OCR Gateway Chemistry C4C5C6 - 13/06/13

Scroll to see replies

Reply 60

Red Fox

Original post by ryanb97

well its a module from MIT .. or Harvard.. i think it will be worth something

oh and its

Spoiler

No need for the sarcasm :rolleyes:

, I've just started the MIT Mechanics one.

Reply 61

TanyaB21

Did I misclick on the Physics discussion thread instead of the chemistry one?

Reply 62

L'Evil Fish

Original post by IHTWFR

Did I misclick on the Physics discussion thread instead of the chemistry one?

?? This is chem... Link to physics is on first post.

Reply 63

BP_Tranquility

I wonder if this is good for chemistry revision :tongue:

-
[video="youtube;ljvX-RMv_lw"]http://www.youtube.com/watch?v=ljvX-RMv_lw[/video]

Reply 64

BP_Tranquility

Good YouTube channel for chemistry (OCR Gateway); it covers C4/C5/C6! :biggrin:

http://www.youtube.com/user/GCSEChemistryTeacher/videos

Reply 65

L'Evil Fish

Original post by BP_Tranquility

Good YouTube channel for chemistry (OCR Gateway); it covers C4/C5/C6! :biggrin:

http://www.youtube.com/user/GCSEChemistryTeacher/videos

Looks great!

Reply 66

AR-13

Any one know how to tackle the six markers?

Posted from TSR Mobile

Reply 67

BP_Tranquility

Which of these revision guides (equations for CFCs) is correct? Because both seem to make sense to me... :smile:

ImageUploadedByStudent Room1370602070.784879.jpg

ImageUploadedByStudent Room1370602079.801300.jpg

Posted from TSR Mobile

Reply 68

Elcor

Original post by BP_Tranquility

Which of these revision guides (equations for CFCs) is correct? Because both seem to make sense to me... :smile:

Posted from TSR Mobile

They're both right because different reactions can happen when it comes to CFCs. I would learn the CGP one.

Reply 69

Elcor

Original post by AR-13

Any one know how to tackle the six markers?

Posted from TSR Mobile

Make sure you make 6 points, explain each one if it asks you to. Use proper scientific terminology.

Reply 70

DeadUnicorn

Do you guys think the controlled assessment grade boundaries will go lower, cause everyone seems to have found them hard :confused:

Reply 71

BP_Tranquility

Scenario:
I do a titration and get the following readings (on how much alkali was needed to neutralise an acid):

Rough titration: 24.5cm³
Experiment 1: 25.7cm³
Experiment 2: 24.4cm³
Experiment 3: 25.4cm³

And I want to find the average using the 3 most consistent results- which of these 3 results do I use? Do I use the rough titration value since it's consistent with titrations 2 and 3, or do I ignore this value since it wasn't a proper titration (and just a rough one)? :smile:

Reply 72

Elcor

Original post by BP_Tranquility

I wouldn't - to quote my revision guide:

"The first titration you do should be a rough titration to get an approximate idea of where solution changes colour. You then need to repeat it a few times, making sure you get the same answer each time within 0.2 cm^3"

I would actually ignore experiment 2's result as well, it looks anomalous as far as the 'within 0.2 cm^3' thing goes.

Reply 73

BP_Tranquility

Original post by andersson

Okay, what if it was this :tongue:

:

Rough titration: 24.5cm³
Experiment 1: 24.6cm³
Experiment 2: 24.4cm³
Experiment 3: 24.4cm³
Experiment 4: 24.7cm³

Which 3 most consistent results would you use? :smile:

Reply 74

Elcor

Original post by BP_Tranquility

Okay, what if it was this :tongue:

:

Rough titration: 24.5cm³
Experiment 1: 24.6cm³
Experiment 2: 24.4cm³
Experiment 3: 24.4cm³
Experiment 4: 24.7cm³

Which 3 most consistent results would you use? :smile:

1, 2 and 3. I still wouldn't use the rough titration because, after all, it's 'rough'. Even though it's 0.1mL closer to experiment 2 and 3's data than experiment 1, the rough titration is less reliable since you're pretty much just pouring one substance into the other and seeing where abouts it neutralises.

Obviously I'm no scientist, but that's what I would do. :redface: