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2H2 + O2 → 2H2O 4H2 + 3O2 → CH4 + 2O2 → CO2 + 2H2O ..., Exams of Organic Chemistry

CH4 + 2O2. → CO2 + 2H2O. Try This: Circle the one that we would use up first (limiting reactant)? How many water molecules can we.

Typology: Exams

2021/2022

Uploaded on 09/12/2022

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Name ______________________________________________________ Date ________________ Period ________
Limiting Reactants/Reagents and Percent Yield of a Chemical Reaction
https://www.youtube.com/watch?v=LicEaaXhlEY
I. Limiting Reactant
Example 1: Nestles Chocolate Chip Cookies (recipe given)
Recipe calls for 2 eggs, but I only have _____________ . This will limit the number of cookies that I can make.
In this example, the limiting reactant is _____________ .
In a balanced Chemical Equation, the numbers in front of the reactants and products are called the ________________ .
Think of these numbers as the amounts, like in our recipe example.
Example 2: Hydrogen Combustion (main rocket chamber in the space shuttle)
2H2 + O2 2H2O
Try This: Circle the one that we would use up first (limiting reactant)? How many water molecules can we
make? _________ Leftovers? ____________
4H2 + 3O2
REACTANTS PRODUCT
Example 3: Combustion of methane (how a Bunsen burner works)
CH4 + 2O2 CO2 + 2H2O
Try This: Circle the one that we would use up first (limiting reactant)? How many water molecules can we
make? _________ How many carbon dioxide molecules? ___________ Leftovers? ____________
CH4 + 4O2
REACTANTS PRODUCTS
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Name ______________________________________________________ Date ________________ Period ________

Limiting Reactants/Reagents and Percent Yield of a Chemical Reaction

https://www.youtube.com/watch?v=LicEaaXhlEY

I. Limiting Reactant

Example 1 : Nestle’s Chocolate Chip Cookies (recipe given)

Recipe calls for 2 eggs, but I only have _____________. This will limit the number of cookies that I can make.

In this example, the limiting reactant is _____________.

In a balanced Chemical Equation, the numbers in front of the reactants and products are called the ________________.

Think of these numbers as the amounts, like in our recipe example.

Example 2 : Hydrogen Combustion (main rocket chamber in the space shuttle)

2H 2 + O 2 → 2H 2 O

Try This : Circle the one that we would use up first (limiting reactant)? How many water molecules can we make? _________ Leftovers? ____________

4H 2 + 3O 2 →

REACTANTS PRODUCT

Example 3 : Combustion of methane (how a Bunsen burner works)

CH 4 + 2O 2 → CO 2 + 2H 2 O

Try This : Circle the one that we would use up first (limiting reactant)? How many water molecules can we make? _________ How many carbon dioxide molecules? ___________ Leftovers? ____________

CH 4 + 4O 2 →

REACTANTS PRODUCTS

Since atoms aren’t actually big enough to see in the lab, we have to use our friend, the __________________.

Example 4 : Combustion of methane (how a Bunsen burner works)

CH 4 + 2O 2 → CO 2 + 2H 2 O

10 grams 10 grams

How many grams of CO 2 can we make with 10 grams of CH 4?

How many grams of CO 2 can we make with 10 grams of O 2?

Circle the one that we would use up first (limiting reactant)? What’s the most CO 2 we can make? _____________ grams; What product will have leftovers? ____________

II. Percent Yield

In the theoretical experiment above, we’re going to get _______ grams of CO2.

In reality, all of the molecules of the limiting reagent aren’t going to react – some will escape, etc. And so lots of times

your actual yield will be much _______ than your predicted (theoretical) yield.

Example 5 : Calculate the percent yield for Example 4 if the actual yield was 6.19 grams CO 2.

Theoretical Yield is always based on the _________________ Reagent, which is ___________________.

We are beginning our calculation of question (b) with our value calculated above from 32 g oxygen, which was

___________ mol O 2 , because it is what we will run out of first when running this reaction.

(b) C 3 H 8 + 5O 2 → 3CO 2 + 4H 2 O

(↑excess) 1 mol? grams

(↓from coeff. in bal. chem. eq.) (↓From periodic table)

________ mol O 2 (----------------------------------- )(----------------------------------- ) = __________ g H 2 O

(c) % yield = actual yield x 100 = ___________________ x 100 = _____________________ %

theoretical yield

Limiting Reagents, Theoretical Yield, and Percent Yield

https://www.youtube.com/watch?v=P2TKgSiPj1U

IMPORTANT 1ST^ STEP: Must have a correctly BALANCED EQUATION.

2Ca(s) + O2(g) → 2CaO(s)

9.0 grams 4.1 grams? grams

(a) Circle the limiting agent.

(b) What is the theoretical yield of calcium oxide? __________________________________

(c) What is the percent yield of calcium oxide if 9.5 g CaO were produced (given 9.0 g Ca and 4.1 g O 2 )? ___________%

(a)

(b) =

(c)