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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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Work Energy and Power

 Work; This is the product of force and the displacement in the direction of the force.

Work done = force x distance moved in the direction of force

The unit of work done is Joule (J)

How to Calculate Work Done

Example Questions

1.        If a car of mass 80kg moved a distance of 5m. calculate the work done by the car

(g =10m/s2)

 

Solution

Mass = 80kg

Force = 80 x 10 = 800N

Distance = 5m

Work done = 800 x 5 = 4000J

2.       A boy pulls a load of 300N to a distance of 6m. Calculate the work done

 

Solution

Force = 300N

Distance = 6m

Work done = 300 X 6 = 1800J

Energy: This is the ability to do work. It is also measured in Joule (J). Energy has many forms which include:

·         Heat energy

·         Light energy

·         Chemical energy

·         Electrical energy

·         Atomic energy

·         Solar energy

·         Mechanical energy

We are going to be studying mechanical energy. Mechanical energy is divided into two

i.                     Potential energy

ii.                   Kinetic energy

Potential energy: This is stored energy or energy due to the position of an object or due to height.

P.E = mgh

M = mass

G = acceleration due to gravity

H = height of the object

How to calculate the potential energy

Example Questions

1.       Calculate the potential energy of a body of mass 8kg held 5m above the floor (g =10m/s2)

               Solution

P.E = mgh

M = 8kg

G = 10m/s2

H = 5m

P.E = 8 X 10 X 5 = 400J

2.       A loaded sack bag of mass 50kg falls down from the floor of a lorry 4m high. Calculate the work done by gravity on the load. (g = 10m/s2)

Solution

P.E = mgh

       = 50 X 10 X 4 = 2000J

Kinetic energy: This is the energy possessed by a body due to motion

K.E = ½ mv2

Where m = mass

             V = velocity

Example Questions

1.       A mass of 60kg has a velocity of 40m/s. what is its kinetic energy?

 

Solution

K.E = ½ mv2

      = ½ x 60 x 40 x 40 = 48000J

2.       A body has a mass of 20kg. if its kinetic energy is 2000J, calculate its velocity.

 

Solution

K.E = ½ mv2

2000 = ½ x 20 x V2

2000 x 2 = 20 x V2

V2   = 4000/20 = 200

V   = √200   = 14.1m/s

Power: This is the rate of doing work or work done per second.

Power = work done/ time taken

Its unit is J/s of watt (W).

Example Questions

1.       If a water pump can lift 2000kg of water through a vertical height of 20m in 20s. calculate the power of the pump. (g = 10m/s2)

 

Solution

 

Power = work done/ time taken

Force = 2000 x 10 = 20000N

Distance = 20m

Work done = 20000 x20  = 400000J

Power = 400000/20  = 20000w or 20kw

2.       A man whose mass is 80kg walks up a flight of 14 steps each 40cm high in 10s. find the power he develops in watts (g = 10m/s2)

 

Solution

 Power = mgh/time

Distance 14 x 40 = 560cm = 560/100 = 5.6m

Power = 80 x 10 x 5.6/10   = 448W

 

 

 

 

 

 

 

 

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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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