[nicolodn]

Chemistry- Reaction kinetics, Water/equilibrium?
A 1.00 mol kg-1 sloution of H2SO4 in water boils at 101.380 degrees celsius. {Kbp (H2O)=0.51 degrees celsius kg mol-1}
calculate the concentration of particles in this solution?
______________________________________…
First order reaction of N2O4 to form 2 mol of NO2 has rate constant k=0.023 min-1. How long will it take the initial concentration of N2O4 to decrease to 10% of the original value?
a)600s, b) 100 min c)43.5s d)43.5 min e) 435 min

How to do this question?
______________________________________…
Enthalpy is a very useful thermodynamic quantity because it relates to measurements made in a system which is:
a)isolated
b)at constant pressure
c)constant temperature
d)spontaneous

[nicolodn]

Chemistry- Reaction kinetics, Water/equilibrium?
A 1.00 mol kg-1 sloution of H2SO4 in water boils at 101.380 degrees celsius. {Kbp (H2O)=0.51 degrees celsius kg mol-1}
calculate the concentration of particles in this solution?

What I did was;
changeIn T= K x m
observed; 101.38-100= 1.38 C
calculated= 0.51 x 1 x i=0.51 x i
Then 1.38/0.51= i = 2.7

I don't understand how to calculate the concentration.
Also, if my above working out is correct, does that mean that H2SO4 mainly exists as 2H+, SO4 2- ? I am confused as I thought that H2SO4 is a strong acid and so it should exist as H+, HSO4 -
______________________________________…
First order reaction of N2O4 to form 2 mol of NO2 has rate constant k=0.023 min-1. How long will it take the initial concentration of N2O4 to decrease to 10% of the original value?
a)600s, b) 100 min c)43.5s d)43.5 min e) 435 min

I am confused as to how to do this question;

I'm unsure of how to do this question as I can only think of rate=k x [NO2]

How to do this question?
______________________________________…
Enthalpy is a very useful thermodynamic quantity because it relates to measurements made in a system which is:
a)isolated
b)at constant pressure
c)constant temperature
d)spontaneous

[singed]

• First question:  yes H2SO4 is a strong acid but it will also deprotonate the second hydrgen to make 2H+ and SO4-2.  Your work looks right.  Are you sure it wasn't Na2SO4 or something else?  What you want to do is look at what i means.  i means the number of dissolved species.  Therefore you have 2.7 moles concentrate/kg water instead of the 1 mole/kg water.  Just convert the kg water into volume at that temperature.
• Second question:  the reaction rate is really rate = k * [N2O4].  However you really need to solved the differential equation d[N2O4]/dt = k*[N2O4] with initial conditions of t=0 and [N2O4]o to t=t and [N2O4]o*.1 and solving for t
• Third question:  The answer is b at constant pressure.  If you solve out the differential for enthalpy you get: dH = TdS - PdV + PdV +VdP and at constant pressure you get dH = TdS