The ideal gas equation

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Room temperature and pressure, RTP
Limitations
At RTP, 1 mol of gas molecules

occupies 24.0 dm3
Conditions are not always room temperature and pressure.
A gas volume depends on temperature and pressure.
Ideal gas equation can calculate a gas volume, V
at any temperature, T
at any pressure, p

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The ideal gas equation
pV = nRT

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Converting units for pV = nRT
Before using pV = nRT,

convert units to m3, K and Pa
cm3 to m3 × 10−6
dm3 to m3 × 10−3
°C to K + 273
kPa to Pa × 103

100 kPa = 100 × 103 Pa

220 cm3 = 220 × 10−6 cm3

Examples

4.0 dm3 = 4.0 × 10−3 m3

48 °C = 48 + 273 = 321 K

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Calculating gas volumes

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Calculating a relative molecular mass

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AN INTRODUCTION TO
ATOM ECONOMY
KNOCKHARDY PUBLISHING

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ATOM ECONOMY
In most reactions you only want to make one of

the resulting products
Atom economy is a measure of how much of the products are useful
A high atom economy means that there is less waste

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ATOM ECONOMY
In most reactions you only want to make one of

the resulting products
Atom economy is a measure of how much of the products are useful
A high atom economy means that there is less waste
ATOM ECONOMY

MOLECULAR MASS OF DESIRED PRODUCT x 100
SUM OF MOLECULAR MASSES OF ALL PRODUCTS

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WORKED CALCULATIONS
Calculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2
Example 1

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WORKED CALCULATIONS
Calculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2

Equation C2H4 + Cl2 ——> C2H4Cl2
Mr 28 71 99
atom economy = molecular mass of C2H4Cl2 x 100
molecular mass of all products
= 99 x 100 = 100%
99

An ATOM ECONOMY of 100% is typical of an ADDITION REACTION

Example 1

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WORKED CALCULATIONS
Calculate the atom economy for the formation of nitrobenzene, C6H5NO2
Example 2

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WORKED CALCULATIONS
Calculate the atom economy for the formation of nitrobenzene, C6H5NO2

Equation C6H6 + HNO3 ——> C6H5NO2 + H2O
Mr 78 63 123 18
atom economy = molecular mass of C6H5NO2 x 100
molecular mass of all products
= 123 x 100 = 87.2%
123 + 18

An ATOM ECONOMY of 100% is not possible with a SUBSTITUTION REACTION

Example 2

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WORKED CALCULATIONS
Calculate the atom economy for the preparation of ammonia from

the thermal decomposition of ammonium sulphate.

Example 3

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WORKED CALCULATIONS
Calculate the atom economy for the preparation of ammonia from

the thermal decomposition of ammonium sulphate.
Equation (NH4)2SO4 ——> H2SO4 + 2NH3
Mr 132 98 17
atom economy = 2 x molecular mass of NH3 x 100
molecular mass of all products
= 2 x 17 = 25.8%
98 + (2 x 17)

In industry a low ATOM ECONOMY isn’t necessarily that bad if you can use some of the other products. If this reaction was used industrially, which it isn’t, the sulphuric acid would be a very useful by-product.

Example 3

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CALCULATIONS
Calculate the atom economy of the following reactions (the required product

is shown in red)
• CH3COCl + C2H5NH2 ——> CH3CONHC2H5 + HCl
• C2H5Cl + NaOH ——> C2H5OH + NaCl
• C2H5Cl + NaOH ——> C2H4 + H2O + NaCl

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CALCULATIONS
Calculate the atom economy of the following reactions (the required product

is shown in red)
• CH3COCl + C2H5NH2 ——> CH3CONHC2H5 + HCl
• C2H5Cl + NaOH ——> C2H5OH + NaCl
• C2H5Cl + NaOH ——> C2H4 + H2O + NaCl

70.2%

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CALCULATIONS
Calculate the atom economy of the following reactions (the required product

is shown in red)
• CH3COCl + C2H5NH2 ——> CH3CONHC2H5 + HCl
• C2H5Cl + NaOH ——> C2H5OH + NaCl
• C2H5Cl + NaOH ——> C2H4 + H2O + NaCl

70.2%

55.8%

33.9%

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OVERVIEW
• addition reactions will have 100% atom economy
• substitution reactions will

have less than 100% atom economy
• high atom economy = fewer waste materials
= GREENER and MORE ECONOMICAL
The percentage yield of a reaction must also be taken into consideration.
• some reactions may have a high yield but a low atom economy
• some reactions may have a high atom economy but a low yield
Reactions involving equilibria must also be considered

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Perform calculations to determine the percentage yield of a reaction
Percentage yield

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In a chemical reaction which is totally efficient all the REACTANTS

are converted into products.
This will give 100% yield.
Most reactions, particularly organic reactions give low yields.
Possible reasons:
Impure reactants.
Product is lost during purification.
Side reactions.
Equilibrium reaction means that a reaction is never completed.

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Definitions
Know that:
The theoretical yield is the maximum mass of products which

would be obtained from the balanced equation.
The actual yield is the mass of products obtained.
The percentage yield = Actual yield x 100%
Theoretical yield
Limiting reactant is the substance present in lowest quantity which determines the actual yield.
Excess – more than the mass determined by the balanced equation is used to maximise product obtained.

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Calculating Percentage (%) Yield
2.3g of sodium reacts with an excess of

chlorine to produce 4.0g of sodium chloride.

(Ar reactants: Na=23 Cl=35.5 Mr product: NaCl= 58.5)

58.5 x 0.1 =

Theoretical yield of NaCl =

5.85g

What is the percentage yield?

% Yield = Actual yield x 100% Theoretical yield

% Yield = 4.0g x 100% = 5.85g

68%

2Na(s) + Cl2(g) ⇒ 2NaCl(s)

= 0.1 mol Na

Theoretically 0.1 mol Na should yield 0.1 mol NaCl

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Calculating Percentage (%) Yield
If 1.2g of magnesium reacts with an excess

of oxygen to produce 0.8g of magnesium oxide…

What is the percentage yield?

% Yield = 0.8g x 100% = 2g

40%

2Mg(s) + O2(g) ⇒ 2MgO(s)

(Ar reactants: Mg=24 O=16 Mr product: MgO= 40)

= 0.05 mol Mg

Theoretically 0.05 mol Mg should yield 0.05 mol MgO

40 x 0.05 =

Theoretical yield of MgO =

% Yield = Actual yield x 100% Theoretical yield

The ideal gas equation

Содержание

The ideal gas equation

Room temperature and pressure, RTP LimitationsAt RTP, 1 mol of gas molecules

The ideal gas equation pV = nRT

Converting units for pV = nRT Before using pV = nRT,

Calculating gas volumes

Calculating a relative molecular mass

AN INTRODUCTION TOATOM ECONOMYKNOCKHARDY PUBLISHING

ATOM ECONOMYIn most reactions you only want to make one of

ATOM ECONOMYIn most reactions you only want to make one of

WORKED CALCULATIONSCalculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2Example 1

WORKED CALCULATIONSCalculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2

WORKED CALCULATIONSCalculate the atom economy for the formation of nitrobenzene, C6H5NO2Example 2

WORKED CALCULATIONSCalculate the atom economy for the formation of nitrobenzene, C6H5NO2

WORKED CALCULATIONSCalculate the atom economy for the preparation of ammonia from

WORKED CALCULATIONSCalculate the atom economy for the preparation of ammonia from

CALCULATIONSCalculate the atom economy of the following reactions (the required product

CALCULATIONSCalculate the atom economy of the following reactions (the required product

CALCULATIONSCalculate the atom economy of the following reactions (the required product

OVERVIEW• addition reactions will have 100% atom economy• substitution reactions will

Perform calculations to determine the percentage yield of a reaction Percentage yield

In a chemical reaction which is totally efficient all the REACTANTS

DefinitionsKnow that:The theoretical yield is the maximum mass of products which

Calculating Percentage (%) Yield2.3g of sodium reacts with an excess of

Calculating Percentage (%) YieldIf 1.2g of magnesium reacts with an excess

Похожие презентации

Room temperature and pressure, RTP
Limitations
At RTP, 1 mol of gas molecules

The ideal gas equation
pV = nRT

Converting units for pV = nRT
Before using pV = nRT,

AN INTRODUCTION TO
ATOM ECONOMY
KNOCKHARDY PUBLISHING

ATOM ECONOMY
In most reactions you only want to make one of

ATOM ECONOMY
In most reactions you only want to make one of

WORKED CALCULATIONS
Calculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2
Example 1

WORKED CALCULATIONS
Calculate the atom economy for the formation of 1,2-dichloroethane, C2H4Cl2

WORKED CALCULATIONS
Calculate the atom economy for the formation of nitrobenzene, C6H5NO2
Example 2

WORKED CALCULATIONS
Calculate the atom economy for the formation of nitrobenzene, C6H5NO2

WORKED CALCULATIONS
Calculate the atom economy for the preparation of ammonia from

WORKED CALCULATIONS
Calculate the atom economy for the preparation of ammonia from

CALCULATIONS
Calculate the atom economy of the following reactions (the required product

CALCULATIONS
Calculate the atom economy of the following reactions (the required product

CALCULATIONS
Calculate the atom economy of the following reactions (the required product

OVERVIEW
• addition reactions will have 100% atom economy
• substitution reactions will

Perform calculations to determine the percentage yield of a reaction
Percentage yield

Definitions
Know that:
The theoretical yield is the maximum mass of products which

Calculating Percentage (%) Yield
2.3g of sodium reacts with an excess of

Calculating Percentage (%) Yield
If 1.2g of magnesium reacts with an excess