40 Days of Chem - 9.4.1 = Part 1

9.4.1 HSC Questions

2001 Q25 - Generally well answered but make sure you include:
* NOX is produced in all combustion engines - even with  optimal fuel:air ratios - however if there is excess air (oxygen) then the production of NOX increases.
* If you are going to present a combustion equation  -make sure it is BALANCED!
* Note that complete combustion also gives optimal energy output & fuel efficiency
* Actually say that insufficient oxygen causes incomplete combustion  - this was overlooked in a few of your answers
* Finally - to answer the Q - you must say why you need to monitor the products - ie by monitoring what chemicals are produced in the exhaust the conditions of combustion can be altered to add more oxygen (If C and CO are produced) or less oxygen (if excessive NOX produced) and thus increase fuel effieicncy and decrease pollution.

2012 Q33  - Generally well answered but make sure you include:

* The correct cell chemistry and reactions - this will always lose marks
* That the dry and silver cells are non-rechargeable and thus contribute to bulk landfill
* A full ASSESSMENT ie introduction to the chemistry and chemicals of the cell, positives of collaborating,  consequences of not collaborating (-ves?) and a clear judgement at the end - even labelling it'judgement' is a good idea so the marker won't miss it.
* Actually say specifically what the chemists who are collaborating do - don't waffle - just get to the point eg. Analytical chemists might analyse the soil and rivers near the rubbish tip to determine the concentration of (Zn - using AAS? and H+ - using a probe), they would communicate this with Environmental Chemists who would investigate the impact of these concentrations. They both might need to collaborate with Research chemists to determine a way to halt the spread of pollution. The research chemist may collaborate with industrial chemists to determine new ways of producing or packaging or recycling the cell. Electro-chemists would be involved in any research to manufacture new cells which are less harmful and rechargeable...

Yellow is a Creative Colour

VSauce actually has some good stuff mixed into its videos (but sometimes tries to do too much) – this video below a good example (VERY good for Physics 9.4.1 TV’s) – and it shows how yellow IS a creative colour

BUT before you watch – make sure you have the chance to play the game associated with the picture below(the video gives it away without you having the fun of figuring it out)

Some of you may have seen it already but if you haven’t it is an interesting challenge. The picture shows images of eight sets of famous 'objects'– built from Lego in a very minimalist way. The fun is figuring out what they are!

Hence have a go before watching he video (BTW the 6th one is a little obscure – maybe especially so for your generation – and the 5th one is from a VERY obscure/foreign source (I had no idea))

 

& a LOL moment