what you are doing, it is making a difference for sure!

[@kimmypaz2208]

I have a final today and this cleared SO MUCH for me omggg 😭 thank you Melissa! 💗

[@paoloalejandrino2523]

Still managed to get a C in my chem 1 final. I would've fluked the course if not for your videos! Will make a comeback on chem 2!!

[@btw3344]

Why take chem 2? Is it part of your major I thought you only need one science lab

[@MATTicall]

@@btw3344 must be premed

[@aidan2849]

@@btw3344 do biology majors need to take the ACS final for chem. Im in biology but still take chem courses and apparently we do. Can we opt out or something?

[@alexandrakwasnik5868]

I have a chemistry final exam tomorrow for Gen Chem 1. I didn't know stoichiometry or limiting reactant, however, from watching your videos, I not understand both! a MASSIVE thank you! I feel way more confident going into my exam and I am definitely going to keep watching your videos!

[@toastom]

How did it go?

[@adriennejengmanato2259]

Thank you for this Melissa!😍 I now slightly understand stoichiometry👏

[@jenny030916]

This is AMAZING! Thank you so much Melissa😊

[@ernestoyounes2946]

thank you mrs melissa, i hope i can boost my chem from 70% to 100% on the final exam and get over with it

[@heavenlyrelaxations101]

So helpful thank you for all that you do!

[@ansri24]

my finals are less than a week and ur videos are saving me, thanks a lot

[@briannamainolfi4704]

I have my gen chem 1 final tomorrow morning and your videos have been super helpful thank you!!! Update: I just took my final and this helped me so much!!

[@mimimo6223]

This really took a long time for me to understand the limiting reactants and finding each yield and excess reactants to percentages lol but thank you so much this really helped me greatly.

[@quinnobrien8602]

These videos are the best!

[@aquarxus4894]

Hi sorry this is unrelated but in regards to chemistry if we wanted to investigate the affect of concentration of rate reaction how will we do so with: HCL and Antacid in this case we have to do a prac where we need to put our results in a graph where we vary the concentrations of the HCL from 0.1 m 0.5 m 1m but maintain the antacid so far I have plotted just the times of when the reaction is done but I don’t know how to record the rest in order to make a graph?

[@jhanelljacks9932]

I’ve watched all most every video on youtube for this and still not completely understanding it THANK YOU my test is today hopefully I pass !!!!

[@rahulrathod170]

hope you're test went well. Writing mine tomorrow. All the best for the future

[@jacobseo3578]

OMG... Just OMG. She saved me from the Chem test. Thx!!!

[@trishaawate4030]

I LOVE YOU THANK YOU FOR SAVING ME IN CHEM!!!

[@medea4724]

love this channel

[@glompxme]

My professor hasn't taught a class since the pandemic, so you're saving me! I hope to at least get a C. She yeeted stuff from the hw so she wouldn't have to grade it but it'll be on the final.

[@namasteayla]

Thank you soooo much

[@michelleescalera485]

You’re amazing ! God Bless you!!!

[@melissamaribel]

Thanks Michelle 😊💕

[@mido92i19]

you're a teaching genius

[@melissamaribel]

Aw thanks!

[@theifking1]

How did you get 163g Fe2O3 for the used? I keep getting 653g

[@NadiaSambolin]

You are amazing!!!

[@jeanalik6978]

There is an easier way of working out the limiting reactant. Just find the moles of both reactants and use the molar ratio to compare both reactants. The reactant with fewer moles is gonna be your limiting reactant.

[@melissamaribel]

Yep that works too, I just like getting to the grams because most questions ask for the theoretical yield and students forget how to get there. So I like showing you one way that answers two questions.

[@jeanalik6978]

Melissa Maribel Ahh I understand. However wouldn’t finding the limiting reactant by moles be more effective as you exclude the other reactant for the second part of the question.

[@melissamaribel]

Both are effective, if you prefer stopping at moles then do that. The important part is that you understand how to get there 👍

[@mohammadschool1968]

how do you know what product to choose from if u have 2 of em

[@konstantinrebrov675]

Theoretical yield is the quantity of a product obtained from the complete conversion of the limiting reactant in a chemical reaction. It is the amount of product resulting from a perfect (theoretical) chemical reaction, and thus not the same as the amount you'll actually get from a reaction in the lab. Theoretical yield is commonly expressed in terms of grams or moles. In contrast to theoretical yield, the actual yield is the amount of product actually produced by a reaction. Actual yield is usually a smaller quantity because few chemical reactions proceed with 100% efficiency because of loss recovering the product and because other reactions may be occurring that reduce the product. Sometimes an actual yield is more than a theoretical yield, possibly because of a secondary reaction that yields additional product or because the recovered product contains impurities.

[@user-le3xf3hi6u]

What if it says mixed with ? the wording is tripping me up because I don't know if I have to add the two given numbers in grams and then set the problem up or am I still solving for one? In the reaction given below, 35.2 g of bromine (Br2) is MIXED with 23.1 g of phosphorus (P) to produce phosphorus tribromide (PBr3). What are the limiting reactant and the theoretical yield, in grams, of phosphorus tribromide?

[@4JUVIE]

This is the same as igcse cambridge right?

[@phoenixjohnson3149]

When I did this on my own for some reason my brain said find the molar mass of 2Fe because on the product side the coefficient was 2.. its like throwing me off a bit and i don't understand why

[@Chembynlsir]

Thanks mam

[@courtneyminnoe7619]

So if you start with finding Fe instead of CO2 the first time you would have to continue finding Fe in the second one?

[@nonjabulomacu9277]

So...is percentage yield accuracy, how close you were to achieving the perfect scenario or compound? Edit: Nevermind, asked too soon.

[@chandrapriyan5972]

I am so much inspired by you mam

[@melissamaribel]

Thank you!

[@Flaystray]

Knowing what percent yield actually is solidifed my faith in chemistry

[@WOG18]

Can you please explain how you got 116.8g

[@emily6869]

I am not sure why, but on the conversion os CO to Fe, why is the grams of Fe only 55.85g? In the reactants it is 2Fe, so why was the molar mass not done 2Fe, only 1Fe? Is it because that is just converting it back to grams? So the Fe is only one because that is the conversion done? The rest totally helped me. Before, I didn't even know where to start. This clarifies limiting reactant problems so much.

[@melissamaribel]

For molar mass it's only 1 mole of that element or that compound, so for Fe we are not looking at the mole to mole ratio or the balanced equation instead we only want 1 mole of Fe = molar mass of just 1 Fe.

[@emily6869]

@@melissamaribel Thanks!

[@juanmartin7902]

my final is tomorrow lol goodluck to all!

[@Lana-dn2kq]

Love and BigThankyou from India 🙌🙌

[@melissamaribel]

Thanks!

[@whowas1203]

OH my god i really thought i was going to wing it because i could not save my life doing these problems. I understand it a little bit more and i think I'm buying the notes chem 2 if i pass

[@kelvinksimwawa4138]

I have exams in August 😥😥😥i have never been so good in che 110 I really need ur help Madam and this videos is so helping

[@stellalee2946]

girl is so relatable

[@user-gw8qg7rm5i]

Amazing!

[@melissamaribel]

Thanks!

[@user-gw8qg7rm5i]

Can you please make videos on organic chemistry?

[@melissamaribel]

I'll get on that right away!...... Ok all done..... here's my second channel...kzbin.info/door/SzvQG5seY5dA59RIkZlicg 😂

[@sanaajennings6285]

@@melissamaribel 😭

[@lsnickysfiso4580]

Someone please help would appreciate If magnessium burns in the air to form magnessium oxide accordingly to the following balanced equation 2 Mg +O2->2Mg If the percentage yield of this reaction is only 80% calculate the mass of magnessium that needs to be burned to produce 30g of magnessium oxide

[@melissamaribel]

Hey there, did you still need help with this question?

[@lsnickysfiso4580]

@@melissamaribel yes please i would appreciate ♡

[@lsnickysfiso4580]

@@melissamaribel please

[@melissamaribel]

You are a given the percent yield of 80% and the actual yield of 30 g MgO 1)Start with finding the theoretical yield by plugging the percent yield and actual yield into the percent yield formula shown at 23:29. 2) After you found your theoretical yield of MgO you will work your way back to grams of Mg. So you'll go from grams of MgO to mol MgO to mol Mg to grams of Mg and you are done. Make sense?

[@lsnickysfiso4580]

@@melissamaribel thanks i truly understand 😄 thanks melissa you are a star 🙆🙌

[@gouravtagore17]

Love from India

[@tomthinyurembam8805]

Ma'am you are beautiful and intelligent...i learned something from you

[@user-lt6hz7jh2p]

Chemistry final manana al chingarle 🤘🏻👍

[@melissamaribel]

Órale!

[@lidiyabirabiro8210]

❤❤❤❤❤

[@thegamechanger7157]

Make damage

[@samramirez4244]

Girl I love you