Hello,been long since i last updated.Shall give some brief happenings for Chemistry:
#1:Promotional Examinations (1) H2 CHEMISTRY is really badly done in my perspective,excluding the "Overall Results".
#2:Chemistry topics are getting tougher,can sense it.
#3:Shall update about the term ,"Standardization" in this post,since Ms.Gee asked us to do some research for those who are not too clear about the definition.

-Standardization of a solution refers to an experiment in which the concentration of a solution is determined.
-A process in which the value of a potential standard is fixed by a measurement made with respect to a standard whose value is known.

Can't seemed to find any useful definitions!!!!!!!!!!!!

Shall talk about Ideal Gas.
Ideal Gas equation: pV=nRT
p-pressure in Pa
V-volume in m^3
n-amount in mol
R-universal gas constant (8.314)
T-temperature in K

According to the Kinetic Particle theory of gasses, an ideal gas will have:

-Volume of gas particles negligible as compared to volume of the container
-Negligible intermolecular forces between gas particles
-Gas particles are moving in constant random motion
-Gas particles collides in an perfect elastic motion

Shall talk about Energetics:
So far,we had only learnt the various definitions of different types of enthalpy change/energy.For example,Standard enthalpy change of solution,Standard enthalpy change of hydration,Standard enthalpy change of neutralisation,Standard enthalpy change of atomisation,Standard enthalpy change of reaction,Standard enthalpy change of formation,Bond dissociation energy,Lattice energy,Electrons Affinity,etc.Just remember that the standard conditions is 1atm pressure,298K in temperature.

Finally to summarise(with questions!)
Why is enthalpy change for exothermic reactions negative?
Because energy has been released to the surroundings. The products therefore have a lower enthalpy than the reactants and the final enthalpy is less than the initial enthalpy

Why is standard enthalpy changes of combustion always negative?
Because heat is always evolved, the reaction is exothermic and therefore heat is lost to the surroundings. The energy required to break bonds is always less than the energy released when bonds are formed

Alright,see ya guys! :-)
P.s:I am just plain happy and blessed recently,excluding those physical and mental pain.