Results for Basic science

## Physics: Fundamental, derived quantity, Units, and Dimensions.

August 16, 2019
Fundamental Vs Derived quantity

Fundamental quantities

These are independent quantities with units. The dimension of a physical quantity indicates how it is made up in terms of S.I base quantity.

In other words, the physical quantities is said to have been expressed in terms of fundamental units [Length (L), Mass (M), Time (T), kelvin (k), mole etc].

Quantity Dimension

length         L
Mass          M
Time           T
Kelvin        K
Mole          m

Derived quantities:

These are obtained by some simple combinations of the fundamental quantities and units.

They are thus, dependent on the fundamental quantities and units. Example of the derived quantities, their derivation and their units are summarised in the table below:

 Derived quantity Derived unit Dimension Area  (length x breadth) m^2 L^2 Volume(length x breadth x height) m^3 L^3 Density (Mass/volume) kg/m^3 M/L/L Velocity (Displacement/time) m/s L/T Acceleration (Velocity/time) m/s/s L/T/T force (Mass x acceleration Newton (N) ML/T/T Energy & work (force x distance). joules ML^2/T/T power (work/time) joules/s ML^2/T/T/T Momentum (Mass x velocity) kg m/s ML/T Pressure  (force/area) N/m^2 ? Frequency (no of oscillation/time) 1/s 1/T

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Example

What is the dimension of EMF?

EMF(Electromotive Force) is a derived quantity. It is work done by the chemical force to move unit positive charge from negative terminal to positive terminal of the battery.
EMF = Workdone / charge
Work=Force * displacement
=MLT^-2 * L =ML^2T^-2
Charge=Current * time
=IT
Now,
Dimensional formula of
EMF=Work/charge
=ML^2T^-2 / IT
=ML^2T^-3I^-1

Exercise:

What is the dimension of pressure?

Solution
Watch how to derive the dimension of Pressure.

Conclusion

A  derived quantity is derived from fundamental quantity, simple and short. I hcomments article was helpful. If you have any questions or comments, please don't hesitate to write it in the comments section. All comments are appreciated.

Physics: Fundamental, derived quantity, Units, and Dimensions. Reviewed by uyi osamudiamen Lucky on August 16, 2019 Rating: 5

## Chemistry: What is Hydrogen? It's Uses, physical properties, chemical properties and methods of preparation

August 16, 2019

Hydrogen is found in group one of the periodic table. Though, it is non-metal, it is usually placed in group one because it has one valence electron.

Physical Properties of Hydrogen
•  It is a colourless, odourless and tasteless gas.
• It is neutral to litmus paper.
• It is insoluble in water.
• It is the lightest substance known.
• It has a very low boiling point of (-253-degree Celsius).
• It is less dense than air.

Chemical Properties of Hydrogen

1. It reacts with metals to found hydrides.

2Na + H2 ---> 2NaH

2. It burns in air to produce steam.

H2O + O2 ---> 2H2O

3. It reacts with halogens to produce halides

H2 + Cl ---> 2Hcl
H2 + 2Br ---> 2HBr

4. Acts as a Reducing agent: It reduces oxides to their respective metals

CuO + H2 ---> Cu + H2O

Uses of hydrogen
• It is used in the hydrogenation of oil.
• It is used to manufacture soap and margarine (saponification).
• It is used in filling balloons.
• Liquid hydrogen is used for rocket fuel.
• It is used for welding metals.

Isotopes of hydrogen

Hydrogen has three naturally occurring Isotopes. There are;
• Protium – ( 11H )
• Deuterium – ( 12H )
• Tritium - ( 13H )
“Deuterium oxide” is commonly known as heavy water because it is about 1.1 times heavier than water.  “Protium” has no neutrons, it is the ordinary isotope of hydrogen. “Tritium” is radioactive and rarely found in ordinary hydrogen.

Laboratory Preparation of hydrogen

Hydrogen can be prepared in the laboratory by;

* Action of dilute acid on metal.
* Action of cold water on sodium.
* Action of steam on red hot iron

Laboratory preparation of hydrogen by the action of dilute acid on metal.

AIM – To prepare hydrogen.

APPARATUS – Round bottom flasks, delivery tube, glass jar, thistle funnel, trough etc.

METHOD
• Place some pieces of zinc metal in a round bottom flasks
• Set up the apparatus.

• Add dilute sulfuric acid (H2SO4) to zinc metal through the thistle funnel.
• Collect the gas formed over water.

OBSERVATION – As soon as the metal effervescence occurs, gas liberated is collected over water.

CONCLUSION – Hydrogen can be prepared in the laboratory

Industrial preparation of hydrogen

Hydrogen can be prepared in large quantities in the industries by the following ways;
• Water Gas
• Hydrocarbon
• Electrolysis

By Water Gas

When steam is passed over red hot coke at a temperature of about 1100 degree Celsius. The mixture of carbon (ii) oxide or hydrogen gas is produced and this is known as water gas.

H2O + C ---> CO + H2

The product obtained is mixed with excess steam and passed over iron(iii)oxide or Uranium (iii) oxide as a catalyst at a temperature of 450 degree Celsius.

During this process, carbon (ii) oxide in water gas is converted to carbon (iv) oxide and the liberation of excess hydrogen.

CO + H2 + H2O ---> CO + H2

Questions? Comment below.

Chemistry: What is Hydrogen? It's Uses, physical properties, chemical properties and methods of preparation Reviewed by uyi osamudiamen Lucky on August 16, 2019 Rating: 5

## Physics: Mass and Weight, relationship, differences and related questions

August 16, 2019

### Mass

A mass of a body is the quantity of matter contained in that body. It is a scalar quantity I.e. it has magnitude but no direction. The unit of mass is kilogramme (kg).

### Weight

This is a measure of the force of gravity of the earth on a body. It is a gravitational pull of the earth on any body towards its centre. It is a vector quantity I.e. it has magnitude as well as direction. The unit of weight is Newton (N).

### Relationship between mass and Weight

Weight of a body = Force
Force = mass of body x acceleration due to gravity
I.e. W = F =  mg
m = W/g

For example:

Find the weight of a ball if the mass of the ball is 10kg and the acceleration to gravity is 10m/s2.
Solution
W = mg
W = 10 kg x 10 m/s2
W = 100N

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### Difference between mass and Weight

1)  Mass is the quantity of matter contained in a body While weight is the measurement of the force of gravity on a body.
2) Mass is a scalar quantity while weight is a vector quantity.
3) The S.I. unit of mass is kilogramme while the S.I. unit of weight is Newton.
4) Mass of the body is constant throughout the universe, while weight varies from place to place in the universe.
5) The instruments  used to measure mass can be beam balance, lever balance or chemical balance, while the instrument used to measure weight is spring balance.

### Read on the Equations of motionMass and weight - on moon    An astronaut on earth weighing 980N and mass of 100kg (acceleration due to gravity on earth is 9.8m/s^2).

Weight on Earth: 100kg x 9.8m/s2 = 980N.

Weight on Moon: 100kg x 1.622 m/s2 = 162.2N.

Observation
The same astronaut on the moon would weigh 162.2N and have a constant mass of 100kg (acceleration due to gravity is 1.622m/s^2)

### Related Questions

1)  The mass of a rock on the Earth is 2.0 kg. What is the mass of the rock on the Moon?
A) 1.7
B) 2.0
C) 3.5
D) 20.0

2) Why is weight not equal everywhere?
A) Because of altitude.
B) Because of the varying mass other planets when compared with earth.
C) Because of force of gravity
D) All of the above
E) None of the above

3) An astronaut of mass 40 kg jumped out of the rocket after it had landed on Jupiter.  The astronaut took 0.40 s to drop for 2.0 m. What was the weight of the astronaut on Jupiter?
A) 500
B) 1000
C) 800
D) 2000

4) A student's weight on Earth is 100 pounds. If this student went to the Moon,what  would he weigh?
A) more
B) less
C) the same

Do you know any of the answers? If so share it or ask for it. Do you have any other mass and Weight related questions? Ask it and I will be happy to answer it or send you a detailed solution. Responses are within 24hrs.

Physics: Mass and Weight, relationship, differences and related questions Reviewed by uyi osamudiamen Lucky on August 16, 2019 Rating: 5

## Isotopy and Isotopes; definition,questions and solution. - chemistry

August 16, 2019

Isotopy and isotopes

Isotopy can be defined as a process/occurrence/phenomenon whereby an element has the same atomic number (i.e the number of protons) but different mass number (i.e number of neutrons).

• Proton
• Neutron
• Electron

Isotopes are the elements that have the same atomic number (number of protons) and different mass number (number of neutrons). Examples of isotopes are;

Chlorine    3517Cl , 3717Cl

Oxygen        168O , 178O , 188O

Hydrogen     11H ,21 H , 31H

Carbon          126C , 136C

Sodium      2311Na , 2411Na

Lithium           63Li  , 73Li

Worked Examples:
Question 1
there are two isotopes of chlorine with mass numbers 35 and 37 respectively. if the isotopes exist in the ratio 3:1 , the lighter isotope being more abundant. what is the relative atomic mass of chlorine?

solution
1st isotope   35Cl
2nd isotope   37Cl
the isotopic ratio = 3:1
Total ratio = 3 + 1 = 4
% abundance of  35Cl = (3/4 x 100) = 75%
% abundance of  37Cl = (1/4 x 100) = 25%
Relative atomic mass of chlorine (R.A.M) = (75/100 X 35) + (25/100 X 37) = 3550/100
Relative atomic mass of chlorine (R.A.M) = 35.5

Question 2
Boron exist as an isotopic mixture containing 80% of B , 15% of B and 5% of B. Calculate the  relative atomic mass of Boron?

solution
1st isotope   9B
2nd isotope 10B
3rd isotope 11B
the % abundance ratio = 80:15:5

Relative atomic mass of chlorine (R.A.M) = (80/100 X 9) + (15/100 X 10) +  (5/100 X 11)  = 925/100
Relative atomic mass of boron (R.A.M) = 92.5

Question 3
If the relative atomic mass of natural copper is 63.54. Calculate the proportions of isotopes 63CU and 65CU in the metal?

solution
1st isotope   63Cu
2nd isotope   65 Cu
Let the proportion of cu be x
Let the proportion of cu be y
therefore, x + y = 100  ...................(1)
Relative atomic mass of copper (R.A.M) = (x/100 X 63) + (y/100 X 65) = 63.54
63.54 = 0.63x + 0.65y   .............(2)
from equation (1);  y = 100 - x
substitute for y in the equation (2) above  63.54 = 0.63x + 0.65(100 - x)
63.54 = 0.63x + 65 - 0.65x
1.46 = 0.02x
x = 0.73 (=73%)
recall; y = 100 - x
y = 100 - 73
y = 27%

Question 4
Two isotopes of z with mass number 18 and 20 are in the ratio 1:2. Determine the relative atomic mass.

solution
1st isotope   20Z
2nd isotope  18 Z
the isotopic ratio = 1:2
Total ratio = 2 + 1 = 3
% abundance of  20 Z = (2/3 x 100) = 66.6%
% abundance of  18 Z = (1/3 x 100) = 33.3%
Relative atomic mass of Z (R.A.M) = (66.6/100 X 20) + (33.3/100 X 18) = 1931.4/100
Relative atomic mass of Z (R.A.M) = 19.314.

Isotopy and Isotopes; definition,questions and solution. - chemistry Reviewed by uyi osamudiamen Lucky on August 16, 2019 Rating: 5