Pressure-volume work is needed to inflate a balloon.
2 is against which it expands.
The system's contents are 1.00 atm.
1 L # atm is 101.3 J joules.
The units are correct for work.
The sign of the work is negative, as it should be for an expansion, because work is done on the surroundings by the balloon.
The cylinder expands against an external pressure of 1.58 atm.
When fuel is burned in a cylinder, the volume expands from 0.255 L to 1.45 L against an external pressure of 1.02 atm.
The heat is emitted as 875 J.
The heat flow can cause a temperature change.
To use a bomb calorimeter, we put the sample to be burned into a cup with an ignition wire.
The container has something on it.
We ignite the sample with a wire coil and then use the thermometer to check the temperature.
The quantity is the change in the internal energy of the reaction.
The temperature goes up from 24.92 to 28.33 degrees Centigrade when 1.010 g of sucrose undergoes combustion in a bomb calorimeter.
The bomb calorimeter has a heat capacity of 4.90 kJ.
There are three parts to the conceptual plan.
The units of the answer are correct.
The temperature goes up from 25.87 degC to 38.13 degC when 1.550 g of liquid hexane undergoes combustion in a bomb calorimeter.
The bomb calorimeter has a heat capacity of 5.73 kJ.
The temperature goes up from 23.12 degC to 37.57 degC when toluene is burned in a bomb calorimeter.
When a chemical reaction occurs open to the atmosphere under constant pressure, the energy can evolve into both heat and work.
We are only interested in the heat exchanged, not the work done.
When we burn natural gas on a stove to cook food, we just want to know how much heat is given off to cook the food, because we don't really care how much work the combustion reaction does on the atmosphere.
The two terms on the right can be understood with the help of relationships that are familiar to us.
Natural gas is released into the air surrounding it.
A good example of an endothermic reaction is the reaction that occurs in a chemical cold pack.
The substances mix, react, and absorb heat when they are in a chemical cold pack.
Section 7.1 talks about an exothermic reaction that occurs in the chemical hand warmer.
When the reaction takes place, heat is given off into the surroundings, making them warmer.
The burning of natural gas is an exothermic reaction.
As the gas burns, it raises the temperature of its surroundings.
The endothermic reaction feels cold.
It feels warm to the touch.
The perspiration needs heat from the skin in order to continue to evaporate.
The water in the freezer needs to be kept warm in order for it to continue to freeze.
The thermal energy of a system is the total energy of the atoms and Molecules.
In exothermic reactions, the temperature of the system and surroundings increases.
There must be more than one source of energy.
The source of potential energy is a chemical reaction.
Chemical potential energy is usually created by the forces between the protons and electrons in the system.
In an exothermic reaction, some bonds break and new ones form, and the nucleus and electrons reorganize into an arrangement with lower potential energy.
As the atoms rearrange, their potential energy is converted into thermal energy.
Weak bonds break and stronger bonds form.
It only takes a small amount of energy to break the weak bonds, and a larger amount when the stronger bonds form, resulting in net energy production.
The nuclei and electrons reorganize into an arrangement with higher potential energy.