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Application of Gay-Lussac’s Law of Combining Volumes

Gay Lussac’s of combining volumes states that gases react in simple ratio with one another and to volumes of the products provided that temperature and pressure remain constant. In this article, you will understand how to apply this law in calculation by studying the following examples below: 1.     2H 2 + O 2 → H 2 O In the reaction above, what volume of hydrogen would be left over when 300cm 3 of oxygen and hydrogen are exploded in a sealed tube?   1cm 3 of oxygen = 2cm 3 of hydrogen 300cm 3 of oxygen = 2 x 300 = 600cm 3 Volume of left over = 1000 – 600 = 400cm 3 2.     Calculate the volume of carbon (II) oxide required to react with 40cm 3 of oxygen. 2CO + O 2 → 2CO 2 1cm 3 of oxygen = 2cm 3 of CO 40cm 3 of oxygen = 2 x 40 = 80cm 3 3.     Calculate the volume of residual gases that would be produced when 100cm 3 of sulphur (IV) oxide reacts with 20cm 3 of oxygen    2SO 2 + O 2 → 2SO 3 1cm 3 of O 2 = 2cm 3 20cm 3 of O 2 = 2 x 20 = 40cm 3
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Stoichiometry Tutorial Step by Step

 


Stoichiometry is the study of the quantity of the reactants and products involved in a chemical reaction. It can also be defined as the determination of the ratio in which elements or compounds react with one another in a chemical reaction.

Method Calculating Stoichiometric Problems

In stoichiometric calculation, the basic method of calculating the problems is by converting one quantity to another using the conversion factors which are usually found in a balanced chemical equation. These conversion factors are the important ratios which can be turned into a fraction to produce the desired results. The molar mass of a substance is one of the important conversion units which is defined as the mass of one mole of a substance expressed in grams.

Types of Stoichiometry Calculations or Problems

There are four basic types of stoichiometry calculations which include:

1.       Mass-to-mass conversion

2.       Mass-to-mole conversion

3.       Mole-to-mass conversion

4.       Mole-to-mole conversion

Gas Stoichiometry Calculations or Problems

In gas stoichiometry problems, there are three types of calculations. Such as:

1.       Mole to volume or volume to mole

2.       Mass to volume or volume to mass

3.       Volume to volume

How to Solve Stoichiometry Calculation

1.       Write a balanced chemical equation of the reaction

2.       Convert the units of a given substance to moles where necessary

3.       Use the mole ratio to calculate the mole of the substance

4.       Convert moles to the required substance to the desired units

Example of Stoichiometry Questions and Answers

1.       Mass-to-mass conversion

Calculate the mass of copper that will be deposited if 20g of zinc reacts with excess copper (II) chloride (Zn = 65.4, Cu = 63.5)

Zn(s) + CuCl2 (aq) → ZnCl2(aq) + Cu(s)

 

From   the equation,

65.4g of Zn = 63.5g of Cu

20g of Zn = 63.5/65.4 x20 = 19.4g

2.       What mass of iron(II)diiron(III)oxide would be produced if 25g of iron was combined with excess oxygen?

(Fe = 55.8, O = 16)

3Fe(s) + 2O2 → Fe3O4(S) 

 

From the equation,

3x 55.8g of Fe = 231.4g of Fe2O4

167.4g of Fe = 231.4g of Fe2O4

25g of Fe = 231.4/167.4 x 25 = 34.6g

 

 

Mass to Mole Conversion

3.       How many moles of silver will be deposited from a silver trioxonitrate (v) solution by 26g of copper? (Ag = 106, Cu = 64)

2AgNO3 + Cu → Cu(NO3)2  + 2Ag

From the equation,

 64g of Cu = 2 moles of Ag

26g of Cu = 2/64 x 26 = 0.81 mole of Ag

 

4.       If 10g of zinc reacts with excess hydrochloric acid, calculate the number of moles of hydrogen liberated (Zn = 63, 1 mole of any gas at S.T.P = 22.4dm3

Zn(s) + 2HCl(aq)  → ZnCl2(aq)  +  H2(g)    

From the equation,

63g of Zn = 1mole of H2

10g of Zn = 1/63x10 = 0.159mole

Mole to Volume conversion

5.       If 30g of sodium trioxocarbonate(IV) reacts with excess hydrochloric acid, what volume of carbon (Iv) oxide would be liberated?

(Na2CO3 = 106. Molar volume = 22.4dm3)

Na2CO3(s) + 2HCl(aq) →2NaCl(aq) + H2O(l) + CO2(g)

 

From the equation,

First, convert 30g of sodium trioxocarbonate(IV) to moles

 

Mole = reacting/ molar mass = 30/106 = 0.28moles

 

1mole of Na2CO3 = 22.4dm3

0.28moles of Na2CO3 = 22.4 x0.28 = 6.34dm3

 

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Application of Gay-Lussac’s Law of Combining Volumes

Gay Lussac’s of combining volumes states that gases react in simple ratio with one another and to volumes of the products provided that temperature and pressure remain constant. In this article, you will understand how to apply this law in calculation by studying the following examples below: 1.     2H 2 + O 2 → H 2 O In the reaction above, what volume of hydrogen would be left over when 300cm 3 of oxygen and hydrogen are exploded in a sealed tube?   1cm 3 of oxygen = 2cm 3 of hydrogen 300cm 3 of oxygen = 2 x 300 = 600cm 3 Volume of left over = 1000 – 600 = 400cm 3 2.     Calculate the volume of carbon (II) oxide required to react with 40cm 3 of oxygen. 2CO + O 2 → 2CO 2 1cm 3 of oxygen = 2cm 3 of CO 40cm 3 of oxygen = 2 x 40 = 80cm 3 3.     Calculate the volume of residual gases that would be produced when 100cm 3 of sulphur (IV) oxide reacts with 20cm 3 of oxygen    2SO 2 + O 2 → 2SO 3 1cm 3 of O 2 = 2cm 3 20cm 3 of O 2 = 2 x 20 = 40cm 3
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