Chemistry: Post your doubts here!

[Xaptor16]

View attachment 51484

what is the answer to this?

 

[My Name]

what is the answer to this?

B

 

[shazmina]

View attachment 51482

can someone please help me with question 4?i know the equation is PV=nRT i just have problem finding the volume and the number of moles
the answer is A btw

First find out the volume of M using the initial conditions that have been provided using the formula PV=nRT
Where P= 1*10^5, V=?, T= ( 20+273 ) & n =1
so this way find out the volume ..... and u will get it as 0.024 m^3( i prefer u to the carry the entire answer in the calculator )
and then consider the entire system to find the new pressure which is found by using the same formula .. but this time u know the volume of N which is 3 times the volume of M therefore
New volume of the system = ( 4* 0.024 ) , New temp = ( 100 +273 ) & n = 1...
so this way u will get the new pressure as 3.18*10^4 Pa.. ie A
Hope you got it

 

[Xaptor16]

First find out the volume of M using the initial conditions that have been provided using the formula PV=nRT
Where P= 1*10^5, V=?, T= ( 20+273 ) & n =1
so this way find out the volume ..... and u will get it as 0.024 m^3( i prefer u to the carry the entire answer in the calculator )
and then consider the entire system to find the new pressure which is found by using the same formula .. but this time u know the volume of N which is 3 times the volume of M therefore
New volume of the system = ( 4* 0.024 ) , New temp = ( 100 +273 ) & n = 1...
so this way u will get the new pressure as 3.18*10^4 Pa.. ie A
Hope you got it

but are we just assuming that n=1?

 

[shazmina]

but are we just assuming that n=1?

yes

 

[Xaptor16]

yes

oh okay, thankyou! could you help me with this too, if possible please?
6 Use of the Data Booklet is relevant to this question. In some countries, anhydrous calcium chloride is used as a drying agent to reduce dampness in houses. The anhydrous salt absorbs enough water to form the dihydrate CaCl 2.2H2O. What is the percentage increase in mass?
A 14%
B 24%
C 32%
D 36%
answer is C

 

[Tasneem_m98]

Please help O/N/14 paper 13

8 Use of the Data Booklet is relevant to this 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

 

[Tasneem_m98]

Please help O/N/14 paper 13

8 Use of the Data Booklet is relevant to this 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

Thank you

 

[Tasneem_m98]

Please help O/N/14 paper 13

8 Use of the Data Booklet is relevant to this 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

Thank you

 

[Tasneem_m98]

Please help O/N/14 paper 13

8 Use of the Data Booklet is relevant to this 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

Thank you

 

[shazmina]

oh okay, thankyou! could you help me with this too, if possible please?
6 Use of the Data Booklet is relevant to this question. In some countries, anhydrous calcium chloride is used as a drying agent to reduce dampness in houses. The anhydrous salt absorbs enough water to form the dihydrate CaCl 2.2H2O. What is the percentage increase in mass?
A 14%
B 24%
C 32%
D 36%
answer is C

Your welcome
Well this is and easy question and it goes like this ...
First find the Mr of both the compounds .. i mean for CaCl2 ( 111.1g ) and for Cacl2.2H2O ( 147.1g ) .... and then find the increase in percentage using either using the cross multiplication method ( the method which i prefer all the time ) or any other way ....
(147.1*100)/111.1 = 132.4

therefore 132.4-100 = to get the increase in percentage from the standard 100%
which is 32 % .. ie C
Hope you got it ...

 

[shazmina]

The answer for this question is A
Can someone please explain me how compound A shows Methyl Methyl Propenoate ////

 

[The Chill Master]

In this case, we divide equally because the question gives us the information that "a single product was obtained after oxidizing."

We don't assume that we divide equally for all other questions unless the clues tells us so.

As for your example of 5 carbons, there is no way to obtain a single product after oxidizing.

Oh thanks a lot

 

[shazmina]

The Answer is D ...
Can someone please explain me why the answer is D and not C ?? please help ///

 

[shazmina]

http://onlineexamhelp.com/wp-content/uploads/2014/08/9701_s14_qp_11.pdf Question 29 of this paper ...
Can anyone please draw and show me all the possible Geometrical isomers that exist for that compound ....

 

[cool Hassan]

plz someone upload that page on which all AS level organic equation were there... its urgent plzz

 

[The Godfather]

The Answer is D ...
Can someone please explain me why the answer is D and not C ?? please help ///

The arrow is pointed towards water and from the cycle you can see there is 2 moles of water present. So 2 * delta H of H2O

 

[Xaptor16]

Your welcome
Well this is and easy question and it goes like this ...
First find the Mr of both the compounds .. i mean for CaCl2 ( 111.1g ) and for Cacl2.2H2O ( 147.1g ) .... and then find the increase in percentage using either using the cross multiplication method ( the method which i prefer all the time ) or any other way ....
(147.1*100)/111.1 = 132.4

therefore 132.4-100 = to get the increase in percentage from the standard 100%
which is 32 % .. ie C
Hope you got it ...

Thankyou so much! I realised what my mistake was, silly as always

 

[shazmina]

Thankyou so much! I realised what my mistake was, silly as always

You most welcome ah dw .. its just okay and now try to focus

 

[shazmina]

The arrow is pointed towards water and from the cycle you can see there is 2 moles of water present. So 2 * delta H of H2O

But may i know why is it +2???