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Ch. 8 Stoichiometry

TN Ch 8.1 Date

Title and

Highlight

Topic:

EQ:

Write Question out (left side of red line) and answer

it (Highlight answer) based on from what you read.

• Write out the notes from my website.

• You may use different color pens.

• Use Bullets or Number notes.

• Space out your notes so you can add any

additional into during lecture.

NO HIGHLIGTING, UNDERLINING, etc

WE WILL DO OUR FOCUS NOTES

TOGETHER

• Write 2-3 sentences (end of notes) from what

you learned from reading, notes, and/or lecture.

Right Side – NOTES ONLY

TN Ch 8.1

Title and

Highlight

DRAW ANY PICTURES, FIGURES,

AND WRITE OUT ANY PRACTICE

PROBLEMS/QUESTIONS.

WE WILL ANSWER THEM TOGETHER.

LEAVE SPACES SO WE CAN ANSWER

QUES.

LEFT Side – PICTURES, PRACTICE PROBLEMS, ETC

EQ: What is a mole ratio

and how is it used in

conversions?

Ch. 8.1-8.3

Topic: Stoichiometry

READ Ch 8.1-8.3 (pg. 249-253)

Write Questions & Answer Questions #1, 2a, 3

(notes side) Highlight answer

• Stoichiometry refers to the

numerical relationship between

chemical quantities in a

balanced chemical equation.

Interpreting Chemical Equations

The first thing that must be done is to ______________ the equation!

___N2 (g) + ___H2 (g) ___NH3 (g)

What are the “mole ratios” in this equation?

Here are the kinds of information you can get from the equation:

• ____ mole N2 + ____ moles H2 ____ moles NH3

• ____ molecules N2 + ____ molecules H2 ____ molecules NH3

3 2

balance

1 3 2

1

1 3 2

Avogadro’s

#

Stoichiometry Conversion Chart

Mole A

Mass A

Particles A

Volume A

Molar

Mass

Mole

Ratio

Avogadro’s

# Mole B

Mass B

Particles B

Volume B

Molar

Mass

Atoms/Ions in A

Count

them

Atoms/Ions in B

mole a mole b Molar

Volume

Molar

Volume

Volume

Ratio

Count

them

Count

them Count

them

Don’t draw – you already have a copy

Mole to Mole Conversions

• The conversion factor is the mole ratio.

• The mole ratio comes from the _________________ of the

balanced chemical equation.

Step 1: Write down the known (A) and unknown (B).

Step 2: Set up a mole ratio to change from moles A to moles B

coefficients

Practice Problems: N2 (g) + 3H2 (g) 2NH3 (g)

1) How many moles of ammonia can be made from 7 moles of nitrogen reacting

with an excess of hydrogen?

2) How many moles of hydrogen are required to completely react with 8 moles of

nitrogen to produce ammonia?

3) How many moles of hydrogen are needed to react with an excess of nitrogen to

make 10 moles of ammonia?

Left side - Leave about 5 spaces between each problem

EQ: How are mole ratios used in

mole-mass conversions?

Ch. 8.4

Topic: Mole to Mass

Conversion

READ Ch 8.4 (pg. 253-257)

Write Questions & Answer Questions #4


Practice Problem: CaH2 (s) + 2H2O (l) Ca(OH)2 (aq)+ 2H2 (g)

1. What mass of calcium hydroxide will be produced from the

reaction of 2.50 mol of calcium hydride with excess water?

(another product is hydrogen gas)

2. What mass of water is needed?


Mass-Mass Conversion Problems

Mass-Mass: (mass A to moles A to moles B to mass B)

Step 1: Write down the known (A) and unknown (B).

Step 2: Convert from mass A to moles A

Step 3: Convert from moles A to moles B using a mole ratio.

Step 4: Convert from moles B to mass B.

Practice Problem:

3. How many grams of ammonia can be made

from reacting 39.0 grams of nitrogen with an

excess of hydrogen?

• N2 (g) + 3H2 (g) 2NH3 (g)


EQ: What is the difference

between L.R. and E.R.?

Ch. 8.5

Topic: Limiting and

Excess Reactants

***BONUS QUESTION ON EXAM***

READ Ch 8.5 (pg. 257-260)

Write Questions & Answer Questions #7


• The limiting reagent is a REACTANT that

_________ _____ first.

• Once the limiting reagent runs out, the rxn

stops!!

• The reactant that is in abundance (reactant that

you have too much of) is called the ___________

reagent.

Limiting Reagent (or Limiting Reactant)

runs out

excess

To summarize:

• Limiting reactant (or limiting reagent)—the reactant that is completely consumed in a chemical reaction.

– You run out of this reactant first and it stops the rxn.

– Once you determine LR, that chemical starts every calculation especially THEORETICAL YIELD of product

• Excess Reactant— the reactant you have too much of and have leftovers not being used in the rxn.

Practice Problem #1

2Na(s) + Cl2(g) 2 NaCl(s)

Know: 53.2 g Na and 65.8 g Cl2

Find: limiting reactant & theoretical

yield of NaCl


Practice Problem #2

Cu2O(s) + C(s) 2 Cu(s) + CO(g)

Given: 11.5 g Cu2O and 114.5 g C

Find: limiting reactant & theoretical

yield of Cu


EQ: How do you calculate %

yield from actual and theoretical

yields?

Ch. 8.6

Topic: Percent Yield

READ Ch 8.6 (pg. 260-264)

Write Questions & Answer Questions #8 - 9


• Percent Yield is a ratio that tells us how ________________ a

chemical reaction is.

• The higher the % yield, the more efficient the reaction is.

(How good is your data!!)

Actual Yield

Theoretical Yield

• The ___________ yield is the amount you experimentally get

when you perform the reaction in a lab. (Your result)

• The _______________ yield is the amount you are ideally

supposed to get if everything goes perfectly. (No errors in lab -

what you should have got).

–You can calculate this amount using stoichiometry!

Percent Yield

x 100 % Yield =

efficient

actual

theoretical

Actual Yield and

Percent Yield

• The Percent yield is always less than

100%.

• Why???

– Errors happen.

– Some of the product does not form.

Practice Problem #1

USE INFO FROM CH 8.5 TN!!

a. Example: 2Na(s) + Cl2(g) 2 NaCl(s)

Given (grams): 53.2 g Na and 65.8 g Cl2

Find: limiting reactant and theoretical yield of

NaCl.

b. Given: actual yield 86.4 g NaCl (PRODUCT)

Find: percent yield


Practice Problem #1

USE INFO FROM CH 8.5 TN!!

a. Example 8.6: Cu2O(s) + C(s) 2 Cu(s) + CO(g)

Given (grams): 11.5 g Cu2O and 114.5 g C

Find: limiting reactant and theoretical yield of Cu

b. Given: actual yield 87.4 g Cu

Find: percent yield


ch. 8 stoichiometry - nrchemistry.weebly.com · tn ch 8.1 title and highlight draw any pictures,...

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