Biology; Chemistry; Physics: Post your doubts here!

[funky brat]

in question 4 (b), the marking scheme says that
water present in soil;
absorbed by root;

y is it absorbed?
doesn't water move in to the root hair cells by osmosis
if i wrote water moves in to the root hair cell by osmosis, will my statement be wrong?

No that won't be wrong. Since this question is from ecology so they are talking in more general terms. It would be correct even if you used purely environmental term such as 'interception'.

 

[♣♠ MagneD ♣♠]

I think it's about the formation of products.

In a reversible reaction, if one reaction is having more effect, due to temperature or pressure, and more products are being formed, the position of equilibrium will be in the direction of its products.

like my post i tried my best ....
but .... m weak in this topic

 

[fantastic girl]

Pressure and TEMPERATURE both have effect on RATE OF REACTION?

Position of Equilibrium. What is that? :/

yeh bro....didnt u learn the rules?
High temperature favors endothermic reaction
High pressure favors side wid less no.of moles
and vice versa

 

[black widow]

position means it will either be forward or baCkward reaCtion.... IS IT RIGHT???

position of equilibrium is related to the reaction which will occur

to be more concise, it describes the reaction that actually occurs

for example
3H2 + N2 ---------> 2NH3 Enthalpy change = negative

there are a greater no. of moles on the reactant's side
if we increase the pressure, greater no. of successful collisions will occur in a unit time, and thus more NH3 will be formed
thus the POSITION OF EQUILIBRIUM will shift to the RIGHT

 

[♣♠ MagneD ♣♠]

Sufficient for me guys.......

 

[black widow]

No that won't be wrong. Since this question is from ecology so they are talking in more general terms. It would be correct even if you used purely environmental term such as 'interception'.

but y hasnt the marking scheme used osmosis then?

 

[black widow]

yeh bro....didnt u learn the rules?
High temperature favors endothermic reaction
High pressure favors side wid less no.of moles
and vice versa

that is the simplest way to put it

 

[black widow]

like my post i tried my best ....
but .... m weak in this topic

dont worry, make sure to practice past papers
u will soon grip the concept
and if u still dont understand it, do post the link here and we will help u understand it

 

[fantastic girl]

that is the simplest way to put it

Thanks

 

[funky brat]

but y hasnt the marking scheme used osmosis then?

As I told you they are using general terms. The question focuses on 'Water Cycle' and mentioning the mechanism that causes the absorption of water in plant is preferred the least.

 

[♣♠ MagneD ♣♠]

but y hasnt the marking scheme used osmosis then?

no need to worry ....
many a times i saw that in mark scheme simple language is used when i was solving past papers....

 

[Nabeel.Ahmad]

position of equilibrium is related to the reaction which will occur

to be more concise, it describes the reaction that actually occurs

for example
3H2 + N2 ---------> 2NH3 Enthalpy change = negative

there are a greater no. of moles on the reactant's side
if we increase the pressure, greater no. of successful collisions will occur in a unit time, and thus more NH3 will be formed
thus the POSITION OF EQUILIBRIUM will shift to the RIGHT

Omg!

So, in a reversible reaction, two reactions occur at the same time.
Like in the industrial manufacture of Ammonia, by using Nitrogen and Hydrogen.

In the reaction chamber, those two gases are reacting, and simultaneously Ammonia that is formed, is also decomposing into Nitrogen and Hydrogen.

THAT IS A REVERSIBLE REACTION ^

And in any reaction, increasing the temperature, increases the rate of reaction. So does increasing the pressure.

N2 + 3H2 --> 2NH3

The reactants Nitrogen and Hydrogen are combining, the molecules are colliding with each other, and successful collisions are resulting in the formation of Ammonia gas.
And Ammonia, is decomposing due to high temperature back into Nitrogen and Hydrogen.
The forward reaction is EXOTHERMIC. Energy is being consumed when the bonds in Nitrogen and Hydrogen are broken, but when the N-H bond is formed thrice, more energy is released. So the net energy change is EXOTHERMIC. More energy is released and less energy is consumed.
So the FORWARD REACTION IS EXOTHERMIC.

The backward reaction on the other hand, is ENDOTHERMIC.
Ammonia is decomposing, breaking down, into NITROGEN and HYDROGEN.
The strong covalent bonds in AMMONIA, are broken down, and a lot of energy is consumed, and less energy is released when the N2 and H2 bonds are formed, so the backward reaction NET ENERGY CHANGE is ENDOTHERMIC.

Now, A high temperature favours ENDOTHERMIC REACTIONS, as in them heat needs to be absorbed.
A low temperature favours EXOTHERMIC REACTIONS.

So, in that Haber Process reaction, if we increase the temperature of the reaction chamber, the backward ENDOTHERMIC REACTION will be favoured and more AMMONIA will decompose into Nitrogen and Hydrogen, and less will be formed. So we will say that the POSITION OF EQUILIBRIUM has shifted to the left.
But if we decrease the temperature, the forward EXOTHERMIC REACTION will be favoured, and more AMMONIA will be produced, and less will be decomposed due to a low temperature which won't favour decomposition.

The Position of Equilibrium will shift to the right, resulting in a greater yield of AMMONIA.

But Pressure, too, has an affect on reactions. Since the left side has more moles, and two GASES are combining two form ONE PRODUCT, the greater the PRESSURE, the more the collision between their molecules and the greater will be the rate of forward reaction and more AMMONIA will be produced.
But if pressure is lowered, the rate of backward reaction will increase, leading to more decomposition, and yield of AMMONIA will reduce.

So the Haber Process is designed to form Ammonia, they require MAXIMUM YIELD OF AMMONIA.
And that can be achieved by having as less temperature as possible, and a very high pressure. As that would favour foward exothermic reaction, and reduce the rate of backward reaction, shifting equilibrium to the right.
But by lowering the temperature too much, the yield of AMMONIA increases, sure. But the rate becomes too slow, and it takes a lot of time.
That is why they have fixed a temperature of 450 Degree celsius, as a lesser temperature would slow down the reaction too much.

And the pressure is 200 atm, i think. More than this would be too economical.

 

[♣♠ MagneD ♣♠]

Omg!

So, in a reversible reaction, two reactions occur at the same time.
Like in the industrial manufacture of Ammonia, by using Nitrogen and Hydrogen.

In the reaction chamber, those two gases are reacting, and simultaneously Ammonia that is formed, is also decomposing into Nitrogen and Hydrogen.

THAT IS A REVERSIBLE REACTION ^

And in any reaction, increasing the temperature, increases the rate of reaction. So does increasing the pressure.

N2 + 3H2 --> 2NH3

The reactants Nitrogen and Hydrogen are combining, the molecules are colliding with each other, and successful collisions are resulting in the formation of Ammonia gas.
And Ammonia, is decomposing due to high temperature back into Nitrogen and Hydrogen.
The forward reaction is EXOTHERMIC. Energy is being consumed when the bonds in Nitrogen and Hydrogen are broken, but when the N-H bond is formed thrice, more energy is released. So the net energy change is EXOTHERMIC. More energy is released and less energy is consumed.
So the FORWARD REACTION IS EXOTHERMIC.

The backward reaction on the other hand, is ENDOTHERMIC.
Ammonia is decomposing, breaking down, into NITROGEN and HYDROGEN.
The strong covalent bonds in AMMONIA, are broken down, and a lot of energy is consumed, and less energy is released when the N2 and H2 bonds are formed, so the backward reaction NET ENERGY CHANGE is ENDOTHERMIC.

Now, A high temperature favours ENDOTHERMIC REACTIONS, as in them heat needs to be absorbed.
A low temperature favours EXOTHERMIC REACTIONS.

So, in that Haber Process reaction, if we increase the temperature of the reaction chamber, the backward ENDOTHERMIC REACTION will be favoured and more AMMONIA will decompose into Nitrogen and Hydrogen, and less will be formed. So we will say that the POSITION OF EQUILIBRIUM has shifted to the left.
But if we decrease the temperature, the forward EXOTHERMIC REACTION will be favoured, and more AMMONIA will be produced, and less will be decomposed due to a low temperature which won't favour decomposition.

The Position of Equilibrium will shift to the right, resulting in a greater yield of AMMONIA.

But Pressure, too, has an affect on reactions. Since the left side has more moles, and two GASES are combining two form ONE PRODUCT, the greater the PRESSURE, the more the collision between their molecules and the greater will be the rate of forward reaction and more AMMONIA will be produced.
But if pressure is lowered, the rate of backward reaction will increase, leading to more decomposition, and yield of AMMONIA will reduce.

So the Haber Process is designed to form Ammonia, they require MAXIMUM YIELD OF AMMONIA.
And that can be achieved by having as less temperature as possible, and a very high pressure. As that would favour foward exothermic reaction, and reduce the rate of backward reaction, shifting equilibrium to the right.
But by lowering the temperature too much, the yield of AMMONIA increases, sure. But the rate becomes too slow, and it takes a lot of time.
That is why they have fixed a temperature of 450 Degree celsius, as a lesser temperature would slow down the reaction too much.

And the pressure is 200 atm, i think. More than this would be too economical.

FANTASTIC MAN ... TOO GOOD ,TOO GOOD ....
MY DOUBT IS SOLVED CLEARLY MAN
I *BOW* YOU...

 

[sweetiepie]

FANTASTIC MAN ... TOO GOOD ,TOO GOOD ....
MY DOUBT IS SOLVED CLEARLY MAN
I *BOW* YOU...

Lolzz

 

[Nabeel.Ahmad]

FANTASTIC MAN ... TOO GOOD ,TOO GOOD ....
MY DOUBT IS SOLVED CLEARLY MAN
I *BOW* YOU...

Cool.
And No problem.

 

[funky brat]

Cool.
And No problem.

You read this topic from Federal?

 

[Nabeel.Ahmad]

You read this topic from Federal?

I just remember my teachers lecture. And used the discussion here, and linked everything up.

 

[♫Prince Shah♫]

if there are a greater no. of moles on the reactants side and fewer on the product's side, then increasing the pressure will shift the POSITION OF THE EQUILIBRIUM towards the right and the RATE OF REACTION will increase for both the forward and backward reactions, but the forward reaction will increase more

if we increase the temperature of an Endothermic reaction, then the POSITION OF EQUILIBRIUM will shift towards the right, the opposite for Exothermic reactions
the RATE OF REACTION will increase for both cases (endothermic or exothermic)

it helped meh too brox

 

[black widow]

it helped meh too brox

glad that my post helped u

 

[♫Prince Shah♫]

glad that my post helped u

may i join uh guys in helping ???