Anyone who loves chemistry - exam Qtns (1 Viewer)

[scy91]

I say 'greetings' to those who love chemistry

because I'm finding it so difficult and confusing~

Thanks alot for ur help!


Multiple choice:
Q) Identify the main reason for a change in reaction rate when temperature is increased.
(A) increasing the frequency of molecular collisions
(B) decreasing the activation energy
(C) Increasing molecular kinetic energy
(D) Increasing the activation energy

Written response:
Q) The first ionisation energy of lithium is 519 KJ per mol and that of oxygen is 1310 KJ per mol.
(A) construct an equation to represent the first ionisation of oxygen
(B) identify ONE reason for the difference in above values
(C) relate the ionisation energies to the observed conductivity of lithium and hydrogen in the liquid state
(D) relate the ionisation energies to the type of ions formed by each of the above elements

Q)In the presence of a catalyst such as manganese dioxide, hydrogen peroxide solution decomposes according to the equation:
2H2O2 --> 2H2O2 + O2 (g)
A mixture of mehtane gas and air does not react unless an ignition source such as a flame or a spark is provided

Compare the effect of an ignitino source on the reaction between methane and air to the effect of a catalyst on the decomposition of hydrogen peroxide

Q)The use of nitrogen triiodide is banned in NSW schools because of safety issues. NI3 is unstable, decomposing explosively to form nitrogen gas (N2) and iodine vapour, even when subjected to slight vibrations
With an aid of Lewis electron dot diagrams, explain the exothermic nature of this decomposition of NI3 in terms of energy invovled in the breaking and formation of chemical bonds.

 

[ro.25]

oh gosh chemistry :| i do it...yet even after 8 months it still confuses me

 

[shaon0]

I say 'greetings' to those who love chemistry

because I'm finding it so difficult and confusing~

Thanks alot for ur help!


Multiple choice:
Q) Identify the main reason for a change in reaction rate when temperature is increased.
(A) increasing the frequency of molecular collisions
(B) decreasing the activation energy
(C) Increasing molecular kinetic energy
(D) Increasing the activation energy

Written response:
Q) The first ionisation energy of lithium is 519 KJ per mol and that of oxygen is 1310 KJ per mol.
(A) construct an equation to represent the first ionisation of oxygen
(B) identify ONE reason for the difference in above values
(C) relate the ionisation energies to the observed conductivity of lithium and hydrogen in the liquid state
(D) relate the ionisation energies to the type of ions formed by each of the above elements

Q)In the presence of a catalyst such as manganese dioxide, hydrogen peroxide solution decomposes according to the equation:
2H2O2 --> 2H2O2 + O2 (g)
A mixture of mehtane gas and air does not react unless an ignition source such as a flame or a spark is provided

Compare the effect of an ignitino source on the reaction between methane and air to the effect of a catalyst on the decomposition of hydrogen peroxide

Q)The use of nitrogen triiodide is banned in NSW schools because of safety issues. NI3 is unstable, decomposing explosively to form nitrogen gas (N2) and iodine vapour, even when subjected to slight vibrations
With an aid of Lewis electron dot diagrams, explain the exothermic nature of this decomposition of NI3 in terms of energy invovled in the breaking and formation of chemical bonds.

1. A
Can't be bothered to do the rest

 

[bubblesss]

I say 'greetings' to those who love chemistry

because I'm finding it so difficult and confusing~

Thanks alot for ur help!


Multiple choice:
Q) Identify the main reason for a change in reaction rate when temperature is increased.
(A) increasing the frequency of molecular collisions
(B) decreasing the activation energy
(C) Increasing molecular kinetic energy
(D) Increasing the activation energy

Written response:
Q) The first ionisation energy of lithium is 519 KJ per mol and that of oxygen is 1310 KJ per mol.
(A) construct an equation to represent the first ionisation of oxygen
(B) identify ONE reason for the difference in above values
(C) relate the ionisation energies to the observed conductivity of lithium and hydrogen in the liquid state
(D) relate the ionisation energies to the type of ions formed by each of the above elements

Q)In the presence of a catalyst such as manganese dioxide, hydrogen peroxide solution decomposes according to the equation:
2H2O2 --> 2H2O2 + O2 (g)
A mixture of mehtane gas and air does not react unless an ignition source such as a flame or a spark is provided

Compare the effect of an ignitino source on the reaction between methane and air to the effect of a catalyst on the decomposition of hydrogen peroxide

Q)The use of nitrogen triiodide is banned in NSW schools because of safety issues. NI3 is unstable, decomposing explosively to form nitrogen gas (N2) and iodine vapour, even when subjected to slight vibrations
With an aid of Lewis electron dot diagrams, explain the exothermic nature of this decomposition of NI3 in terms of energy invovled in the breaking and formation of chemical bonds.

1) A
2)a)O ->O^- = 1310 Kj
b) changes because ionization energy increases across a periodic table and because it becomes harder to remove an outer shell electron as we move from left to right in a periodic table.
c) not sure
d)since lithium has only one outer shell electron it readily loses its electron to gain the stable gas configuration of helium hence it has a low ionization energy and forms a positive ion. since oxygen has an extremely high ionization energy it is difficult to extract electrons from it. it is way easier for it to attract 2 electrons. thus oxygen always forms negative ions.
hope i helped:wave: .

 

[lolokay]

"(B) identify ONE reason for the difference in above values
(C) relate the ionisation energies to the observed conductivity of lithium and hydrogen in the liquid state
(D) relate the ionisation energies to the type of ions formed by each of the above elements"

b) oxygen has a smaller radius, due to increased nuclear attraction from greater number of protons. This means a greater amount of energy would be needed to 'pull off' an electron

c) conductivity is the flow of electrons, so if less energy is required to pull off an electron, the substance will be more conductive

d) lithium becomes a cation (positive) since it is easier to remove all outer shells to give it a stable state. Oxygen forms anions (negative) since it is easier for it to gain electrons to produce a stable state


"Q)In the presence of a catalyst such as manganese dioxide, hydrogen peroxide solution decomposes according to the equation:
2H2O2 --> 2H2O + O2 (g)
A mixture of mehtane gas and air does not react unless an ignition source such as a flame or a spark is provided

Compare the effect of an ignitino source on the reaction between methane and air to the effect of a catalyst on the decomposition of hydrogen peroxide"

the igniting source only initiates the reaction - from then on it is combustion. The catalyst merely speeds up the reaction while it is present


"With an aid of Lewis electron dot diagrams, explain the exothermic nature of this decomposition of NI3 in terms of energy involved in the breaking and formation of chemical bonds."

I would imagine it is due to NI3 having only single bonds, but N2 having triple bonds - and is thus in a more stable state since it is harder to separate the individual atoms


can't guarantee that answers are 100% correct