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National 5 Chemistry

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Original post by SocialStudiesETC
Wouldn't mind a nuclear one, hard to go off it tbh if you put your brain to it! Yeah, first question is usually rate of reaction. I always make stupid mistakes on them admittedly


What do you think it would be about Nuclear radiation ? I dont have any general knowledge of examples etc, do I need to know that?
Out of curiosity, what did everyone get in their prelims?
I got 65 out of 80 (81%)
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Original post by SocialStudiesETC
Wouldn't mind a nuclear one, hard to go off it tbh if you put your brain to it! Yeah, first question is usually rate of reaction. I always make stupid mistakes on them admittedly


Me too sometimes
How do u know if an atom has lost or gained electrons so that you could write + or -
Original post by Ethan100
What do you think it would be about Nuclear radiation ? I dont have any general knowledge of examples etc, do I need to know that?


Well, I'd think about the ray lengths. Also, their effect on bodies and other relevant things mentioned. Their atmospheric life: I think gamma has the shortest and alpha has the longest. This is due to the structure of the particles emitted, with gamma rays having no photons. Why their use is useful compared to the other rays: for example, beta particles are used for medical imaging because they penetrate the skin but not the bones/organs.
Original post by Aston177
How do u know if an atom has lost or gained electrons so that you could write + or -


Assuming this is related to ionic formulae, metals LOSE ELECTRONS which give them a positive charge. Non-metals GAIN ELECTRONS which give them a negative charge. This is because of their positioning on the periodic table. Now, anything before group 4 loses electrons to achieve a stable outer shell. Group 4 gains electrons. Anything after group 4 gains electrons to fill their outer shell.
How to answer this sort of question?

Which of the following has metallic bonding?

A) Calcium
B) Carbon
C) Oxgyen
D) Fluorine
Does anybody use a triangle or something to help them with half life questions, I find them quite difficult
is there a formula for it that I can follow or something ?
Original post by Lewis H01
How to answer this sort of question?

Which of the following has metallic bonding?

A) Calcium
B) Carbon
C) Oxgyen
D) Fluorine


A as calcium is the only metal.
Oh and another thing, for the last part of chemistry in society I think its called Chemical Analysis, what do I need to know about it ? My class literally spent have a lesson on it and I don't know if it was enough
Original post by Ethan100
Does anybody use a triangle or something to help them with half life questions, I find them quite difficult
is there a formula for it that I can follow or something ?


So say if the half life of carbon is 5 years, in 5 years time there will be 50% left. in ten years time, there will be 25% left.

100%-----50%-----25%-----12.5%-----6.25% and so on
0 yrs -----5 yrs----10yrs-----15yrs-----20yrs

I hope that makes sense and I hope it is right!
Original post by Ethan100
Oh and another thing, for the last part of chemistry in society I think its called Chemical Analysis, what do I need to know about it ? My class literally spent have a lesson on it and I don't know if it was enough


That's like the titration calculations, flame tests, and if a precipitate is formed. So titre calcs are c1v1/n1 = c2v2/n2, flame tests are in the data book and the precip. is basically looking at the equation and seeing if a (s) has been formed.
Original post by eve_4342
So say if the half life of carbon is 5 years, in 5 years time there will be 50% left. in ten years time, there will be 25% left.

100%-----50%-----25%-----12.5%-----6.25% and so on
0 yrs -----5 yrs----10yrs-----15yrs-----20yrs

I hope that makes sense and I hope it is right!


THATS WHAT HALF LIFE MEANS :redface:
I WAS DOING IT WRONG ALL ALONG

THANKS SO MUCH EVE

Wait, what exactly is left ? The percentage is of what ?

THANKS !
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Original post by Ethan100
Does anybody use a triangle or something to help them with half life questions, I find them quite difficult
is there a formula for it that I can follow or something ?


There's no specific formula used for it. If you can give me an example of one of the questions, I can show you how to do them.
Original post by eve_4342
That's like the titration calculations, flame tests, and if a precipitate is formed. So titre calcs are c1v1/n1 = c2v2/n2, flame tests are in the data book and the precip. is basically looking at the equation and seeing if a (s) has been formed.


Does this stuff come up in the exam ....

You just spoke a completely different language there
Original post by Ethan100
Does this stuff come up in the exam ....

You just spoke a completely different language there


yep titration calculations have come up in both the 2014 and 2015 exams
Can someone tell me the main equations I need to know for neutralisation reactions?
Thanks, in advanced. :smile:
Original post by thomson521
yep titration calculations have come up in both the 2014 and 2015 exams


What is a titration calculation ? Would I be able to learn it now ?
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Original post by Lewis H01
Can someone tell me the main equations I need to know for neutralisation reactions?
Thanks, in advanced. :smile:


Metal + Acid = Salt + Hydrogen
Metal Oxide + Acid = Salt + Water
Metal Carbonate + Acid = Salt + Water + Carbon Dioxide
Metal Hydroxide + Acid = Salt + Water
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Original post by Ethan100
What is a titration calculation ? Would I be able to learn it now ?


Yes, they are very easy. The formula is in the data book

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