This discussion is now closed.

Check out other Related discussions

OCR Chemistry F322~ 4th June 2013~ AS Chemistry

there's just one thing if some one could clear it up for me i would be soooooo grateful
so if you're doing bond enthalpy calculations do you do reactants - products?

Yeah, always.

Reply 2461

X44

2

Original post by SAS18

there's just one thing if some one could clear it up for me i would be soooooo grateful
so if you're doing bond enthalpy calculations do you do reactants - products?

Sum of B.E of Reactant minus that of the products

Posted from TSR Mobile

Reply 2462

SAS18

10

Original post by thefootyking19

yeah, always.

Original post by x44

sum of b.e of reactant minus that of the products

posted from tsr mobile

thank you so much!!!!

Reply 2463

iamvick

2

Original post by wndms

You need to know primary secondary tertiary halogenoalkanes. It was in the past paper

Posted from TSR Mobile

You need to know bout primary, secondary and tertiary alcohols. If something did come up about halogenoalkanes then it was simply testing you to use your knowledge of alcohols and apply it to halogenoalkanes.

It's going to be a similar principle - just look at how many carbons are attached the carbon with the halogen on it. A single carbon means primary, 2 carbons mean secondary and 3 carbons means tertiary.

Reply 2464

bry086

Original post by MBee

This is an afternoon exam right?
I always worry it's actually in the morn

Yeah definitely in afternoon :smile:

Posted from TSR Mobile

Reply 2465

_Ddraig_

19

Exam this afternoon :albertein:

Good luck to everybody :smile:

Reply 2466

QuantumSuicide

I thought enthalpy change of formation is products - reactants??

Posted from TSR Mobile

Reply 2467

ReginaPhalange29

When you do reactants - products, do you add a - sign to products prior to this?

So it's reactants - - products?

Posted from TSR Mobile

Reply 2468

Sam_1996

When do we use the structural formula for a compound(if it doesn't specify)

Reply 2469

Daisymydarling

2

Original post by QuantumSuicide

I thought enthalpy change of formation is products - reactants??

Posted from TSR Mobile

It is. But bond enthalpy and combustion are both reversed

Posted from TSR Mobile

Reply 2470

wndms

1

Q. Compare the efficiency of making ethanol eith rither fermentation or hydration of ethene.
Anyone help?

Posted from TSR Mobile

Reply 2471

Daisymydarling

2

Original post by Sam_1996

When do we use the structural formula for a compound(if it doesn't specify)

If it doesn't specify they usually allow all types of formulae. If your not sure, just use the structural one as it is the safest.

Posted from TSR Mobile

Reply 2472

bry086

If it doesnt specify what formula you can use any the mark schemes just often use the structural one

If it asks for molecular formula of alcohol do you write the OH separately?

Posted from TSR Mobile

Reply 2473

wndms

1

Original post by bry086

If it doesnt specify what formula you can use any the mark schemes just often use the structural one

If it asks for molecular formula of alcohol do you write the OH separately?

Posted from TSR Mobile

My teacher said use molecular unless stated structural

Posted from TSR Mobile

Reply 2474

GeneralOJB

Original post by bry086

If it doesnt specify what formula you can use any the mark schemes just often use the structural one

If it asks for molecular formula of alcohol do you write the OH separately?

Posted from TSR Mobile

No, you will lose marks for that. Alcohols must be written ex. C2H6O

Reply 2475

Lagukage4

Original post by bry086

If it doesnt specify what formula you can use any the mark schemes just often use the structural one

If it asks for molecular formula of alcohol do you write the OH separately?

Posted from TSR Mobile

if they specifically ask for molecular formula, you cant write OH at the end :smile:

so for example C3H8O is correct molecular formula :smile:

Reply 2476

GeneralOJB

Original post by wndms

My teacher said use molecular unless stated structural

Posted from TSR Mobile

You can lose marks for that too. When writing equations with alcohols/carboxylic acids/aldehydes etc. in it you should write it structural. They can penalise you if you use C2H6O in an equation instead of C2H5OH.

Reply 2477

Lagukage4

right well good luck everyone! just remember, even if it is a little tough, grade boundaries will be low so chances are you'll still get a good grade :biggrin:

Reply 2478

wndms

1

Original post by GeneralOJB

You can lose marks for that too. When writing equations with alcohols/carboxylic acids/aldehydes etc. in it you should write it structural. They can penalise you if you use C2H6O in an equation instead of C2H5OH.

Thank you!

Posted from TSR Mobile

Reply 2479

Dejir

What is heterogeneous catalyst

OCR Chemistry F322~ 4th June 2013~ AS Chemistry

Related discussions

Latest

Trending

Trending

Articles for you