Chemistry: Post your doubts here!

[h4rriet]

Thanks

A number of alcohols with the formula C4
H10O are separately oxidised. Using 70g of the alcohols
a 62% yield of organic product is achieved.
What mass of product could be obtained?
1 42.2g of butanone
2 51.6g of butanoic acid
3 51.6g of 2-methyl propanoic acid

Find the molecular mass of butanone, butanoic acid and 2-methyl propanoic acid. Then find the yield using actual mass/calculated mass x 100. Choose the options whose yield = 62 %.

 

[magnesium]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_12.pdf
15,17 ?some1 HELP

 

[Alice123]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q4 h4rriet

 

[magnesium]

h4rriethttp://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_12.pdf
15,17 ?some1 HELP

 

[Dr.MMM]

i

Find the molecular mass of butanone, butanoic acid and 2-methyl propanoic acid. Then find the yield using actual mass/calculated mass x 100. Choose the options whose yield = 62 %.

m getting 58.6% for all of the three options, can you please solve any one option?

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Chemistry%20(9701)/9701_w12_qp_12.pdf
15,17 ?some1 HELP

15. In the equation for the decomposition of a Group II metal nitrate, the metal nitrate and the metal oxide have a mole ratio of 1:1. So (mass of nitrate)/(molecular mass of nitrate)=(mass of metal oxide)/(molecular mass of metal oxide). The mass of nitrate is given to be 2 grams. The mass of the metal oxide will 2 minus the mass of gas produced.
17. Find the moles of O2 from the information given. Write a balanced equation for the combustion of Ca and Mg. Then use mole ratios to determine whether the metal is Ca or Mg.

 

[h4rriet]

Thanks alot.
Could you please answer Q9 of this paper as well. And could you please work out the answer for all the options if its not a problem.
Thanks once again for ur time and effort.

9 is to be done the same way. Draw an ICE chart and add up the equilibrium moles.

 

[darkxangel]

Draw a Hess cycle.

Can you do it for me ?

 

[magnesium]

="h4rriet

q10 same ppr

 

[magnesium]

15. In the equation for the decomposition of a Group II metal nitrate, the metal nitrate and the metal oxide have a mole ratio of 1:1. So (mass of nitrate)/(molecular mass of nitrate)=(mass of metal oxide)/(molecular mass of metal oxide). The mass of nitrate is given to be 2 grams. The mass of the metal oxide will 2 minus the mass of gas produced.
17. Find the moles of O2 from the information given. Write a balanced equation for the combustion of Ca and Mg. Then use mole ratios to determine whether the metal is Ca or Mg.

q10 same ppr

 

[kiran11]

how shall we come to know which molecule has largest overall dipole as in Q10http://papers.xtremepapers.com/CIE/...20Level/Chemistry%20(9701)/9701_s12_qp_12.pdf

 

[Dr.MMM]

Find the molecular mass of butanone, butanoic acid and 2-methyl propanoic acid. Then find the yield using actual mass/calculated mass x 100. Choose the options whose yield = 62 %.

CAn you please solve one option for me, as im getting 58.6 for all three of them

 

[h4rriet]

CAn you please solve one option for me, as im getting 58.6 for all three of them

Sorry, I didn't read the question properly. It's to be done this way:

 

[Raiyan3]

Question number 7 please help
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s12_qp_12.pdf And question number 11 and 23
http://papers.xtremepapers.com/CIE/... AS Level/Chemistry (9701)/9701_s11_qp_12.pdf

 

[h4rriet]

how shall we come to know which molecule has largest overall dipole as in Q10http://papers.xtremepapers.com/CIE/...20Level/Chemistry%20(9701)/9701_s12_qp_12.pdf

In symmetrical molecules, dipoles cancel out.

 

[kiran11]

In symmetrical molecules, dipoles cancel out.

yes but how we will choose btwn C and B option of the same question?

 

[h4rriet]

Can you do it for me ?

Working on it.

 

[cute97]

16. This is something you have to memorise. Cl2 + cold, dilute NaOH will give a ClO- ion (oxidation state = +3) and Cl2 + hot, concentrated NaOH will give a ClO3- ion (oxidation state = +5).
20. Find the molecular masses of the products of propyl propanoate. The find the % by mass of each compound.
28. -NH2 from NH3 substitutes one Br atom. NH2 is a nucleophile too, and has to be close to the other C-Br bond so that it can attack it. 1,5 is closer than 1,4.

thank you here again Q20 same like the ques in previous paper plz explain one of them

 

[h4rriet]

yes but how we will choose btwn C and B option of the same question?

Can't see the question because your link doesn't work.

 

[h4rriet]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w11_qp_12.pdf
Q4 h4rriet

Construct the balanced equation for the reaction between N2 and H2. 120-96 kg of H2 is used. Use mole ratios.