Model an Equilibrium reaction (1 Viewer)

[invisible036]

Anyone can help me with an example to model an equilibrium reaction and identify risks as well as limitations ?

Thx for your help!

 

[sy37]

i)

2mL of 0.1M/L FeCL3 was mixed with 2mL of of 0.1M/L NH4SCN and diluted with distilled water to a volume of 20mL.
Fe3+(yellow) + SCN-(colourless) <--> FeSCN2+ (blood red). The initial colour was then recorded and the solution divided equally between 2 test tubes. Test tube one was placed in a hot water bath, test tube two was placed in an ice bath. By LCP, the ice bath shifted the equilibrium of this exothermic reaction to the right to turn the solution into a deeper red due to the presence of FeSCN2+ so as to counteract a decrease in temperature. Conversely, the hot water bath shifted the equilibrium to the left to favour the endothermic reaction and use more heat, making the solution a pale yellow (due to Fe3+).

ii) NH4SCN is a classified respiratory irritant, hence inhalation irritates the respiratory system.

iii) An equilibrium reaction is one in which the forward and reverse reactions have a tendency to change with disturbances. In our experiment, a hot and ice water bath were used to disturb the temperature. This allowed varying colour changes to occur in response to these disturbances as the reaction attempts to minimise these changes. A limitation of this model is that it is qualitative, hence was less accurate in determining a strict relationship

**For I, we added a bunch of other chemicals in the experiment but I kept it at temperature only here because it's only two marks.

***For III I'm not so sure if its a 3/3 exactly, someone confirm?

 

[invisible036]

i)

2mL of 0.1M/L FeCL3 was mixed with 2mL of of 0.1M/L NH4SCN and diluted with distilled water to a volume of 20mL.
Fe3+(yellow) + SCN-(colourless) <--> FeSCN2+ (blood red). The initial colour was then recorded and the solution divided equally between 2 test tubes. Test tube one was placed in a hot water bath, test tube two was placed in an ice bath. By LCP, the ice bath shifted the equilibrium of this exothermic reaction to the right to turn the solution into a deeper red due to the presence of FeSCN2+ so as to counteract a decrease in temperature. Conversely, the hot water bath shifted the equilibrium to the left to favour the endothermic reaction and use more heat, making the solution a pale yellow (due to Fe3+).

ii) NH4SCN is a classified respiratory irritant, hence inhalation irritates the respiratory system.

iii) An equilibrium reaction is one in which the forward and reverse reactions have a tendency to change with disturbances. In our experiment, a hot and ice water bath were used to disturb the temperature. This allowed varying colour changes to occur in response to these disturbances as the reaction attempts to minimise these changes. A limitation of this model is that it is qualitative, hence was less accurate in determining a strict relationship

**For I, we added a bunch of other chemicals in the experiment but I kept it at temperature only here because it's only two marks.

***For III I'm not so sure if its a 3/3 exactly, someone confirm?

Thank you, but i thought it has to be a physical process to MODEL it, not an actual equilibrium reaction. Am i right?

 

[porcupinetree]

Thank you, but i thought it has to be a physical process to MODEL it, not an actual equilibrium reaction. Am i right?

Yes you're right. There are actually 2 dot points involved here, one concerns a physical MODEL of equilibrium, while the other one concerns an investigation to qualitatively analyse an equilibrium reaction. sy37 seems to have mixed them up

A good model to use is 2 buckets of water with water in each, and 2 different sized beakers. Use one beaker to transfer water from one bucket to the other, then use the other beaker to transfer water from the 2nd bucket to the 1st, and continue until the amount of water in each bucket remains constant.

 

[sy37]

Yes you're right. There are actually 2 dot points involved here, one concerns a physical MODEL of equilibrium, while the other one concerns an investigation to qualitatively analyse an equilibrium reaction. sy37 seems to have mixed them up

A good model to use is 2 buckets of water with water in each, and 2 different sized beakers. Use one beaker to transfer water from one bucket to the other, then use the other beaker to transfer water from the 2nd bucket to the 1st, and continue until the amount of water in each bucket remains constant.

Holy shit lol. I didn't even know that was a dot point. I now remember i looked at it and was like this is stupid I'm not going to do it so I didn't include it in my notes

Leaving it up there to point out my stupidity

meh

 

[Ekman]

Yes you're right. There are actually 2 dot points involved here, one concerns a physical MODEL of equilibrium, while the other one concerns an investigation to qualitatively analyse an equilibrium reaction. sy37 seems to have mixed them up

A good model to use is 2 buckets of water with water in each, and 2 different sized beakers. Use one beaker to transfer water from one bucket to the other, then use the other beaker to transfer water from the 2nd bucket to the 1st, and continue until the amount of water in each bucket remains constant.

I like the candy/chocolates method of modelling it. It's where you have 20 pieces of chocolate or candy on one side of the table, and you take 50% and move it to the other side of the table. Then you take 25% of the 50% that you moved, and move it back to other side. Repeat this process till both sides have equal amounts of candy/chocolate. If there is any decimals when you are calculating how many to move, round up.

 

[thuvarahanjeg]

i)

2mL of 0.1M/L FeCL3 was mixed with 2mL of of 0.1M/L NH4SCN and diluted with distilled water to a volume of 20mL.
Fe3+(yellow) + SCN-(colourless) <--> FeSCN2+ (blood red). The initial colour was then recorded and the solution divided equally between 2 test tubes. Test tube one was placed in a hot water bath, test tube two was placed in an ice bath. By LCP, the ice bath shifted the equilibrium of this exothermic reaction to the right to turn the solution into a deeper red due to the presence of FeSCN2+ so as to counteract a decrease in temperature. Conversely, the hot water bath shifted the equilibrium to the left to favour the endothermic reaction and use more heat, making the solution a pale yellow (due to Fe3+).

ii) NH4SCN is a classified respiratory irritant, hence inhalation irritates the respiratory system.

iii) An equilibrium reaction is one in which the forward and reverse reactions have a tendency to change with disturbances. In our experiment, a hot and ice water bath were used to disturb the temperature. This allowed varying colour changes to occur in response to these disturbances as the reaction attempts to minimise these changes. A limitation of this model is that it is qualitative, hence was less accurate in determining a strict relationship

**For I, we added a bunch of other chemicals in the experiment but I kept it at temperature only here because it's only two marks.

***For III I'm not so sure if its a 3/3 exactly, someone confirm?

its a physical process mention that

 

[Drsoccerball]

I like the candy/chocolates method of modelling it. It's where you have 20 pieces of chocolate or candy on one side of the table, and you take 50% and move it to the other side of the table. Then you take 25% of the 50% that you moved, and move it back to other side. Repeat this process till both sides have equal amounts of candy/chocolate. If there is any decimals when you are calculating how many to move, round up.

lol whats the safety risk ? Diabetes?