who have answers to this book???(edexcel)

[Deadly_king]

my second question is is this Q1:definition write or should it include 1/12th the mass of carbon-12 atom

Q2: i have attatched the table and the question

if u know what are the studies that would be needed to determine if food labelling has an impact on dietary choices??

1. The definition is sometimes said to be enough but I'll advice you to always include the 1/12^th. This will make your answer more precise and you can be sure not to lose marks in case they take it as a key point.

2. (a) According to the table, the very high mass of CO in air is about 20 or more ppm within an average of 8 hours.

Since you're asked minimum, you should take 20. And since you need for 24 hours, juts multiply by 3.

Hence answer is (20 x 3) = 60 ppm

(b) As you can note from the table, each pollutant has its own lapse of time or is measured in either ppm or ppb. This pose a problem when you're going to compare the data.

Therefore you should convert all of them to the same lapse of time (Example : 24hr) and same unit.(Example : ppb)

Now to your question.

According to me food labelling indeed has an impact on dietary choices. But how can we determine that?

First you should have a certain number of persons who are on diet. Then you note all the substances that they buy after having consulted a doctor and considering his advice with utmost importance.

After that you list all the ingredients of these substances and compare what are present in high numbers and what is absent.

NOTE : The last answer is just my opinion about it. There may be various ways of proceeding.

[~ Miss Relina ~]

1. The definition is sometimes said to be enough but I'll advice you to always include the 1/12^th. This will make your answer more precise and you can be sure not to lose marks in case they take it as a key point.

2. (a) According to the table, the very high mass of CO in air is about 20 or more ppm within an average of 8 hours.

Since you're asked minimum, you should take 20. And since you need for 24 hours, juts multiply by 3.

Hence answer is (20 x 3) = 60 ppm

(b) As you can note from the table, each pollutant has its own lapse of time or is measured in either ppm or ppb. This pose a problem when you're going to compare the data.

Therefore you should convert all of them to the same lapse of time (Example : 24hr) and same unit.(Example : ppb)

Now to your question.

According to me food labelling indeed has an impact on dietary choices. But how can we determine that?

First you should have a certain number of persons who are on diet. Then you note all the substances that they buy after having consulted a doctor and considering his advice with utmost importance.

After that you list all the ingredients of these substances and compare what are present in high numbers and what is absent.

NOTE : The last answer is just my opinion about it. There may be various ways of proceeding.

Thanks very much I really appreciate ur help pal Thanks and I'll be waitng always for ur replies to me 

[~ Miss Relina ~]

first Q , my teacher said that it has to be compared to 1/12 of a carbon12 atom .

Second Q , sorry can't help u I'm doing something else 

ohno robs Thanks anyway 

[Deadly_king]

Thanks very much I really appreciate ur help pal Thanks and I'll be waitng always for ur replies to me 

You're welcome dear.

I'll be glad to help you as much as I can.

[The Golden Girl =D]

ohno robs Thanks anyway 

Hmm np =]

[~ Miss Relina ~]

me agaun that my questions and for question concerning calorimeter i have attatched the picture for (fig1.2.10)

[Deadly_king]

me agaun that my questions and for question concerning calorimeter i have attatched the picture for (fig1.2.10)

1st attachment. No 3

is exothermic since we can note from the graph that the products are at a lower temperature than the reactants. This means that they possess less energy. Therefore energy has been released during the reaction which demonstrates that the reaction is indeed exothermic.

is endothermic. Same principle as above is applied. I guess you'll be able to put n your own words.

Temperature change for A - exothermic : (30 - 10) = 20^oC
Temperature change for B - endothermic : (40 - 20) = 20^oC

4th attachment

You should use the two equations provided below to form the required equation which is :
H₂SO₄ + 2KCl -----> 2HCl + K₂SO₄

Now we need to re-arrange the information provided to get this. You need to inverse the 2nd equation provided and multiply it by 2.
H₂SO₄ + 2KOH ----> K₂SO₄ + 2H₂O    ^H = -324 KJ   
2KCl + 2H₂O ----> 2HCl + 2KOH     ^H = +408 KJ

NOTE : When you inverse an equation and multiply it by 2, you should inverse the enthalpy change as well and multiply it too.

Now you mix the two equations.
H₂SO₄ + 2KOH + 2KCl + 2H₂O ----> K₂SO₄ + 2H₂O + 2HCl + 2KOH

From this resulting equation you can note that 2KOH and 2H2O cancel each other from both sides of the equation.

So now you get your equation. For its enthalpy change you just need to add them tegether.
^ H = -324 + 408 = +84 KJ

[Deadly_king]

5th attachment

This is the equation representing the formation of propanoic acid.
3C + 3H₂ + 1/2O2 ----> C₃H₅OH

Since the enthalpy changes of combustion has been given to you, you also need to write the equation relating each substance and its respective combustion.
1. C + O₂ ----> CO₂  (Enthalpy change of formation of carbon dioxide)
2. H₂ + 0.5O₂ ----> H₂O (Enthalpy change of formation of water)
3. C₃H₅OH + 9/2O₂ ----> 3CO₂ + 3H₂O (Enthalpy change of combustion of propanoic acid)

As you may observe, the combustion of both hydrogen and carbon leads to carbon dioxide and hydrogen as well as the combustion of butane.

Hence, according to Hess's law, we may opt for another route in the conversion of carbon and hydrogen to butane.

Let's say we'll convert 3 moles of carbon and 3 moles of Hydrogen gas to carbon dioxide and water. Then these two products are converted to propanoic acid.

In practise these reactions are not feasible. But in theory we may opt for that method to find standard enthalpy changes of a particular reaction.

Let ^C be the enthalpy change of combustion of carbon.
So Enthalpy change of formation of propanoic acid = 3(^C) + 3(^H) - (^C₃H₅OH) = 3(-393.5) + 3(-285. - (-1527.2) = -510.7 KJ

NOTE : We need to subtract the enthalpy change of combustion since we are converting carbon dioxide and water back to propanoic acid whereas the enthalpy change of combustion of propanoic acid actually is the energy evolved when 1 mole of propanoic acid is completely burnt to carbon dioxide and water. In other words we are doing just the contrary, that's why we need to subtract it.

[~ Miss Relina ~]

5th attachment

This is the equation representing the formation of propanoic acid.
3C + 3H₂ + 1/2O2 ----> C₃H₅OH

Since the enthalpy changes of combustion has been given to you, you also need to write the equation relating each substance and its respective combustion.
1. C + O₂ ----> CO₂  (Enthalpy change of formation of carbon dioxide)
2. H₂ + 0.5O₂ ----> H₂O (Enthalpy change of formation of water)
3. C₃H₅OH + 9/2O₂ ----> 3CO₂ + 3H₂O (Enthalpy change of combustion of propanoic acid)

As you may observe, the combustion of both hydrogen and carbon leads to carbon dioxide and hydrogen as well as the combustion of butane.

Hence, according to Hess's law, we may opt for another route in the conversion of carbon and hydrogen to butane.

Let's say we'll convert 3 moles of carbon and 3 moles of Hydrogen gas to carbon dioxide and water. Then these two products are converted to propanoic acid.

In practise these reactions are not feasible. But in theory we may opt for that method to find standard enthalpy changes of a particular reaction.

Let ^C be the enthalpy change of combustion of carbon.
So Enthalpy change of formation of propanoic acid = 3(^C) + 3(^H) - (^C₃H₅OH) = 3(-393.5) + 3(-285. - (-1527.2) = -510.7 KJ

NOTE : We need to subtract the enthalpy change of combustion since we are converting carbon dioxide and water back to propanoic acid whereas the enthalpy change of combustion of propanoic acid actually is the energy evolved when 1 mole of propanoic acid is completely burnt to carbon dioxide and water. In other words we are doing just the contrary, that's why we need to subtract it.

Thanks alot I'll post other questions later

[Deadly_king]

Thanks alot I'll post other questions later

You're welcome.

[Vampire-Love4ever]

guys anybody who have answrs to chemistry book inthis link plz help
http://www.amazon.co.uk/Edexcel-Chemistry-Student-Level-Sciences/dp/1405896353
plz plz plz need it asap help as much as u can I have  exams soon     for edexcel

Answers are there in the CD.
Check the CD properly.
You'll find it

[~ Miss Relina ~]

Answers are there in the CD.
Check the CD properly.
You'll find it

i'm sure if u know how tell me   i need them v.. urgently...

[Helium]

Our class also wanted the answer's for that book,

just ask your teacher, they're found in the teacher guide of the book , so he

brought a copy of the anwsers, too bad he didn't give us a copy, so we ask him every time

he'll tell. simply just ask your teacher , by the way i think that book kinda sucks i give it 5.9/10.

[~ Miss Relina ~]

Our class also wanted the answer's for that book,

just ask your teacher, they're found in the teacher guide of the book , so he

brought a copy of the anwsers, too bad he didn't give us a copy, so we ask him every time

he'll tell. simply just ask your teacher , by the way i think that book kinda sucks i give it 5.9/10.

unfortunately, i am a private student so plz if u got them post them to me but also if u have got another book which is better tell me about it.

[The Golden Girl =D]

Well I suggest the CGP revision guide for Chemistry EDEXCEL exam board.

here :

AS-Level Chemistry
Exam board :Edexcel
The Revision Guide

ISBN 978 1 84762 124 5

It helped me A LOT =D