Order of reaction question?

for the reaction 2NOBr(g)----->2NO(g) +Br2(g), the rate of equation is -d[NOBr]/dt =k[NOBr]^2. the overall rate reaction =


how do you go about doing this question? my answer appears to be wrong....I have a choice of 1,-1,2 and 0.5

joeyeehu...

Best Answer - Chosen by Voters

When you are given a rate equation, you can easily tell the overall order of reaction.

lets the rate equation be
rate = k [X] [Y]^2 [Z]^3

We can conclude that:
1) The order of reaction with respect to (wrt) X is 1( because the equation shows that the concentration of X is raised to power 1)
2) The order of reaction wrt Y is 2.
3) The order of reaction wrt Z is 3

4) The overall order of reaction is 1 + 2 + 3 = 6

So, the answer to your question is 2.

Help with this tough AP Chemistry Problem?

N2(g) + 2O2(g) <-->N2O4(g)

If the value of the equilibrium constant with regard to pressure (Kp) is found to be 1.5 at 15°C, what is the value of the eqilibrium constant with regard to concentration?
(R = 0.0821 L•atm/(mol•K))



a. 8.4 x 102
b. 2.3
c. 9.4 x 107
d. 2.7 x 10–3

joeyeehu...

Best Answer - Chosen by Voters

Assume that the unit of Kp is atm-2.

Kp = Kc ( RT) ^ -2

Substitute the values into the equation, (a) is the answer.

T= 15 + 273 K
-2 is the number of moles of the products minus the number of moles of ractants. ( 1 - 3 = -2 )

I got a question about aluminum- tough AP chemistry problem...?

The Hall-Héraoult process for the electrolysis of aluminum oxide uses the mineral substance, cryolite (Na3AlF6), which of the following is not a reason for using cryolite?
a. Aluminum oxide dissolves in molten cryolite.
b. Molten cryolite is able to conduct an electrical current.
c. The aluminum in cryolite serves a a nucleation site for the reduction reaction.
d. Cryolite melts at a much lower temperature than aluminum oxide, thus lowering the energy costs of the reduction process.

joeyeehu...

Best Answer - Chosen by Voters

c

Energy Levels and Orbitals:?

What is the relationship between energy levels and orbitals?

joeyeehu...

Best Answer - Chosen by Voters

Energy levels can associated with the electron shells or the principal quantum numbers. The higher the number the higher the energy levels.

Each principal quantum number (n) can have a certain orbitals.

For n = 1, there is only one type of orbital namely s orbital
For n = 2, there are s orbitals and p orbitals where the p orbitals are of higher energy than s orbitals

For n = 3 -> s , p and d orbitals

and so on.

Although the rule says that the higher the principal quantum number the higher the energy level, there are a few exceptions. Example, 4s orbital is lower in energy than 3d orbital.....

HETEROGENEOUS CATALYSIS

HETEROGENEOUS CATALYSIS

Explain what is meant by the term " heterogeneous catalysis ".
Give an example and explain how the catalyst works.

In heterogeneous catalysis, the physical state of the catalyst is different from that of the reactants.

Example of heterogeneous catalysis is the reaction between gaseous iodine and hydrogen to form hydrogen iodide catalysed by solid platinum. Pt(s)

H2(g) + I2(g) ------------> 2HI(g)

Solid platinum provides a suitable surface for the adsorption of the hydrogen and iodine molecules. This is possible because platinum has many empty or half-filled d-orbitals that can be used to form temporary bonds with the reacting molecules.

The adsorption process not only increases the concentration of the reactants on the platinum surface, it also weakens the covalent bonds in the molecules which leads to a decrease in the activation energy. Furthermore, the reacting molecules are now in the correct orientation for new bonds to be formed.



----H----H----I---------I----H----H----I---------I----H----H----
temporary bonds
________________________________________________
Platinum surface

* the bonds between H-H and I-I are being broken.
* the bonds between H-I are being formed


After that, the HI molecules are released from platinum surface so that other reactant molecules can be adsorbed.

HOMOGENEOUS CATALYSIS

HOMOGENEOUS CATALYSIS

Explain what is meant by the term "homogeneous catalysis".
Give an example and explain how the catalyst works.
Homogeneous catalysis is a reaction where the physical states of the catalyst is the same as that of the reactants.

Example of homogeneous catalysis is the reaction between aqueous iodide ion and aqueous peroxodisulphate ion catalysed by aqueous iron(III) ion. Fe3+

S2O82-(aq) + 2I-(aq) ------------> I2(aq) + 2SO42-(aq)

In the presence of aqueous iron(III) ion, the reaction occurs in two steps.

Step 1 : 2Fe3+(aq) + 2I-(aq) ----------> 2Fe2+(aq) + I2(aq)
Step 2 : 2Fe2+(aq) + S2O82-(aq) ----------> 2Fe3+(aq) + 2SO42-(aq)

The catalysed reaction has lower activation energy because it involves the collision of oppositely charged particles while the uncatalysed reaction involves the collision of like charged particles.

Homogeneous catalyst works by forming an intermediate (Fe2+) and then being regenerated in the following step. Fe3+ ion manages to do so because it can vary its oxidation states between +3 and +2. By doing so, it helps to transfer the electron from I- to S2O82-.

Which of the following contains an sp2-hybridized carbon?

CH4
CH3:-
CH3CH3
CH3+
HC(triple bond)CH

joeyeehu...

Best Answer - Chosen by Voters

It is CH3+

There are 3 pairs of electrons around the carbon atom.
This suits the sp2 hybridised orbitals of carbon and it will take the shape of trigonal planar.

CH3- is not sp2 hybridised. It is sp3 hybridised.
There are 4 pairs of electrons around the carbon atom.
Although it is sp3 hybridised, the shape is trigonal pyramidal because there is a lone pair of electrons.