What Is There to Know About Chemistry?
WHAT IS THERE TO KNOW ABOUT CHEMISTRY ?
1) Matter – anything that has mass and occupies space 2) Laws/Theories- mathematical statements of behaviour of matter 3) Properties- characteristics that describe matter; use to determine its usefeulness (a) Physical- properties which can be observed/measured without a change in the composition of the substance (b) Chemical – properties which can be observed/measured only after a change in the composition of the substance
Chemical change- change in the composition of the substance
Chemical equation- expression/language of a chemical change 4) Energy – driving force of all changes/capacity to do work
Types : Potential – stored energy Due to position- Due to motion- Vibrational motion of a plucked guitar Translational motion of a moving bullet Kinetic motion of moving molecules
Energy at Work-
Laws of Thermodynamics (c) Law of Conservation of Energy- Energy cannot be created nor destroyed, it can only be transformed from one form to another form. * Bookeeping of energy
A + B = C
Situation | Seem to Be | Actual | Type of Energy Flow | C < A + B | Energy was destroyed | Some of A and B was converted into energy and was inevitably lost as HEAT | EXOTHERMIC | C > A + B | Energy was created | A and B absorbed Heat from outside to form C | ENDOTHERMIC | (d) Second Law of Thermodynamics
Do all changes spontaneously occur(bound to happen)?
What will bound to happen in each of the following situation? 1. 2. 3.
What are the reasons behind in the spontaneous changes of the above situations ? | Attainment of low energy state | | Endothermic heat flowIncrease in entropy | | Exothermic heat flow |
Entropy- degree of disorderliness
The rationale of an spontaneous change are
1) Matter – anything that has mass and occupies space 2) Laws/Theories- mathematical statements of behaviour of matter 3) Properties- characteristics that describe matter; use to determine its usefeulness (a) Physical- properties which can be observed/measured without a change in the composition of the substance (b) Chemical – properties which can be observed/measured only after a change in the composition of the substance
Chemical change- change in the composition of the substance
Chemical equation- expression/language of a chemical change 4) Energy – driving force of all changes/capacity to do work
Types : Potential – stored energy Due to position- Due to motion- Vibrational motion of a plucked guitar Translational motion of a moving bullet Kinetic motion of moving molecules
Energy at Work-
Laws of Thermodynamics (c) Law of Conservation of Energy- Energy cannot be created nor destroyed, it can only be transformed from one form to another form. * Bookeeping of energy
A + B = C
Situation | Seem to Be | Actual | Type of Energy Flow | C < A + B | Energy was destroyed | Some of A and B was converted into energy and was inevitably lost as HEAT | EXOTHERMIC | C > A + B | Energy was created | A and B absorbed Heat from outside to form C | ENDOTHERMIC | (d) Second Law of Thermodynamics
Do all changes spontaneously occur(bound to happen)?
What will bound to happen in each of the following situation? 1. 2. 3.
What are the reasons behind in the spontaneous changes of the above situations ? | Attainment of low energy state | | Endothermic heat flowIncrease in entropy | | Exothermic heat flow |
Entropy- degree of disorderliness
The rationale of an spontaneous change are