VCE Chemistry Question Thread

[Quantum44]

Wheres everyone up to in chemistry currently? My school has finished chapter 8 and onto 9 with a sac next week on chapter 8 and a sac after that on 9

Doing the Heinemann textbook:

Done 1-8 and had both Unit 3 SACs, however we are still working on chapter 9 and I think we are going to do the poster SAC on electrolysis (chapter 9), so hopefully starting Unit 4 soonish.

[pmmenotes]

Can someone explain this extent of reaction business in equilibrium? really confusing me

[pmmenotes]

when drawing a exothermic graph does the products increase and the reactants decrease?

equation is Fe^3+(aq) + SCN^-(aq)--><--Fe(SCN)^2+(aq)

- this is from an experiement also where one testtube of Fe(SCN)2+ solution was placed in ice cold water and the other in 'boiling' water, trying to draw the graph for this. (time/concentration graph)

[Quantum44]

when drawing a exothermic graph does the products increase and the reactants decrease?

equation is Fe^3+(aq) + SCN^-(aq)--><--Fe(SCN)^2+(aq)

- this is from an experiement also where one testtube of Fe(SCN)2+ solution was placed in ice cold water and the other in 'boiling' water, trying to draw the graph for this. (time/concentration graph)

Since the forward reaction is exothermic, placing the equilibrium system in ice cold water will favour the forward reaction (products) as the system will partially oppose the change by increasing the temperature. Placing the equilibrium system in boiling water will favour the back reaction (reactants) as the system will partially oppose the change by decreasing the temperature.

So for cold water the products increase and reactants decrease and for hot water the products decrease and reactants increase.

[shezz.iazz]

I have recently done a Chemistry Test in which there was the following question;
   - A molecule of CO2 is shown

Q1.) How many non-bonding electrons does this molecule have?
         My answer: 4 non-bonding Pairs

Q2.) How many bonding electrons does this molecule have?
         My answer: 4 bonding pairs of electrons

The teacher only gave me half mark for each and said the right answer was: "8 electrons for Q1 and 8 electrons for Q2". Was I suppose to get full marks as 4 pairs of electrons in scientific terms does mean 8 electrons?

[Shadowxo]

I have recently done a Chemistry Test in which there was the following question;
   - A molecule of CO2 is shown

Q1.) How many non-bonding electrons does this molecule have?
         My answer: 4 non-bonding Pairs

Q2.) How many bonding electrons does this molecule have?
         My answer: 4 bonding pairs of electrons

The teacher only gave me half mark for each and said the right answer was: "8 electrons for Q1 and 8 electrons for Q2". Was I suppose to get full marks as 4 pairs of electrons in scientific terms does mean 8 electrons?

If they asked the number of electrons, you should answer in terms of electrons instead of electron pairs. That being said though, I think deducting marks is a bit harsh but you had the right idea

[littlemouse397]

Has anyone done their equilibrium sac yet? or know where I can get some questions or papers to do? In need baadd

[Syedali_]

Chapter 8 review Question 29 c)
Chemistry Heinemann
 

[Syedali_]

Attachment to question

[zxcvbnm18]

Effective ways to study for chem? 

[Quantum44]

Effective ways to study for chem? 

The best way to study for chem is write notes on the concepts and do practice questions on the more quantitative areas of the course. Then just see what you got wrong and add them to your notes so you don't make the same mistake again.

[zxcvbnm18]

The best way to study for chem is write notes on the concepts and do practice questions on the more quantitative areas of the course. Then just see what you got wrong and add them to your notes so you don't make the same mistake again.

Thnx I'll try. Nothing seems to be working at the moment

[Gogo14]

For electrolytic reactions that occur in solution, why can the half equations contain hydrogen ions as a reactant even though it is not present (or may present in water, at low concentrattiojs)?

[zxcvbnm18]

Difference between the reaction quotient and the equilibrium constant?

[Quantum44]

Difference between the reaction quotient and the equilibrium constant?

The reaction quotient is calculated using the same formula as the equilibrium constant, however it can be calculated using concentrations of products and reactants when the system is not at equilibrium.

For example if they give you the equilibrium constant and the concentrations of all species at an abitrary point in time (when the system is not at equilibrium), you can determine which way the reaction must shift to restore equilibrium using the reaction quotient.