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Key concepts and summary

When reactions are carried out using less-than-stoichiometric quantities of reactants, the amount of product generated will be determined by the limiting reactant. The amount of product generated by a chemical reaction is its actual yield. This yield is often less than the amount of product predicted by the stoichiometry of the balanced chemical equation representing the reaction (its theoretical yield). The extent to which a reaction generates the theoretical amount of product is expressed as its percent yield.

Key equations

  • percent yield = ( actual yield theoretical yield ) × 100

Chemistry end of chapter exercises

The following quantities are placed in a container: 1.5 × 10 24 atoms of hydrogen, 1.0 mol of sulfur, and 88.0 g of diatomic oxygen.

(a) What is the total mass in grams for the collection of all three elements?

(b) What is the total number of moles of atoms for the three elements?

(c) If the mixture of the three elements formed a compound with molecules that contain two hydrogen atoms, one sulfur atom, and four oxygen atoms, which substance is consumed first?

(d) How many atoms of each remaining element would remain unreacted in the change described in (c)?

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What is the limiting reactant in a reaction that produces sodium chloride from 8 g of sodium and 8 g of diatomic chlorine?

The limiting reactant is Cl2.

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Which of the postulates of Dalton's atomic theory explains why we can calculate a theoretical yield for a chemical reaction?

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A student isolated 25 g of a compound following a procedure that would theoretically yield 81 g. What was his percent yield?

Percent yield = 31%

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A sample of 0.53 g of carbon dioxide was obtained by heating 1.31 g of calcium carbonate. What is the percent yield for this reaction?

CaCO 3 ( s ) CaO ( s ) + CO 2 ( s )

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Freon-12, CCl 2 F 2 , is prepared from CCl 4 by reaction with HF. The other product of this reaction is HCl. Outline the steps needed to determine the percent yield of a reaction that produces 12.5 g of CCl 2 F 2 from 32.9 g of CCl 4 . Freon-12 has been banned and is no longer used as a refrigerant because it catalyzes the decomposition of ozone and has a very long lifetime in the atmosphere. Determine the percent yield.

g CCl 4 mol CCl 4 mol CCl 2 F 2 g CCl 2 F 2 , percent yield = 48.3%

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Citric acid, C 6 H 8 O 7 , a component of jams, jellies, and fruity soft drinks, is prepared industrially via fermentation of sucrose by the mold Aspergillus niger . The equation representing this reaction is
C 12 H 22 O 11 + H 2 O + 3 O 2 2 C 6 H 8 O 7 + 4 H 2 O

What mass of citric acid is produced from exactly 1 metric ton (1.000 × 10 3 kg) of sucrose if the yield is 92.30%?

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Toluene, C 6 H 5 CH 3 , is oxidized by air under carefully controlled conditions to benzoic acid, C 6 H 5 CO 2 H, which is used to prepare the food preservative sodium benzoate, C 6 H 5 CO 2 Na. What is the percent yield of a reaction that converts 1.000 kg of toluene to 1.21 kg of benzoic acid?

2 C 6 H 5 CH 3 + 3 O 2 2 C 6 H 5 CO 2 H + 2 H 2 O

percent yield = 91.3%

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In a laboratory experiment, the reaction of 3.0 mol of H 2 with 2.0 mol of I 2 produced 1.0 mol of HI. Determine the theoretical yield in grams and the percent yield for this reaction.

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Outline the steps needed to solve the following problem, then do the calculations. Ether, (C 2 H 5 ) 2 O, which was originally used as an anesthetic but has been replaced by safer and more effective medications, is prepared by the reaction of ethanol with sulfuric acid.

2C 2 H 5 OH + H 2 SO 4 ⟶ (C 2 H 5 ) 2 + H 2 SO 4 ·H 2 O

What is the percent yield of ether if 1.17 L (d = 0.7134 g/mL) is isolated from the reaction of 1.500 L of C 2 H 5 OH
(d = 0.7894 g/mL)?

Convert mass of ethanol to moles of ethanol; relate the moles of ethanol to the moles of ether produced using the stoichiometry of the balanced equation. Convert moles of ether to grams; divide the actual grams of ether (determined through the density) by the theoretical mass to determine the percent yield; 87.6%

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Outline the steps needed to determine the limiting reactant when 30.0 g of propane, C 3 H 8 , is burned with 75.0 g of oxygen.

Determine the limiting reactant.

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Outline the steps needed to determine the limiting reactant when 0.50 mol of Cr and 0.75 mol of H 3 PO 4 react according to the following chemical equation.
2 Cr + 2 H 3 PO 4 2 CrPO 4 + 3 H 2

Determine the limiting reactant.

The conversion needed is mol Cr mol H 3 PO 4 . Then compare the amount of Cr to the amount of acid present. Cr is the limiting reactant.

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What is the limiting reactant when 1.50 g of lithium and 1.50 g of nitrogen combine to form lithium nitride, a component of advanced batteries, according to the following unbalanced equation?
Li + N 2 Li 3 N

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Uranium can be isolated from its ores by dissolving it as UO 2 (NO 3 ) 2 , then separating it as solid UO 2 (C 2 O 4 )·3H 2 O. Addition of 0.4031 g of sodium oxalate, Na 2 C 2 O 4 , to a solution containing 1.481 g of uranyl nitrate, UO 2 (NO 3 ) 2 , yields 1.073 g of solid UO 2 (C 2 O 4 )·3H 2 O.

Na 2 C 2 O 4 + UO 2 (NO 3 ) 2 + 3H 2 O ⟶ UO 2 (C 2 O 4 )·3H 2 O + 2NaNO 3

Determine the limiting reactant and the percent yield of this reaction.

Na 2 C 2 O 4 is the limiting reactant. percent yield = 86.6%

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How many molecules of C 2 H 4 Cl 2 can be prepared from 15 C 2 H 4 molecules and 8 Cl 2 molecules?

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How many molecules of the sweetener saccharin can be prepared from 30 C atoms, 25 H atoms, 12 O atoms, 8 S atoms, and 14 N atoms?

A structural formula is shown. A hexagonal ring of 6 C atoms with alternating double bonds has single H atoms bonded to four consecutive C atoms on the left side of the ring. The two C atoms on the right side of the ring, which are joined by a double bond, are also included in a 5 atom ring to their right. The C atom of this pair that is nearest the top of the structure is singly bonded to a C atom at the top of the 5 atom ring which has an O atom double bonded above. An N atom is singly bonded to the lower right of this same C atom. The N atom has an H atom bonded to its right and to its lower left, it is bonded to an S atom. The S atom is connected to the second C atom that is shared in the two rings. The S atom is also double bonded to an O atom to its lower right and is double bonded to a second O atom directly below it.

Only four molecules can be made.

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The phosphorus pentoxide used to produce phosphoric acid for cola soft drinks is prepared by burning phosphorus in oxygen.

(a) What is the limiting reactant when 0.200 mol of P 4 and 0.200 mol of O 2 react according to P 4 + 5 O 2 P 4 O 10

(b) Calculate the percent yield if 10.0 g of P 4 O 10 is isolated from the reaction.

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Would you agree to buy 1 trillion (1,000,000,000,000) gold atoms for $5? Explain why or why not. Find the current price of gold at http://money.cnn.com/data/commodities/ ( 1 troy ounce = 31.1 g )

This amount cannot be weighted by ordinary balances and is worthless.

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Questions & Answers

is methane a molecule
Okologwu Reply
yes
Miriam
no
rilwan
calculations for solubility
malachi Reply
Whats d IUPAC Numenclature of bromine
Emmanuel Reply
The common name is therefore propyl bromide . For the IUPAC name , the prefix for bromine (bromo) is combined with the name for a three-carbon chain (propane), preceded by a number identifying the carbon atom to which the Br atom is attached, so the IUPAC name is 1-bromopropane.
crystal
What is Quantum number
Derick Reply
what are the chemical properties of group IIA Element and their atomic structure?
NATHAN Reply
What is mixture
Azeez Reply
A mixture is a mix of substances that can be separated
Lillie
what is quantum number
Baba Reply
Hmm
kedis
I suck at chemistry I need a tutor
kedis
h20 hydrates, nitrogen/dry ice lowers pressure similar to space environment when heated at what location/temp.? +or-, expect location (xyz)
Brian
hey kedis,never say that u suck,u don't,all u need is to calm down,get the book and get the points,no need to read it word by word or a-z. ur good bro,u r veeeery intelligent
UDUJI
awwwww
Cereal
what's neuron?
Kelvin Reply
neuron or neutron?
John
cell of the nerve
Kamaluddeen
neuron
rilwan
prepare a solution of 1m iodine in 250mls of water
Dj Reply
Really
Wisdom
Hiiii am new here
Wisdom
Really
Wisdom
WHAT IS CHEMISTRY?
RJ
Chemistry is the study of matter
Wisdom
chemistry is the study of matter and changes it undergoes
Mercy
what is equilibrium
Fatai Reply
what is biology
Fatai
biology is said to be the science of studying life and living organism including theirs physical structure,chemical processes, molecular interaction development and evolution
David
atomic number of sodium
bose
that'll be 11
Kamaluddeen
ok
bose
anymore questions 😁
Franklin
re u writing jamb
bose
please, how man Bond are present when a methane under goes a complete combustion
moses Reply
Combustion of Methane The reactants are on the left side of the equation and the products are on the right. In the reaction, the bonds in the methane and oxygen come apart, the atoms rearrange and then re-bond to form water and carbon dioxide.
saidi
how is ethanol produced using ethene
Glory
Ethanol is manufactured by reacting ethene with steam. The reaction is reversible, and the formation of the ethanol is exothermic. Only 5% of the ethene is converted intoethanol at each pass through the reactor
saidi
Ethanol can be made by reacting ethene (from cracking crude oil fractions) with steam. A catalyst of phosphoric acid is used to ensure a fast reaction. Notice that ethanol is the only product. The process is continuous – as long as ethene and steam are fed into one end of the reaction vessel, ethano
saidi
the mole concerpt and its tricks
Mary Reply
what are atoms
ola Reply
the individual elements of matter.
Reginald
tiny particles that make up a all matter.
Reginald
smallest particles of an element
Osuji
What is the meaning of hybridization
JOSEPH Reply
Differentiate between latent heat and specific latent heat of fusion and vaporization
Amos Reply
Ans: The amount of heat energy released or absorbed when a solid changing to liquid at atmospheric pressure at its melting point is known as the latent heat of fusion. while Vaporization of an element or compound is a phase transition from the liquid phase to vapor.
Acquah
Practice Key Terms 5

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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