Chemistry: Post your doubts here!

[Saad the Paki]

Hello, can somebody please help me solve these questions?

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Thanks in advance.

For the first question:

10cm3 of CS2 will burn in 30cm2 of O2 to give 10 cm3 of CO2 and 20 cm3 of SO2 (basic stoichiometry) . But we have 50cm3 of O2 which means it's an excess. 50-30=20cm3 of excess O2. So after burning out total volume will be :
10cm3 of CO2 + 20cm3 of SO2 + 20cm3 of leftover O2 = 50cm3 of gas.
When these gases are passed through NaOH which is basic, it will react with acidic gases and absorb them
CO2 and SO2 are acidic whereas O2 is neutral. So NaOH will absorb 10cm3 of CO2 + 20cm3 of SO2= 30cm3 absorbed. So leftover volume will be Total-absorbed = 50-30= 20cm3. Which makes option C correct.

 

[Thought blocker]

Hello, can somebody please help me solve these questions?

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Thanks in advance.

 

[Bah...]

For the first question:

10cm3 of CS2 will burn in 30cm2 of O2 to give 10 cm3 of CO2 and 20 cm3 of SO2 (basic stoichiometry) . But we have 50cm3 of O2 which means it's an excess. 50-30=20cm3 of excess O2. So after burning out total volume will be :
10cm3 of CO2 + 20cm3 of SO2 + 20cm3 of leftover O2 = 50cm3 of gas.
When these gases are passed through NaOH which is basic, it will react with acidic gases and absorb them
CO2 and SO2 are acidic whereas O2 is neutral. So NaOH will absorb 10cm3 of CO2 + 20cm3 of SO2= 30cm3 absorbed. So leftover volume will be Total-absorbed = 50-30= 20cm3. Which makes option C correct.

Thank you!

 

[Bah...]

Thank you!

 

[Rameen19]

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

 

[Atharxd1]

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!

 

[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