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B (Salters) F331 (Chemistry for Life) 22nd May 2015 [Official Thread]

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But part 2 confirmed that the reaction produced heat so it had to be exothermic, so I put my value as negative (can't remember what it was)

I put -196

Reply 121

ZoeWoah

Original post by DominoMatrix227

Was the actual bond angle greater or smaller than the predicted?

I put smaller

Reply 122

shooting_stars

Original post by DominoMatrix227

Was the actual bond angle greater or smaller than the predicted?

Smaller.. predicted was 109 and actual is 60 (you can kind of imagine it like a equilateral triangle)

Reply 123

DominoMatrix227

Same here, was the compound anything other than three carbons?

Reply 124

TheAstrocist

What did everyone put for the 3 stages of the mass spectrometer?

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Reply 125

Florenceycl

For the enthalpy change dont we have to divide it by two as its asking for standard enthalpy that has to be one mole?

Reply 126

shooting_stars

Original post by TheAstrocist

What did everyone put for the 3 stages of the mass spectrometer?

Posted from TSR Mobile

ionisation
acceleration
drift region

Reply 127

ZoeWoah

Original post by shooting_stars

I put -196

So do I, minusing the products from the reactant produced a positive but I assumed because it gave out heat it had to be negative

Reply 128

Bobhopkins05

For the Hess law calculation I got -196 but divided it by 2 (because there were two moles but the units are per 1 mole)
Is that wrong
Will I get at least one mark?
I actually put down -196 then changed it because I thought it was a trap and you had to divide by two
Was the questions enthalpy change of combustion or formation?

Reply 129

DominoMatrix227

Original post by TheAstrocist

What did everyone put for the 3 stages of the mass spectrometer?

Posted from TSR Mobile

Ionisation
Acceleration
Drift region

PS: I'm not sure if you were meant to say acceleration to same Ek but I included it somewhere in the next point

Reply 130

ZoeWoah

Original post by shooting_stars

Smaller.. predicted was 109 and actual is 60 (you can kind of imagine it like a equilateral triangle)

Did it ask to give the predicted value or actual?

Reply 131

shooting_stars

Original post by ZoeWoah

Did it ask to give the predicted value or actual?

Both

Reply 132

TheAstrocist

Original post by DominoMatrix227

Ionisation
Acceleration
Drift region

PS: I'm not sure if you were meant to say acceleration to same Ek but I included it somewhere in the next point

Original post by shooting_stars

ionisation
acceleration
drift region

Great, was unsure about that question

Reply 133

DominoMatrix227

For the 3 marker (Mass spectrometry) I put:

Ionisation by removing electrons (so ions are affected by a negative field)
Acceleration to same Ek
Heavier ions/isotopes take longer to reach the detector

Reply 134

ZoeWoah

Original post by shooting_stars

Both

I said predicted would be 109 but actual would be smaller, would i get the marks? :/

Reply 135

f.loco

Q1:
Mass of e: v.small
The others are basic

Ionisation
Acceleration
Drift region

Mass spec, same Ek given to each particle heavier reach later than lighter which is detected by detector and form mass spec graph

Left gaps so it fits the same patterns

Beta decay was Se + 2e

Vol of gas: 277.2/8

Ar of Ge: 72.7

Ion in end: SiO3^2-

Bonding is ionic

Cloudy as co2 forms precipitate

NO2 as high temp and pressyre by engine creates right conditions for O2 and N2 to form bonds

Reforming
Hydrogen

Purpose of catalyst to speed up reaction

2 variables: same mass of metals
Sams heating time

-196kJmol^-1

Bond angle: 109° but actual 104° as corners squeeze the electron clouds.

Emision spec: descrete E level, e- absorb photon. Excited to higher shell. When return to geound state release photon of characteristic frequency eqaual to E/h. Diff spec for diff elements as diff electron arrangement

Theres some answers i put down

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Reply 136

damdar98

Original post by Marli-Ruth

Me!

277.9!!!

Reply 137

DominoMatrix227

How did everyone do that half life question? I took 3 values (all different) and took an average to get 2.0x10something.

Reply 138

m.chloe

Original post by TheAstrocist

Great, was unsure about that question

for the second stage my mind went completely blank...but I put 'electric field, ions have same kinetic energy'...completely forgot about acceleration..would I still get the mark? :/