Chemistry: Post your doubts here!

[Thought blocker]

Chemistry periodicity, group 2 & group 17 equations.. How do we memorize so many? Advice would be appreciated thankyou

Write it down in a piece of a chart paper, with colorful sketchpens as mind can capture colorful things much faster, stick it somewhere where u will look at that place frequently memorise them when u go to sleep and try to make that chart picture in ur head n try to memorize like that

 

[drowning-in-studies]

9 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
How to do this?

 

[Thought blocker]

9 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
How to do this?

A?

 

[Thought blocker]

Hey everybody i'm new around here. In currently in AS after failing first year IB (sad story, but it is the story). Now i'm stuck in one AS question:

Ferrochrome is an alloy of iron and chromium. Ferrochrome can be dissolved in dilute sulfuric acid to produce a mixture of FeSO4 and Cr2(SO4)3. The FeSO4 reacts with K2Cr2O7 in acid solution according to the following equation. 14H+ + 6Fe2+ + Cr2O72– → 2Cr3+ + 6Fe3+ + 7H2O When 1.00 g of ferrochrome is dissolved in dilute sulfuric acid, and the resulting solution titrated, 13.1 cm3 of 0.100 mol dm–3 K2Cr2O7 is required for complete reaction. What is the percentage by mass of Fe in the sample of ferrochrome?

A 1.22
B 4.39
C 12.2
D 43.9
Could anyone explain to me with steps, also showing the working to get to the final answer, THANKS!

D?

 

[Mohit Bhandari]

Plss help me friends !!!

 

[Mohit Bhandari]

Pls help me friends!!!

 

[abhisheksinghrajput]

bhai main patanjali use karta hu mera toh sab natural h

 

[drowning-in-studies]

A?

It is A. But how did you get that?

 

[Thought blocker]

It is A. But how did you get that?

Kp = 1^2/(28)^2

 

[Thought blocker]

Pls help me friends!!!

Anhydrous AlCl3 + C12H25Cl

 

[i_try9621]

hey can anyone recommend me a good coursebook for AS and A level ?

 

[Thought blocker]

hey can anyone recommend me a good coursebook for AS and A level ?

 

[drowning-in-studies]

5 Given the following enthalpy changes,
I2(g) + 3Cl2(g) → 2ICl3(s) ∆Ho = –214kJ mol–1
I2(s) → I2(g) ∆Ho = +38kJ mol–1
What is the standard enthalpy change of formation of iodine trichloride, ICl3(s)?
A +176kJ mol–1 B –88kJ mol–1 C –176kJ mol–1 D –214kJ mol–1

Can someone help me on how to generally approach these kind of enthalpy questions?
Do you draw the reactants, products, elements cycle
or what?? im really confused
The ans is B

 

[Thought blocker]

5 Given the following enthalpy changes,
I2(g) + 3Cl2(g) → 2ICl3(s) ∆Ho = –214kJ mol–1
I2(s) → I2(g) ∆Ho = +38kJ mol–1
What is the standard enthalpy change of formation of iodine trichloride, ICl3(s)?
A +176kJ mol–1 B –88kJ mol–1 C –176kJ mol–1 D –214kJ mol–1

Can someone help me on how to generally approach these kind of enthalpy questions?
Do you draw the reactants, products, elements cycle
or what?? im really confused
The ans is B

-214+38 * o.5

 

[drowning-in-studies]

The standard enthalpy change for the reaction
2NF3(g) → 2N(g) + 6F(g) is ∆Ho = +1668kJ
What is the bond energy of the N–F bond?
A –556kJ mol–1 B –278kJ mol–1 C +278kJ mol–1 D +556kJ mol–1
Ans is C...but im getting D -_-

 

[Thought blocker]

The standard enthalpy change for the reaction
2NF3(g) → 2N(g) + 6F(g) is ∆Ho = +1668kJ
What is the bond energy of the N–F bond?
A –556kJ mol–1 B –278kJ mol–1 C +278kJ mol–1 D +556kJ mol–1
Ans is C...but im getting D -_-

1668 / (3 * 2)

 

[drowning-in-studies]

1668 / (3 * 2)

Ohh... That's it?
I did the bonds broken-bonds formed

 

[Thought blocker]

Ohh... That's it?
I did the bonds broken-bonds formed

but y?
this was very simple

 

[drowning-in-studies]

but y?
this was very simple

Now its easy

 

[drowning-in-studies]

10.When solid ammonium chloride dissociates at a certain temperature in a 0.500 dm3 container,
ammonia and hydrogen chloride are formed.
NH4Cl (s) NH3(g) + HCl (g)
The initial amount of ammonium chloride was 1.00 mol, and when the system had reached
equilibrium there was 0.300 mol of ammonium chloride.
What is the numerical value of Kc for this reaction under these conditions?
A 0.490 B 1.63 C 1.96 D 3.27
ans is C But how do we get that?