Excel-Royal Educational Consults

CHEMISTRY THIS WEEK ON FACEBOOK
This week, I will be posting some questions from our online classes.
I will encourage followers, students ESPECIALLY CANDIDATES FOR THE ONGOING WAEC to attempt these questions in preparation for their examinations.

EXCEL-ROYAL ONLINE CLASSES
END OF THE MONTH CHEMISTRY TEST.
INSTRUCTIONS:This paper contains two sections. Section A is objective and section B is Essay. Answer all questions in section A and answer only THREE questions in section B. Time allowed is 1 hour.

SECTION A: OBJECTIVE (40 MARKS)
1. Chemical changes around us include all except
A. Rusting
B. Fading of coloured cloth
C. Driving
D. Decompositing of green leaves in compost
2. Atomicity of ozone is
A. 1
B. 2
C. 3
3. The percentage of Oxygen in sulphur(iv) oxide [ SO2] is (O= 16, S= 32)
A. 5%. B. 50%. C. 500%. D. 25%
4. We have how many states of matter?
A. 1. B. 3. C. 4 D. 10
5. Calcium has how many valence electrons?
A. 2 B. 6. C. 1. D. 4

6. A change which is easily reversed is called
A. )Temporal change B.) Permanent change. C )material change
7. Chemistry is defined as
A. A branch of knowledge which produces chemicals
B. A branch of science which deals with changes in matter
C. The oldest branch of science
8. Fractional crystalization is a method of separating
A. Crude oil. B. Liquid-liquid mixture. C. Coal. D. Solids of different solubilities.
9. Which of the following is a radical
A.) Cl
B NH4+
C F-
D b and c
10. Calculate the relative molecular mass of Pb(NO3)2 . (P=108, N=14, O=16)
A. 170. B. 222. C. 232. D. 132
11. 3NH3 is
A. 3 moles of ammonium. B. 3 moles of ammonia. C. 6 moles of ammonia
12. How many moles of Hydrogen gas are required to produce 4 moles of water.
2H2 + O2 -->2 H2O
A.2 mol. B. 3 mol C. 4 mol.
13. The smallest particle of matter which can take part in a chemical reaction is
A. Ion B molecules C electrons. D. Atom
14. A hypothesis is different from a chemical law in that
A. A hypothesis is not reasonable why a law is reasonable
B. A hypothesis is a reasonable explanation to observation made while a law is a statement from a scientist
C. A hypothesis is a reasonable explanation to observation while a law is a statement which confirms the hypothesis after extensive tests.
D.none
15. Which is not a property of solid
A. Indefinite shape B. Definite volume. C. Mobility of its particles is by vibration
16. The process by which solid changes to gaseous state is called
A. Crystalization B. Evaporation C. Sublimation D. Condensation

17. During Filtration, the substance collected from the filter paler is called
A. Filtrate B. Residue C. Remnants D. Impurities
18. the product of the reaction is
Ca²+. + OH¹- --> ?
A. CaOH2. B. Ca2OH. C. CaOH. D. Ca(OH)2
19. Which of the following is not a compound
A. NaCl. B. CaCl2. C. H2. D. MgCl2
20. The symbol K stands for
A. Potassium. B. Sodium C. Nitrogen D. Franchium

SECTION B ( ESSAY) .
1I). explain the following;
a. Ions b. Molecules. c. Compound d. Atom e. Mixtures
1II) how many grams of ammonia will be obtained if 30g of Hydrogen was used in the haber process.
N2 + H2 --> NH3
1III) calculate the relative molecular mass of
a) NaOH b) KClO3.
( Na= 23, O= 16, Cl 35, H=1 , K= 39)

2. Mentione any five separation techniques and explain them all.
3a) what is chemistry b) define an atom. c) what is the mass of 3mole of Oxygen gas ? e) what is a radical ?
4a) balance the following equation
I. NH3 + O2 --> H2O + N2
II. Fe + Cl2 --> FeCl3
4b) find the empirical formula of a compound which upon analysis yielded 2g of carbon, O.34g Hydrogen and 2.67 g Oxygen.

For solutions and more, please contact:

Tutor: Osuntoyinbo Joshua Ayodeji (CEO Excel-Royal Educational Consults)
Email: [email protected]
Phone: 08066767822
07084225113

CHEMISTRY THIS WEEK ON FACEBOOK
TOPIC: CHEMICAL BONDING PART 2

In our previous study we explained the meaning of chemical bonding, the conceptual terms involved and finally a type of chemical bonding called IONIC BOND.

We shall now look at covalent bond.

COVALENT BOND.
A covalent bond is a type of bond in which there is a contribution of electron(s) by each atom or a donation of electrons by one atom for SHARING in order to form a new molecule.

Its is very important for students to understand that in covalent bond there's no term as transfer of electrons in any form. Instead electrons are only equally shared by the atoms in the molecule.

For typical instance, if atom A brings one electron and atom B also brings one electron and both join to form a bond, we call such a bond a covalent bond. Because both atoms A and B brought 1 electron each to form a bond. You can obviously see that there was no electron transfer but electron sharing.

Again, in the case where only atom A brings electron to share with atom B to form a bond, we also call this a covalent bond with a special name as DATIVE COVALENT BOND or COORDINATE COVALENT BOND.

Do not mistake a dative bond to an ionic bond because in ionic bond, one atom completely gives out ( transfer ) its electrons to another atom. The atom that gives out do not benefit in the electron it gives out while in dative bond, one atom brings electron and share it with another atom. And the atom that brings the electron also benefits in the electron it brings.

Therefore we can say we have ordinary covalent bond and dative covalent bond.

EXAMPLES OF ORDINARY COVALENT BOND:
1. Methane CH4.

The 1 carbon atom in methane has a total of six electrons with the electronic configuration as:
1s² 2s² 3p² .

1st shell= 2 electrons (1s²)
2nd shell= 4 electrons ( 2s² 2p² )
2, 4
since carbon C is a group IV element, C has 4 valence electrons, this means if carbon wants to form a bond with 4 hydrogen atoms, it needs to collect exactly 4 electrons, one from each Hydrogen atoms.

However, Hydrogen has only one electron, as
1s¹

1st shell= 1 electron (1s¹ )
1

If H gives out the 1s¹ electron, it will be left with no electron and can no longer form bonds, so instead the 4 hydrogen atoms bring 1 electron each making a total of 4 electrons and carbon equally brings the 4 valence electrons and share so that C has a total 8 electrons in valence shell and the 4 H has a total of 2 electrons each in their valence shell.
So that, C has a new configuration as 2, 8 in methane
1st shell = 2 electrons (1s²)
2nd shell = 8 electrons ( 2s², 2p6)

Note the additional 4 electrons came from hydrogen contribution.

Finally the 4 Hydrogen atoms in methane also have a new configuration as 2.
1st shell = 2 electrons ( 1s²)

The additional 1 electrons in all the 4 hydrogen atoms came from C contribution.

Stay connected learning & refreshing your knowledge of Chemistry.
Yours,
Osuntoyinbo J. Ayodeji
CEO, Excel-Royal Educational Consults
08066767822

CHEMISTRY THIS WEEK ON FACEBOOK
Good day, followers, our topic this week shall be:
CHEMICAL BONDING.

Chemical bonding is the combination of two or more atoms to form a new species. This species could be molecules, compounds or charged species as ions or radicals.

There are basically two things that occur during bonding. These are ;

1. Sharing of electrons
2. Complete transfer of electrons

It is very important to understand the difference between SHARING of electrons and TRANSFERRING of electrons. As this is the building block to understanding chemical bonding.

When we say sharing of electrons, we mean both atoms involved in bonding are equally benefiting in the set of shared electrons. For example, if atom A is to share 2electrons with atom B , then both atoms A and B will end up with equal number of electrons that are shared. This means atoms A and B have benefited from the shared electrons.

However, when we say transfer of electrons, we mean that only one of the atoms involved in bonding is benefiting in the set of electrons transferred. By transfer of electrons, one atom completely gives it's valence electrons to another atom without benefiting in the electrons it is giving out. For example; if atom C gives it 1 electron to atom D without benefiting or equally sharing that electron, we say atom C has transferred its electron to atom D.

Having known the difference above, we shall try to identify the types of chemical bonds we have.

1. Ionic bond( elecrovalent bond):
This is a chemical bond in which one atom completely transfers one or more electrons to another atom to form a compound or molecule.
The atom that gives out ( transfer ) its electrons is called the donor atom and the atom that receives the transferred electrons is called the acceptor atom.

Examples:
1. NaCl - sodium chloride.
The bond in NaCl is purely ionic. WHY?

Na is a group1 alkalis metal with 1 valence electron. A valence electron is the electron(s) in the last shell of the atom. So , Na has a configuration of 2, 8, 1.
This means ,
1st shell= 2 electrons. (1s²)
2nd shell= 8 electrons (2s² 2p6)
3rd shell = 1 electron (3s¹)

So Na being a metal, would love to transfer the 1 electron in the 3rd shell (3s¹) and become stable with 8 electrons . the reason why Na will give out the electron instead of accepting is that, Na can only be comfortable when it has 8 valence electrons. And in the 3rd shell it has only 1 electron as 3s¹. This means Na needs additional 7 electrons to obtained 8 valence electrons. But for Na to accept 7 electrons, it will need extraordinary energy, so Na has another option, to use a small amount of energy and give out the last electron and easily remain with 8 electrons in the 2nd shell as 2,8 instead of 2, 8 , 8.

While Cl is a member of groupVIIA or group17 and has 7 electrons in its valence shell as 2, 8 , 7. This means;
1st shell= 2 electrons (1s²)
2nd shell= 8 electrons ( 2s² 2p6)
3rd shell= 7 electrons. (3s² 3p5 )

Therefore Cl needs only 1 electron in the 3rd shell to have 8 valence electrons, so it will accept the electron given out by Na and have a new configuration of 2, 8, 8.

In a summary, Na transfer its 1 valence electron to Cl which accept the 1 electron and a new compound is formed as NaCl.

Note.
Neutral Na atom has the shell configuration as 2, 8 , 1. But in the compound NaCl, Na has a 2, 8. Configuration while Cl has 2, 8,7 and 2, 8, 8 respectively.

Brain Test!

Why would Chlorine prefer to accept 1 electron from sodium instead of giving out its 7 electrons to sodium to form NaCl ?

Send in your response at the Comments section. For questions and more on Chemistry, call: 08066767822.
Remain blessed.

CHEMISTRY THIS WEEK ON FACEBOOK
Friends and followers, it's been a while teaching and learning here. I'm sorry for being offline teaching for a while. I have been involved in some live teachings which has been taking my time. However, pls let's have this for this week.

TOPIC: CALCULATIONS ON CHEMICAL EQUATION (STOICHIOMETRY)

Under this we shall make relationships between reactants and products, reactants and reactants, products and products interchangeably.

This relationship could either be in terms of moles known as mole ratio and mass ratio.

Mole Ratio: this explains the mole relationship between reactants and reactants and products and products, or reactants and products respectively.

This means mole ratio tells you the exact number of moles of reactants and products in an equation. Therefore, when you need to calculate the mole of any unknown reactant(s) or product(s) you will use the mole ratio relationship.

Example:

The mole ratio in the equation below is
2:1:2

-the first two is representing moles of hydrogen gas in the equation.
-the middle one is representing moles of oxygen gas in the equation
-the last two is representing moles of water at the product side in the equation.

Note:
2:1:2 is read as, "2 is to 1 is to 2"

2H2 + O2--> 2H2O

It's important to note that, mole ratio are only correct when a given chemical equation is balanced. Therefore to get the correct mole ratio, you MUST balance the chemical equation correctly.

Example:

H + O --> H20

Don't go a head and give the mole ratio as;

1:1:1

Because the above equation is not balanced. Until you balance it before you give a mole ratio relationship.

2H2 + O2--> 2H2O

2 :1 : 2

The above relationship at the reactants means:

2 mol of H was required to react with 1 mol of O to produce 2mol of water (H2O).

Now a student may ask, "where's the 1 coming from? "
It's coming from the equation as well, since no number was written at the front of O2 that means its 1.

So the mole relationship between Hydrogen gas H2 and Oxygen gas O2 is

2:1

And can be expressed as

2 ----> 1

Mass ratio: this explains the mass relationship between reactants and reactants and products and products, or reactants and products respectively.

To get the mass ratio we use the relative molecular mass of the compounds or molecules in the given equation.
Example:
In

2H2 + O2--> 2H2O

The mass relationship between H and O at the reactants is
H=1. O= 16

2H2= 2(1x2)=4g

O2= 16x2=32g

So the mass ratio will be

4g : 32g

Or expressed as

4g of H ---> 32g of O

E X A M P L E S
1. How many moles of nitrogen gas is required to react with 12 moles of hydrogen gas to yield ammonia ?
N2 + H2 NH3

Solution:
Step1:
We need to balance the above equation before obtaining the right mole ratio.

N2 + 3H2 2NH3

Step2: write the mole ratio from the balanced equation.

1 : 3 : 2

Step3: select the relationship needs to answer the unknown.

In this case, the relationship needed is only between
N2 and H2.

Step4: calculation
1 mol of N2 --> 3 mol of H2 ---equation i
The above means 1 mol of nitrogen gas requires 3 mol of hydrogen gas .

Let the unknown mol of N2 be T.

T of N2 --> 12 mol of H2 --- equation ii

1mol of N2 ---> 3mol of H2
T of N2-----> 12 mol of H2

Cross multiply

T x 3mol = 1mol x 12 mol
3mol.T = 12mol
Divide both sides by 3mol
3mol.T/3mol= 12mol/3mol
T= 4 mol.
Therefore 4 mol of N2 was required to react with 12 mol of H2 to yield ammonia.

2. Calculate the mass of hydrogen gas obtained if hydrogen gas reacted with 8g of nitrogen gas to produce ammonia.
N2 + 3H2 2NH3

Solution.

Step1: since the equation is already balanced, write mole ratio.

1 : 3 : 2

Step2: select the relationship of the unknown in the equation.

Here its between H2 and N2

Step3: we will now write the mass ratio because we are looking for unknown mass of hydrogen gas. To do that, we use the molecular mass of the molecules involved.

N2 + 3H2 2NH3

[ N= 14, H=1]

14x2 : 3(1 × 2) : 2(14) + 2(1×3)
28g : 6g : 34g

Steps4:
Calculation

28g of N2 --> 6g of H2 --equation I

Let the unknown mass of hydrogen be Q

8g of N2---> Q of H2 --equation in

28g of N2--> 6g of H2
8g of N2---> Q of H2

Cross multiply
28g × Q = 8g × 6g
28g.Q = 48g

Divide both sides by 28g
28g.Q/28g = 48g / 28g
Q= 1.7g

Therefore 1.7 g of hydrogen gas was obtained to react with 8g of Nitrogen gas to produce ammonia.

You can join my live classes or Online (via ZOOM) classes as I demystify Chemistry for you.
Contact: 08066767822 via Calls, SMS or Whatsapp. Thank you.
Osuntoyinbo Joshua Ayodeji
CEO Excel-Royal Educational
Consults.

CHEMISTRY THIS WEEK ON FACEBOOK
Dear Facebook followers, our lesson this week is for S.S 2 students. However, other classes and older followers can refresh their knowledge.

TOPIC : ELECTROLYSIS (for beginners)

Some students are always afraid of the topic electrolysis, thinking its too difficult to understand 🙄🤔🥴.
But don't worry you all will have a clear understanding of it.

Electrolysis deals with the use of electric current to make a chemical reaction take place.

To understand electrolysis we must know the following;

1. Standard electrode potential: the standard electrode potential of a metal is the potential difference between the metal and one-molar solution of its ions at 25°C.

Explanations; we have two charges, positive (+) and negative (-). And an electron carry a negative charge which is represented as e- . potential difference is the work done in moving a charge from one place to another. And is measured in volt.
Look at NaCl, we understand that Na has 11 electrons as 2, 8, 1.
Before Na joins (react) with Cl, Na must give that last 1 electron to Cl to form ionic bond. Thus that 1 electron has to move from Na to Cl, and since the electron has a charge, we say the work done as the electron leaves Na to stay with Cl is the potential difference which is regarded as the standard electrode potential.

All ions have their different standard electrode potential.

How do we get the standard electrode potential of an ion?🤔🤔🤔🤔

Its easy, you can get it through experiment using an electrochemical cell set up. Two beakers are always used , one holds the electrode and the metal and the other holds hydrogen ion and hydrogen gas with an electrode and a salt bridge that connects the two beakers and a voltmeter to read the potential difference known as the standard electrode potential.

All scientists have agreed that hydrogen ion (H+) should be given a standard electrode potential of 0 volt at all temperatures. Therefore standard electrode potential is always measured in the presence of Hydrogen ion and Hydrogen gas in one of the beakers.

That is , if I want to find the standard electrode potential of Cu+, then one beaker will have Cu+ and the other must have H+ and hydrogen gas.

During the process electrons move, and as electron move , the voltmeter calculates the potential difference which is taken as the standard electrode potential.

The standard electrode potential can be positive (+) or negative (-) .

How do we know if an ion will have a negative or positive standard electrode potential value ( number)?🤔🤔🤔🤔😒

Its simple , 😱 during the experiment, the voltmeter has a needle that moves and tells you the place where the electron leaves and where it goes, so if the needle points at the side where the metal is, the electrode potential is taken to be negative (-). Example, if the needle points at the side where Cu²+ is and the voltmeter has a value 0.34 volt, it means the standard electrode potential of Cu²+ is +0.34 volt and means electrons travel from the side of H+ /H2 gas to the side of the Cu²+.

And if the needle points at the side of the H+ / H2 gas, then , it means electron moves from Cu²+ to the side of H+ / H2 gas and therefore the standard electrode potential will be taken as -0.34 volt.

2. ELECTROCHEMICAL SERIES: experiment has already been done and the standard electrode potential of all ions are recorded. And from mathematics we understand that a positive number is bigger than a negative number . example +1 is bigger than -1 ,
0 is bigger than -1.

Thus an electrochemical series is a chart that gives the standard electrode potential of ions and their order of reactivity.
😱😱😱
The most reactive metal ion has the smallest standard electrode potential.

ION. STANDARD ELECTRODE POTENTIAL

K+. ----->. -2.92 volt

Ca²+ -----> -2.87 volt

Na+ ------>.-2.71 volt

Mg²+ ---> - 2.37 volt

Al³+ -----> -1.66 volt

Zn²+ -----> -0.76 volt

Fe²+ ------> -0.44 volt

H+ ---------> 0.00 volt

3. REACTIONS: To understand electrolysis you must know what each reaction mean.
Remember I told you that e- means an electron, therefore ;
e- = 1 electron
2e- = 2 electrons
3e- = 3 electrons
4e- = 4 electrons
etc.

Easy right ???🤞🤞🤞
We understand that when writing a chemical reaction equation, anything on your left Hand side is the reactant and anything on your right hand side is the product.

Let's understand some equations
1. Na ---> Na+ + e-

At the left , it means 1 electron has left solid Na atom to give you the ion Na+ at right as the product.
Wow...

Since you started with Na at the left and it was not having a charge, but ended with Na+ which had a charge +1 at right, we say the reaction is an OXIDATION reaction.
So any time the product ends up with a positive charge , we call it an oxidation

2. Ca ---> Ca²+ 2e-

This also means Ca has removed 2 electrons from it to become Ca²+. So since we started with Ca at the left hand and ended with Ca²+ we call the reaction an OXIDATION. Because the oxidation state increased from zero (0) to +2.

Note: all neutral atoms have a zero oxidation state. This means all atoms with no charge have zero oxidation state.

How can I know that an atom can loss a particular number of electrons?

The number of electrons lost are equal to the valency of the atom.

HOWEVER, if we exchange the position of the reactants and products it will change the meaning as well as shown below👇

1. Na+ + e- ---> Na

Here it means Na+ gains 1 electron to become Na. We started with Na+ at left which has a +1 charge and ended up with Na at right which has zero charge, because the charge reduced from +1 to 0 , we say the reaction is a REDUCTION reaction.

Same applies to ;

2. Ca²+. + 2e- ---> Ca

We shall make use of this in electrolysis and determine the half reactions at the anode and cathode and from there write the overall reaction without a problem.
❤❤❤❤

4. DISPLACEMENT / DISCHARGE OF IONS: Displacement simply means the ability of an ion to remove another ion of the same charge in compounds.
Examples, if we have a compound like HCl, and when F- removes Cl from HCl to give a new compound HF , we say F has displaced or discharged Cl- from the compound.

How can we know which ion will displace another ion in a given compound.? 😓😨🥱

Its simple, we make use of the standard electrode potential we learnt and the electrochemical series. All the metal ions that have smaller standard electrode potential and are up will always displace the metal ions below it.

Here's the order for some metal ions :
K+
Ca²+
Na+
Mg²+
Al³+
Zn²+
Fe²+
Sn²+
Pb²+
H+
Cu²+
Ag+

Therefore a metal up can remove a metal down from a compound (displacement). And occupy the position.
Examples
1. 2Na + can remove 2H+ in H2S04 👇

H2SO4 + 2Na---> Na2SO4

But 2H+ can not remove 2Na+ from Na2SO4👇

Na2SO4 + H2 ---> H2SO4

This one is wrong. 🤥🤥🤥 never do it.

However, Ca²+ is above Na+ , but Na+ is more reactive because the big Ca²+ has a higher ionization energy due to greater nuclear charge effect than the small Na+.

Same thing applies to anions

F-
SO4²-
NO3-
Cl-
Br-
I-
OH-

All the ones up will displace the ones down.

We shall continue from here next week. Till then, remember CHEMISTRY IS SIMPLE!

CHEMISTRY THIS WEEK ON FACEBOOK
Good day, Facebook followers. Our Chemistry Class this week shall be for SS 1 students. However, other classes n older followers can refresh their knowledge.

TOPIC: PARTICULATE NATURE OF MATTER.

Matter is anything that has mass and can occupy space.

Matter is made up of particles which are
1.Atoms
2. Molecules
3. Ions

ATOMS:
An atom is the smallest particle of matter that takes part in a chemical reaction. Each element has at least an atom inside it.

MOLECULES:
A molecule is the smallest particle of a compound or substance than will exist alone but will retain the same chemical properties of the compound or substance.
There's a difference between a compound and a molecule, because all compounds are molecules but not all molecule are compounds
Example

A compound is gotten when the elements joining together are different .eg
In water , we have H and O

While a molecule can be gotten when the elements are same or not. E.g

H2. This means H + H --> H2

ATOMICITY:

Atomicity means the number of atoms in a molecule. Note that a compound has same formulae with its molecule.
Since atomicity tells us the number of atoms in a molecule, we have mono-atomic, diatomic and polyatomic molecules.

IONS:
An ion is an atom or group of atoms that have a charge on it.

The atoms that have positive charge on them are called cations. Examples
Na+, Mg²+ , K+ .

The atoms with a negative charge are called anions
Examples

F-, Cl-, Br-, I- SO4²-

RELATIVE ATOMIC MASS.
This is defined as the number of times the average mass of one atom of an element is heavier than one-twelfth the mass of one atom of carbon-12.

Explanations: The above definition means that , the relative atomic mass of any atom is the number of times that atom is heavier than 1 divided by 12 the atom of carbon-12.
The instrument for measuring it is the spectrometer.

2. Relative molecular mass(R.M.M.):
The RMM of an element or compound is the number of times the average mass of one molecule of it is heavier than one-twelfth the mass of one atom of carbon-12.

The relative atomic masses of all elements are calculated using the spectrometer. And all are written on the periodic table as well.

Examples:

1. Calculate the relative molecular mass of limestone given as CaCO3.
Given that : ( Ca= 40, C= 12, O=16).

Solution:

RMM= 40 + 12 + (16 x3)= 100

1. Moles:

Because the particles of matter are so small, we make use of moles to carryout our chemical reactions. Mole is like many particles reacting.

Particles are atoms, ions and molecules which are very small.

Definition: A mole of substance is the amount containing many particles as the number of atoms in exactly 12 grams of carbon -12.
Mole is often written as mol.

Since mole talks about particles in a substance, and its equality with atoms in 12g of carbon-12, a scientist called Avogadro's carried out an experiment and discovered that,
1 mole has 6.02x10²³ atoms
This also means ,

12g of carbon-12 have 6.02x10²³ atoms in it.
We call this number 6.02x10²³ the Avogadro's number.

Molar mass of any substance is the mass of one mole of the substance expressed in grams per mole.

The molar mass is actually gotten the same way as the relative molecular mass.

If we know the mole ratio, we can be able to tell the number of particles in a compound or molecule.

Since mole talks about particles in a substance, and its equality with atoms in 12g of carbon-12, a scientist called Avogadro's carried out an experiment and discovered that,
1 mole has 6.02x10²³ atoms
This also means ,

12g of carbon-12 have 6.02x10²³ atoms in it.
Thus we use this relationship to calculate the particles in a compound or molecule.
Moles = particles / 6.02 x 10²³

This sign / means division.

Examples,

1. How many atoms are in 2mole of water?

Answer:
Use the formula above.
Moles = particles / 6.02 x 10²³

From the question we have:
Moles= 2

Particles= atom
Put the values in the equation

2 = atoms / 6.02x10²³

Make atoms the subject formula by multiplying both sides by 6.02x10²³
This sign / means division

2x 6.02x10²³= atoms

atoms= 1.204x10²⁴

Therefore we have 1.204 atoms of water in 2moles.

Join me again next week for another interesting Topic in Chemistry.
For Questions, pls contact 08066767822 by SMS or Whatsapp.
Do enjoy the week, God bless you all.

CHEMISTRY THIS WEEK ON FACEBOOK
TOPIC: OXIDATION AND REDUCTION (REDOX) REACTION (Cont'd)
Definition of Oxidation & Reduction
*Oxidation is the addition of electronegative elements and the removal of electropositive elements.
*Reduction is the addition of electropositive elements and the removal of electronegative elements.
NOTE:
Electronegative elements are elements that gain electrons. Non metals like Chlorine, Oxygen, Sulphur etc are examples.
Electropositive elements are elements that loose electrons. Metals like Sodium, Potassium, Magnesium etc are examples
Explanation:
Last week, we said that Oxidation and Reduction are two processes that occur together at the same time. As a matter of fact, they are complementary. One help the other to be achieved. Without Reduction, there can't be Oxidation. That is why the reaction is called REDOX REACTION.
Let's take a look at an example:
2Na + Cl2 ---------> 2NaCl
From the above equation:
Considering Sodium (Na) on the left side, had added Chlorine (an electronegative element) at the right hand (product) side, then it (Sodium) can be said to have undergone OXIDATION.
Considering Chlorine (Cl2) on the left hand side, had also added Sodium (an electropositive element) at the right hand(product) side, then Chlorine can be said to have undergone REDUCTION.
Reducing and Oxidizing Agents
From the equation above:
*Sodium (Na) is the substance/reactant that is oxidized (that undergoes oxidation). Therefore, it is the REDUCING AGENT.
Explanation: Elements that accept electronegative elements from another reactant are Reducing Agents.
Chlorine (Cl2) is the substance/reactant that is reduced (that undergoes reduction). Therefore, it is the OXIDIZING AGENT.
Explanation: Elements that accept electropositive elements from another reactants are Oxidizing Agents.
In Summary:
I. Oxidation is the addition of electronegative elements.
II. Reduction is the addition of electropositive elements.
III. Oxidizing Agents are reactants that accept electropositive elements.
IV. Reducing Agents are reactants that accept electronegative elements.
JOIN ME NEXT WEEK SUNDAY EVENING AGAIN as we continue on this topic.
For a private class in Chemistry, we give online or home lessons for students of ALL Classes in chemistry for each topic of your choice at your convenient time.
Phone no: 08066767822, 08158581341
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TOPIC: REDOX REACTIONS.
Redox is simply a short form of Reduction - Oxidation.

RED-Reduction
OX- Oxidation
Therefore a Redox reaction is a reaction in which both reduction and oxidation take place at the same time.

Let us understand some terms:
1. What is Oxidation? 🤔
Oxidation has many definitions and explanations depending on the reactants and products in a chemical equation.
A reactant is any substance that joins chemically with another substance to form something new.
A product is the substance formed.
Example ,
2Fe + 3Cl2 -> 2FeCl3
The reactants are 2Fe and 3Cl2
And the products is 2FeCl3.

1. Oxidation means addition of oxygen to a particular reactant to give a product.
Explanations:
That is any reactant that was not having oxygen at beginning but end up with oxygen at the product means OXIDATION has taken place and when oxygen alone combines with a compound or element , we also say oxidation has happened in that reaction.
Examples:

1. C + 2ZnO --> CO2 + 2Zn

Because carbon(C) is a reactant, and it's not having oxygen at the left, but going to the product at the right, the oxygen(O) from ZnO leaves zinc and combines with Carbon to give CO2, therefore we say oxidation has taken place or we can also say that C is oxidized since oxygen leaves another atom to join it.

2. 2Mg + 02 --> 2MgO

Because oxygen alone is added to Magnesium Mg to have MgO we say oxidation has taken place.

3. 4Na + O2 --> 2Na2O

4. 2Ca + O2 --> 2CaO

5. CH4 + 2O2--> 2H2O + CO2

What is Reduction ?
Reduction is always the opposite of oxidation.
Therefore we can say, Reduction is the removal of oxygen from a reactant.
Explanations:
This means that anytime a reactant is joined with oxygen at the left, but at the right ( product) the reactant no more has oxygen to it we say Reduction has happened. Or anytime a reactant gives it oxygen to another reactant we say reduction has taken place.

Examples:
1. C + 2ZnO --> CO2 + 2Zn

Since Zn has given its Oxygen (O) to C , we say reduction has taken place or we can also say ZnO is reduced.

But you used the same equation for both reduction and oxidation 🤔🤔🤔 why???😫😓😓😓

Its simple, remember I told you that reduction and oxidation can take place at the same time. Because:
In C + 2ZnO--> CO2 +2Zn
A. C takes the oxygen in ZnO to become CO2 we say its oxidation.
B. ZnO gives out it's oxygen to C to become Zn we say its reduction.
Therefore all are happening at the same time, that is why the equation was used in both.

2. 2KClO3 --> 2KCl + 3O2

Because the compound KClO3 loses the 3 oxygen atom from it to become KCl we say its Reduction.

Reducing and Oxidizing Agents.
In this definition of Redox above,

A reducing agent is the reactant that is oxidized.
Explanations: this means the element that collects oxygen from another reactant is the reducing agent.
Example:
In C + 2ZnO --> CO2 + 2Zn
Because Carbon, C collects oxygen to become CO2, we say the Reducing agent is Carbon , C.
Therefore C was oxidized.
😀😀😀
Easy huh

2. An oxidizing agent is the reactant that is reduced.
Explanations: this means the reactant that gives out its oxygen is the oxidizing agent.
Example:

In C + 2ZnO --> CO2 + 2Zn
Because ZnO gives out its oxygen to C to become only Zinc ,Zn we say ZnO is the oxidizing agent since it gives out the oxygen and causes C to be oxidized.
Therefore we can say ZnO was reduced.

In summary :
1.Oxidation is addition of oxygen.
2. Reduction is subtraction or removal of oxygen
3. Reducing agent is the reactant that collects oxygen
4. Oxidizing agent is the reactant that gives out oxygen

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