Chemistry: Post your doubts here!

[awesomaholic101]

The 12th question please ... any easy and short method would be highly appreciated

 

[Metanoia]

Q15 how u find total mass?

For the question, its actually 1200 million tonnes (the total mass of limestone).

 

[Metanoia]

how to solve this?View attachment 57378

View attachment 57381

The 12th question please ... any easy and short method would be highly appreciated

2X(NO3)2 --> 2XO + 4NO2 + O2

let x be the Mr of element X

moles of X(NO3)2 = 3/(x+124)

mass of XO = 3 - 1.53 = 1.47 g
moles of XO = 1.47/ (x + 16)

Based on the balanced equation, moles of X(NO3)2 =moles of XO
Therefore, 3/(x+124) = 1.47/ (x + 16)

Solve for x.

 

[awesomaholic101]

2X(NO3)2 --> 2XO + 4NO2 + O2

let x be the Mr of element X

moles of X(NO3)2 = 3/(x+124)

mass of XO = 3 - 1.53 = 1.47 g
moles of XO = 1.47/ (x + 16)

Based on the balanced equation, moles of X(NO3)2 =moles of XO
Therefore, 3/(x+124) = 1.47/ (x + 16)

Solve for x.

oh thank you so much ... i had balanced my equation wrong.

 

[Metanoia]

How do you draw the apparatus to collect water and then N2O?
1c:
papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_s12_qp_52.pdf

Collect the water through condensation.



As for the nitrogen oxide, a gas syringe should suffice.

 

[awesomaholic101]

2X(NO3)2 --> 2XO + 4NO2 + O2

let x be the Mr of element X

moles of X(NO3)2 = 3/(x+124)

mass of XO = 3 - 1.53 = 1.47 g
moles of XO = 1.47/ (x + 16)

Based on the balanced equation, moles of X(NO3)2 =moles of XO
Therefore, 3/(x+124) = 1.47/ (x + 16)

Solve for x.

Is the mass of total products always equal to the mass of reactants used?

 

[Metanoia]

Is the mass of total products always equal to the mass of reactants used?

Yes, that's right. Conservation of mass.

 

[The Sarcastic Retard]

Q15 how u find total mass?

1000 + 200

 

[forest822]

Water is added to anhydrous aluminium chloride to make a 0.1 mol dm-3 solution.
Which observations are correct?
1 The reaction is endothermic.
Why this statement is incorrect?

 

[The Sarcastic Retard]

Water is added to anhydrous aluminium chloride to make a 0.1 mol dm-3 solution.
Which observations are correct?
1 The reaction is endothermic.
Why this statement is incorrect?

Enthalpy change of hydration is always exothermic, not sure, but till now I have not come up with a question of it with Endothermic. If u know some reaction that is endothermic do lemme know!! Thanks.

 

[forest822]

Enthalpy change of hydration is always exothermic, not sure, but till now I have not come up with a question of it with Endothermic. If u know some reaction that is endothermic do lemme know!! Thanks.

Why this is enthalpy change of hydration instead of enthalpy change of solution? Thank you !

 

[The Sarcastic Retard]

Why this is enthalpy change of hydration instead of enthalpy change of solution? Thank you !

Both are different.

 

[SadiaMaryam]

Why this is enthalpy change of hydration instead of enthalpy change of solution? Thank you !

enthalpy of change hydration is the enthalpy change when "gaseous atoms" dissolve in water while enthalpy of solution is when "ionic compound' dissolves in water.. u can check whats going in your question and relate.

 

[The Sarcastic Retard]

Why this is enthalpy change of hydration instead of enthalpy change of solution? Thank you !

Here its the SEC of hydration of anhydrous salt.

 

[awesomaholic101]

can someone plz explain the 37th one?

 

[The Sarcastic Retard]

View attachment 57387
can someone plz explain the 37th one?

I was not aware of this thing till this paper came. That was a guess of mine and hopefully it was correct.
Connecting carbon should be sp^2 hybrydised. So, 1 and 2 are Sp2 but 3 is sp3.

 

[SadiaMaryam]

View attachment 57387
can someone plz explain the 37th one?

there is no free rotation around carbon to carbon double bond and therefore structures with c to c double bonds lie in the same plane...the third one does not have carbon to carbon double bond in the labelled carbons, the double bond shown is with O

 

[manya]

help plz
this is a paper 5 question, that means no application booklet, so how am i supposed to write the equation without it

 

[Sinzzzz]

hey!!
can someone please explain this:
When a sample of HI is warmed to a particular temperature the equilibrium below is established.
2HI(g) H2(g) + I2(g)
At this temperature, it is found that the partial pressure of HI(g) is 28 times the partial pressure of H2(g). What is the value of Kp at this temperature?
A 1.28 × 10–3
B 0.035
C 28
D 784
The answer is A.
Thank you!!

 

[The Sarcastic Retard]

hey!!
can someone please explain this:
When a sample of HI is warmed to a particular temperature the equilibrium below is established.
2HI(g) H2(g) + I2(g)
At this temperature, it is found that the partial pressure of HI(g) is 28 times the partial pressure of H2(g). What is the value of Kp at this temperature?
A 1.28 × 10–3
B 0.035
C 28
D 784
The answer is A.
Thank you!!

P^2(HI) = (28)^2
P(H2) = 1
P(I2) = 1
Kp = P(H2).P(I2) / P^2(HI)
Kp = A