Introduction to chemistry | Atoms, compounds, and ions |
Chemistry | Khan Academy
Khan Academy
Chemistry is one of the sciences that really just helps us understand and make models and
make predictions about our reality.. And even something like the periodic table of
elements, which you 'll see at the front of any chemistry classroom, you take it for granted..
THis is the product of thousands of years of human beings trying to get to an understanding
of the different complexity in the world.. There are a few of these elements that are
disproportionately showing up in a lot of what we see here. A lot of this is different
compositions of elements like carbon and oxygen and hydrogen. Even. The elements
themselves are made of things like protons and electrons and neutrons that are just
rearranged in different ways to give us these elements. On top of that, we build biology.
We build biology based on molecular interactions. And then from biology you. can build
out on all of everything else. Arguably, there 's an infinite more that we could learn relative
to what we know. And Not one of these is more important than the other..
Q1: How does life exist on earth?
Ans: Life exists on earth due to presence
of equilibrium phenomenon taking place
in
atmosphere.
Example: A natural process in which we
take oxygen and exhale (CO₂)
Q2: How different environmental systems
can exist?
Ans: Many environmental systems
depend for their existence on delicate
equilibrium
phenomenon.
Q3: Define Reactants?
,Ans: Substances that combine during a
chemical reaction are called Reactants.
Q4: Define Products?
Ans: New substances form in a chemical
reaction is called Products.
Q5: Give an example of reactants and
products?
Ans: Consider the reaction:
2H₂ + O₂ 2H₂O
In above reaction H₂, O₂ are reactants
while H₂O is a product.
Q6: What are Irreversible reactions? Give
few characteristics of them?
Ans: “Those reactions in which products
do not recombine to form reactants are
called
Irreversible reactions.”
Characteristics:
(i) These reactions proceed in one
direction only.
(ii) Reactants are completely converted
into products.
(iii) It is represented by a single arrow
between the reactants and products.
Q7: Define Chemical Equilibrium State?
,Ans: When the rate of forward reaction
takes place at the rate of reverse
reaction, the
composition of the reaction mixture
remains constant; it is called Chemical
Equilibrium
Q9: How Dynamic equilibrium is
established?
Ans: If a reversible reaction is allowed to
continue for considerable time without
changing the conditions and rates of
forward reaction and rate of reverse
reaction
becomes equal but take place in opposite
directions this is called dynamic
equilibrium.
Q10: Why at equilibrium state reaction
does not stop?
Ans: It is because of dynamic equilibrium.
Q11: Why equilibrium state is attainable
from either way?
Ans: The concentration of specie at
equilibrium stage attains the same values
whether
, we start the reaction in the vessel in the
forward direction or backward direction.
Q12: What is relationship between Active
mass and Rate of reaction?
Ans: Active mass represents the
concentration in mole dm¯³ and it is
expressed as
square brackets ( ). Rate of reaction is
change in concentration of reactant or
product
divided by the time taken to the change.
It is expressed as R=∆c/∆t. So, when
active
mass of substance change then rate also
change.
Q13: Derive the equilibrium constant
expression for the synthesis of ammonia
from nitrogen and hydrogen?
Ans: The reaction for synthesis of
ammonia is as:
N₂ + 3H₂ 2NH₃
Rf = Kf [N₂][H₂]³
Rr = Kr [NH₃]²
The expression for equilibrium constant of
reaction is:
Chemistry | Khan Academy
Khan Academy
Chemistry is one of the sciences that really just helps us understand and make models and
make predictions about our reality.. And even something like the periodic table of
elements, which you 'll see at the front of any chemistry classroom, you take it for granted..
THis is the product of thousands of years of human beings trying to get to an understanding
of the different complexity in the world.. There are a few of these elements that are
disproportionately showing up in a lot of what we see here. A lot of this is different
compositions of elements like carbon and oxygen and hydrogen. Even. The elements
themselves are made of things like protons and electrons and neutrons that are just
rearranged in different ways to give us these elements. On top of that, we build biology.
We build biology based on molecular interactions. And then from biology you. can build
out on all of everything else. Arguably, there 's an infinite more that we could learn relative
to what we know. And Not one of these is more important than the other..
Q1: How does life exist on earth?
Ans: Life exists on earth due to presence
of equilibrium phenomenon taking place
in
atmosphere.
Example: A natural process in which we
take oxygen and exhale (CO₂)
Q2: How different environmental systems
can exist?
Ans: Many environmental systems
depend for their existence on delicate
equilibrium
phenomenon.
Q3: Define Reactants?
,Ans: Substances that combine during a
chemical reaction are called Reactants.
Q4: Define Products?
Ans: New substances form in a chemical
reaction is called Products.
Q5: Give an example of reactants and
products?
Ans: Consider the reaction:
2H₂ + O₂ 2H₂O
In above reaction H₂, O₂ are reactants
while H₂O is a product.
Q6: What are Irreversible reactions? Give
few characteristics of them?
Ans: “Those reactions in which products
do not recombine to form reactants are
called
Irreversible reactions.”
Characteristics:
(i) These reactions proceed in one
direction only.
(ii) Reactants are completely converted
into products.
(iii) It is represented by a single arrow
between the reactants and products.
Q7: Define Chemical Equilibrium State?
,Ans: When the rate of forward reaction
takes place at the rate of reverse
reaction, the
composition of the reaction mixture
remains constant; it is called Chemical
Equilibrium
Q9: How Dynamic equilibrium is
established?
Ans: If a reversible reaction is allowed to
continue for considerable time without
changing the conditions and rates of
forward reaction and rate of reverse
reaction
becomes equal but take place in opposite
directions this is called dynamic
equilibrium.
Q10: Why at equilibrium state reaction
does not stop?
Ans: It is because of dynamic equilibrium.
Q11: Why equilibrium state is attainable
from either way?
Ans: The concentration of specie at
equilibrium stage attains the same values
whether
, we start the reaction in the vessel in the
forward direction or backward direction.
Q12: What is relationship between Active
mass and Rate of reaction?
Ans: Active mass represents the
concentration in mole dm¯³ and it is
expressed as
square brackets ( ). Rate of reaction is
change in concentration of reactant or
product
divided by the time taken to the change.
It is expressed as R=∆c/∆t. So, when
active
mass of substance change then rate also
change.
Q13: Derive the equilibrium constant
expression for the synthesis of ammonia
from nitrogen and hydrogen?
Ans: The reaction for synthesis of
ammonia is as:
N₂ + 3H₂ 2NH₃
Rf = Kf [N₂][H₂]³
Rr = Kr [NH₃]²
The expression for equilibrium constant of
reaction is:
