CHEMICAL

Law of Conservation of Energy

Law of conservation of energy states that energy can not be created or destroyed, but energy can be transformed from one form of energy into another form of energy. Example: solar light energy is converted into chemical energy in the form of carbohydrates. Carbohydrates are converted by humans or animals into heat energy back after digested, so the human body and animals keep warm.

1. System and Environment
The system is part of the universe to be studied, while everything outside the system is called the environment. Example: test tubes containing 5 mL of 0.1 M NaOH solution NaOH solution as the system while the test tube and the air around the tube is as environmentally.

2. Heat Reaction
Heat is the reaction of the system to move the heat to the environment or from the environment to the system so that the system temperature after a reaction similar to the system before the reaction temperature.

Kinds / Types of Heat Reaction

a. Exothermic reaction
Exothermic reaction is a reaction which results in heat transfer from the system to the environment. Marked with rising temperature or solvent mixture becomes hot. Example: The reaction between HCl solution with NaOH solution. The temperature of the solution as the system will go up which will eventually return to normal.
Another example is the reaction between the aluminum metal with bromine to form aluminum bromide / AlBr3. Bromine vapor evaporates produce brown. Exothermic reaction between aluminum and bromine vapor causes brown maikn much.
 2AL (s) + 3 Br2 (l) -> 2AlBr3 (s)

b. Endothermic reaction
Exothermic reaction is a reaction which results in heat transfer from the environment to the system. Example: The reaction between ammonium carbonate with acetic acid.
Ammonium carbonate [(NH4) 2CO3] is acetic acid CH3COOH
The temperature of the mixture of the two solutions will be down / becoming colder than the original which will eventually return to normal.
Another example is barium nitrate with ammonium hydroxide oktahidrat.
Ba (OH) 2.8H2O (s) + 2NH4NO3 (s) -> Ba2 + (aq) + 2NO3-(aq) + 2NH3 (aq) + 10H2O (l)
Heat Capacity Calorimeter
The amount of heat (q) are released or received by a system similar to the system of mass (m) multiplied by the heat capacity (c) and an increase or decrease in temperature? T.
Q = m. c. ? T
Calorimeter Heat capacity is the capacity to absorb or release energy in each degree of temperature change. Often called water equivalent.

3. Enthalpy changes
To boil one liter of water with water 5 liters of fuel oil used different numbers. That is because the oil contains certain heat content. The amount of heat that is used to raise the temperature of 1 gram of water 10C for diesbut 1 calorie / 1 calorie = 4.184 joule. If the reaction takes place at a constant pressure and the reaction was no other business except the change in volume, heat of reaction is called the enthalpy change of the emblem? H.
According to the agreement:
exothermic reactions are negative dH / -
endothermic reactions have positive dH / +
dH read delta H, triangle symbol