Science Teacher

Chemistry
-->Atomic structure

An orbit where electron doesn't lose it energy as it moves within it is called ?

A. Planetary orbit
B. Stationary orbit
C Earth orbit

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Chemistry
-->Atomic structure

As long as an electron moves in an a particular orbit it doesn't lose it energy

A. Yes
B. No
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Chemistry FAQ

A frequently asked question;

Q: How do you even know a reaction is endothermic or exothermic ?

------'Answer '--------

You can deduce if a reaction is exothermic or endothermic from the heat change or enthalpy of the system.
By system, I mean reaction.
Now what is enthalpy or heat change ? Enthalpy is the heat content available in a reaction or system. It is also the amount of energy available in the system.
The symbol from heat change or enthalpy is delta H or a triangle shape written beside an H.
(Check previous post for that).
Now a reaction is EXOTHERMIC if the enthalpy is written in negative figure e.g (delta H = -189°C)
A reaction is ENDOTHERMIC if the enthalpy is written in positive figure e.g (delta H = 189°C)

You can also deduce if a reaction is exothermic or endothermic from the information given in questions.
A question could come in the form ;
The reaction between Nitrogen and Hydrogen to form ammonia gives off heat to the surrounding. What is the coefficient of the heat change or heat type reaction is it ?
The answer is simply exothermic and negative.
The coefficient of the heat change will be negative because it gives off heat to the surrounding a major characteristics of exothermic reaction. (check previous for the definition of exothermic reaction).

Do you get ?
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Happy new year globally.
We'll dwell more on ORGANIC chemistry this year ...
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Consider the reaction:

N₂ + 3H₂ ↔ 2NH₃

all in gaseous state catalysed by iron at 500ᵒC

GIVEN; ΔH = -91ᵒC
what is the effect of temperature on the system ?

---solution-----

from the enthalpy of the system we could deduce that it is an exothermic reaction.
by definition an exothermic reaction gives off heat to the surroundings while endothermic absorbs heat from the surroundings.
since this reaction is exothermic then, the FORWARD reaction gives off heat i.e formation of ammonia while reverse or backward reaction absorbs heat i.e the formation of hydrogen and nitrogen from ammonia back.

Therefore, an increase in temperature favors the BACKWARD reaction. this is because an increase in temperature of a system favours the side absorbing heat and vice versa.

from this reaction , the forward reaction is giving off heat while the backward reaction is absorbing heat so since increase in temp. favors the side which absorbs heat , then an increase in temperature favors backward reaction.

read well and digest
see you in the next post ......

Fact about a system in equilibrium

for a reaction to attain equilibrium;
-It must be in a closed system i.e no energy should be lost through the system or gained into the system
-for the above to be achieved the temperature, pressure and concentration of the system remains constant.
-it must be a reversible reaction (an irreversible reaction cannot attain equilibrium)
-the Gibbs free energy i.e the energy available to do work must be zero, ∆G = 0
-the rate of forward reaction must be equal to backward reaction

keep this for now and watch out for next post ......

Did you know !

That the main constituent of LPG is butane.
It also contains a fraction of ethane and propane.

LPG simply translate to Liquified Petroleum Gas.
It is a gaseous fuel.
Another gaseous fuel is the Natural gas its main constituent is Methane.

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Today's chemistry

In which of the following alternatives was it proved that H20 and H202 obey the law of multiple proportion

A. The hydrogen are combined In a simple ratio of 1:2
B. The hydrogen are combined in a simple ratio of 2:1
C. The oxygen atoms are combined in a simple ratio of 1:2
D. The oxygen atoms are combined in a simple ratio of 2:1
E. None of the above

Today's Biology

A substance that impregnate the walls of a tracheophyte cells to provide a necessary stiffness for structural support is

A. Tanin
B. Chitin
C. Lignin
D. Nectar
E. None of these

Questions on the previously taught today's Biology

DIR: try to answer

1. Which information is given in a species name
A. genus and order
B. Division and genus
C. genus and species identifier
D. Species identifier and phylum

2. To which level of classification does a group closely related species of organisms belong ?
A. Class
B. Order
C. Genus
D. Kingdom

3. Every organism is group under the

A. Kingdom monera , protista , fungi , plantae , animalia
B. Bacteria , Archea and Eukarya
C. Kingdom animalia
D. Domain eukarya

Today's Biology

The three (3) domains of life include;

1. Domain bacteria
2. Domain archae
3. Domain eukarya

All the other six kingdoms are grouped under this thre Domains

1. Under bacteria we have : Eubacteria (true bacteria)

2. Under Archae we have : Archaebacteria

3. Under eukarya falls the remaining four

i Kingdom protista
ii kingdom fungi
iii Kingdom plantae
iv Kingdom animalia

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The maximum number of electrons, present in an orbit whose angular momentum is 2h/pie ?

A. 2
B. 8
C. 18
D. 32

Solution

According to bohr atomic model
Angular momentum of electron equals = nh/ £

Here I'll use the sign £ to mean pie

That is,

mvr = nh/£

But in the question we were given 2h/£

Comparing nh/£ and 2h/£ , we have ;

nh/£ = 2h/£

From here n = 4£h /£h
Then n = 4

You've to understand that the number of electrons in an orbit or main energy level is given as : 2n²
Where n = principal quantum number
From the question n equals 4

Then the number of electrons in the main energy level or orbit is

2n²=2(4)² = 32

Therefore , the max. No of electrons will be 32 electrons
Option (D) ✅️🔰

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Happy teachers day to all educators around the world.

continuation on our ongoing topic MACHINE

Today's lesson will be on LEVER as a type of machine.

LEVER

A lever is a simple machine which is used to do work efficiently. A simple lever work on the principle of moment.

There are three (3) classes of lever.

1. THE FIRST CLASS LEVER
2. THE SECOND CLASS LEVER
3. THE THIRD CLASS LEVER

Each of this are classified in accordance to the position of their load, fulcrum and effort.

quickly what is load, fulcrum or effort ?

LOAD: The load is the object to be lifted or work with.
FULCRUM; Fulcrum act as a hinge for the load and effort.
EFFORT: This is the necessary force needed to be applied.

FIRST CLASS LEVER: This is the type of lever in which the fulcrum is between the effort and load.
by arrangement we will have: EFFORT - FULCRUM - LOAD
examples of first-class lever include scissors, beam balance, see-saw, claw hammer, plier etc.
The MA (Mechanical Advantage) of first class lever is equal to or greater than 1. first class lever is also a force multiplier and this is because a small effort (force) is allowed to move a load to a greater distance.
it lessens the effort (force) required to move the load to a relative small force and multiply it so it continue moving the load even without the addition of extra force again.

stick around for the next post on SECOND CLASS LEVER.
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Quick question

Which type of equilibrium does a rolling ball attain ❓️

A. Stable equilibrium
B. Unstable equilibrium
C. Neutral equilibrium
D. Natural equilibrium

TERMINOLOGIES USED IN MACHINE

Mechanical advantage (MA) :

This is the ratio of the of the load to the effort.
MA is unitless since it is a measure of same quantity

M.A= L
---
E

Where E = effort in Newton. and L= load in Newton.
A greater MA signifies a little effort is needed to overcome the load and vice versa.
M.A is inversely proportional to E.
Machines with greater MA makes work more easier with less effort (you get!)

Mechanical advantage is also called the FORCED RATIO.

VELOCITY RATIO (V.R) :

This is the distance moved by the effort arm compared to the distance moved by the load arm.

V.R = distance moved by effort / distance moved by load.

The V.R varies for different machines just like the MA varies for different machines.

For example in a PULLEY , the number of pulleys indicate the V.R of the machine.
The MA of a pulley is always less than its VR.

EFFICIENCY (Ef):

This can be the ratio of the ratio of the MA to VR

Ef = MA/VR × 100

Or

Ratio of the work OUTPUT to the work INPUT

Ef= work output / work input × 100

On the next post we will discuss different types of machines.
From

Lever
Pulley
Inclined plane
Wheel and axle
Screw jack

Read , take note ✍️ and follow ....🔰

MACHINE

Right from our elementary school days we've learnt that a machine is a device that is used to make our work easier and faster. This is apt.
Any device or appliance that allows you apply a little effort at one point and over come a large force [load] at the other end is a MACHINE.

We will start discussing from our simple machines which we already know before we advance it.

Examples of simple machines around us and in our homes are : scissors , nut cracker , squeezer , wheel barrow , forceps, human arms can also be a simple machine (I know you're surprise😅).

In all this listed above a little force apply at one end can be used to overcome a large load.

A weightless and frictionless machine is called an ideal machine.

In an ideal machine , work input in to the machine equals work out put by the machine.

Input work = Output work (for an ideal machine).

In a more actual sense, ideal machines are almost impossible because a machine without weight and friction doesn't exist.

The work done on the machine is also called the work INPUT while
The work done by the machine is the work OUTPUT.

FOR an ideal machine efficiency is 100%

Since the work INPUT is equal to the work OUTPUT by the machine (No reduction or energy loss).
This is almost impossible in any practical(real) machine. That among other reasons account for why the efficiency of a practical machine isn't 100% .

Efficency of a practical machine < 100%.
Efficency of an ideal machine = 100%.

In a practical machine the work INPUT is always larger than the work OUTPUT because of energy loss due to heat and friction.

If a work of 120J is input into the machine , it may only be able to use 100J to work.

20N may be lost due to heat and friction between the part of the machine. Such machine is 83.3% efficient.

We'll continue in the post....follow and jot 👏✍️🔰

Machine

We kick off today after 10 reactions ....

Do you know ?

That a rocket works on the principle of conservation of linear momentum .

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MACHINE
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Physics objective answers waec 2022 with detailed solution now available...

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venue: whatsapp
schedule: class and past questions wrap up.

When you extend one end of an iron rod, into a stream of fire the other end get hot through ______.

A. Conduction.
B. Convection
C. Radiation
D. Heat capacity

🚧Answer🚧

A is correct as conduction is the transfer of heat energy at a point from one molecules to the other....
As the molecules of the iron rod near the fire get heated the heat is transfer to the other molecules in contact far away.. .. Remember this is only done in conductors like metals

Convection isn't the answer because convection doesn't occur in solids... Those are the two possible answers..

Been a while here... Looking for just 20 students to drill for the forthcoming neco and gce exam...on:
Chemistry and physics

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The electron spin of the 6th electron in a fluorine atom is

A. -½
B. +½
C. +⅓
D. -⅓

++Answer ++

Obviously we know that the spin of an electron is either +½ and -½... So C and D is out of option

Know the number of electrons in fluorine (9)
Write the electronic configuration of flourine
Following aufbau principle ( arrange singly before pairing)


Starting with the up spin[]^[]
Then B ✅