Answer:
Explanation:
A <em>combustion reaction</em> is the reaction with oxygen along with the release of energy in form of heat or light.
Organic compounds (like CH₄) undergo combustion forming water and CO₂.
The combustion reaction of CH₄ is:
Hence, the first equation from the choices is not showing the combustion reaction of CH₄.
Not only organic compounds can undergo combustion. Metals and no metals can undergo combustion, i.e. metals and no metals can react with oxygen releasing light or heat.
The reaction of copper and oxygen (second choice) is a combustion reaction:
The formation of water (2H₂ + O₂ → 2H₂O) is other example of a combustion reaction where no organic compounds are involved.
On the other hand, the other two equations from the choice list are not reactions with oxygen, so they do not show combustion reactions.
Answer:
It sounds like they are studying French phonemes
Explanations:
I just learned this.
The graph is needed to answer this question.
Solubility may increase or decrease with temperature depending on the properties of the solute and the solvent.
It is quite common that the solubility of the ionic compounds, like KBr, in water increases with temperature.
Use your solubility curve for the KBr and you wiil see a line that starts at a solubility a little greater than 50 grams of the salt in 100 grams of water for temperaute 0°C and increase linearly until almost 100 grams of the salt in 100 grams of water at 100°C.
So, in this case you can affirm that the solubility of KBr increases with the temperature.
Answer: the second option: the solubility increases.
Answer:
In a favorable reaction, the free energy of the products is less than the free energy of the reactants.
Explanation:
The free energy of a system is the amount of a system's internal energy that is available to perform work. The different forms of free energy include Gibbs free energy and Helmholtz free energy.
In a system at constant temperature and pressure, the energy that can be converted into work or the amount of usable energy in that system is known as Gibbs free energy. In a system at constant temperature and volume, the energy that can be converted into work is known as Helmholtz free energy.
The change in free energy of a system is the maximum usable energy that is released or absorbed by a system when it goes from the initial state (i.e., all reactants) to the final state (i.e., all products).
In a chemical reaction, some bonds in the reactants are broken by absorbing energy and new bonds are formed in the products by releasing energy. As the reaction proceeds, the free energy of reactants is much greater than the products. As the products are formed, the concentration of reactants decreases and the difference in their free energy also decreases. This chemical reaction will occur until chemical equilibrium is achieved i.e., the free energy of the products and reactants is equal and the difference in their free energy is zero.
