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AQA Chemistry C3 - Unofficial Mark Scheme

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Reply 80

Fr3dg

Original post by arj2104

Thanks! I believe you get 1 mark for the Correct temperature (Delta Theta)
1 mark for rearranging the equation
1 mark for the right answer

You don't rearrange the equation though, I think it'd one for correct things used in equation, one for using equation, one for result.

Reply 81

Roquebrune2014

Original post by 1jonam16

i misread the units and put -1.276 becos i divided by 1000 at the end; will i lose only 1 mark or all 3?

Probably will lose 2, so will get 1/3

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Reply 82

Fr3dg

Only one since the method was correct

Original post by 1jonam16

i misread the units and put -1.276 becos i divided by 1000 at the end; will i lose only 1 mark or all 3?

Reply 83

JKING>)

Original post by 1jonam16

are you dumb? How does hydrogencarbonate decompose to calcium ions. It decomposes to carbonate ions, get lost and stop making rubbish mark shcemes.

Stop ****ing crying. Be happy that he actually had the effort to make a mark scheme.

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Reply 84

sunny181113

Original post by TheAnon121

For specific heat capacity, I got 3444J. And some people said it was F for that and some Rb - not sure which one was right

I worked out 3444 but stupidly divided it by 0.8, I'll only lose one mark right??

Reply 85

1jonam16

Original post by JustasB

Stop ****ing crying. Be happy that he actually had the effort to make a mark scheme.

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oh the irony.

Reply 86

mrtum3000

Original post by TheAnon121

Post your answers below, and we'll get an unofficial mark scheme!

Random answers:
Bond energies: -1276
Explain why: Energy needed making bonds was greater than energy released breaking bonds
Balance equation: 2 and 2 somewhere
Efficiency of Kettle: Hydrogencarbonate ions thermally decompose to calcium ions, then react with carbon to product a precitipates of calcium carbonate (limescale). Limescale is a bad conductor of electricity - more energy needed to heat water
Hard water cleaner q: Calcium and magnesium ions replaced by sodium and hydrogen ions
Benefits of hard water: contains calcium which strengthens teeth and bones
Element that has low boiling point: F
What happens in the mixture of gases? Ammonia is liquified, then cooled - Nitrogen and Hydrogen are recycled
Specific heat capacity: 3444J
How is methane obtained: Cows (?)
Two boiling tubes: Tube A: fizzing because acid is dissolving calcium carbonate
Tube B: calcium carbonate produced, solution goes cloudy

Corrections:
''Tube B: calcium carbonate produced, solution goes cloudy'' - carbon dioxide makes limewater go cloudy
''How is methane obtained: Cows (?)'' - natural gas
''Element that has low boiling point: F'' - Rb is also valid I think

Reply 87

rileypa

Original post by Roquebrune2014

So did I is -1276 wrong?

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Yh. They said that it was endothermic therefore it is a positive number.

Reply 88

Kyle03

Original post by Sadxa

So what is the answer? 4305 or 3444?

Are you referring to the hydrocarbon fuel question? If so all I did was find the energy released of 1g of each fuel then compared.

Reply 89

Zuzuriri

It was a acid catalyst for esters and test tube 1 was I said the solution fizzes and produces bubbles as the calcium carbonate decomposes and test tube 2 the limewater turns cloudy because carbon dioxide gas is present/added

Reply 90

1jonam16

Original post by Roquebrune2014

Probably will lose 2, so will get 1/3

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Original post by Fr3dg

Only one since the method was correct

so how many marks? 1 or 2? i calculated the energy released and then absorbed and got -1276 J, hence all along i wrote Joules and then converted at the end to KJ rather than using KJ all along (stupid misreading) thanks tho

What was the question about specific heat capacity?

Reply 93

Wimsett

Original post by rileypa

Yh. They said that it was endothermic therefore it is a positive number.

No that answer is right, the next question said it was exothermic

Reply 94

Dat1Guy

Original post by user2k16

the bond energy question I didn't get a minus (-) as it wuas an endothermic reaction ?

Yes that's right, it has to be positive for endothermic reaction

Reply 95

Wimsett

I forgot to write sulphuric acid but just wrote sulfur for the catalyst question, would this be valid ?

Reply 96

Roquebrune2014

Original post by rileypa

Yh. They said that it was endothermic therefore it is a positive number.

It quite clearly said exothermic

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Reply 97

ituneserror

Can someone tell me the question for the specific heat capacity?

Reply 98

Fr3dg

Original post by 1jonam16

are you dumb? How does hydrogencarbonate decompose to calcium ions. It decomposes to carbonate ions, get lost and stop making rubbish mark shcemes.

are you dumb? it decomposes to carbonate ions and water and carbon dioxide, along with a metal ion if was bonded to that originally, for example calcium, since before being ionized, the hydrogencarbonate ion is usually ionically bonded to calcium, forming the salt, calcium hydrogen carbonate, get lost and stop making rubbish responses to people who are putting in effort to help other people