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How can you tell whether a reaction is endothermic or exothermic?
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How do you know it is a exothermic reaction?
If you are in a lab and want to tell whether a reaction was exothermic, carefully check the temperature of the reaction vessel. If the reaction was exothermic, the vessel will be warmer than it was before the reaction occurred. If you are looking at a reaction on paper, you will need a table of thermodynamic data. It should contain the molar enthalpies of formation, represented by H, of each of the reactants and products (note: if a reactant or product is an element in its most stable state, like H2(g) or Zn(s), the enthalpy of formation is defined as zero, so they may be left out of the table). Multiply the number of moles of each product and reactant by its molar enthalpy. Add up all the results for the products and subract all the results for the reactants. If your net result is negative, the reaction was exothermic. If it is positive, the reaction was endothermic. Example: CH4(g)+2O2(g)-->CO2(g)+2H2O(g) Delta H (kJ/mol) CH4(g) -74.8 O2(g) 0 CO2(g) -393.5 H2O(g) -241.82 Products: 2(-241.82)+(-393.5)= -877.14 kJ Reactants: -74.8+2(0)= -74.8 kJ Total: -877.14-(-74.8)= -802.34 kJ The reaction was exothermic.
How do you tell endothermic reaction from an exothermic reaction by looking at the chemical equation?
You have to add up the bond energies of all the bonds on the products side and the reactants side. When bonds are formed energy is released. Conversely energy has to be put into a system to break bonds (like smashing a block of ice with a baseball bat) If there is more bond energy on the products side bonds were created (energy was released) which means the reaction is exothermic. If there is more bond energy on the reactants side, bonds were broken (energy put in) and so the reaction is endothermic.
Is sweating a chemical reaction?
Oddly enough, evaporation is endothermic. To tell the difference, simply ask yourself, must heat be added or taken away for a phase change to occur. If heat must be added it is endothermic, if heat must be taken away it is exothermic. In the case of evaporation in most cases you must raise the temperature for a substance to evaporate, thus it is endothermic.
Is the combustion of methane an exothermic or endotermic?
Endothermic means that the net energy produced when chemical bonds reform is less that the energy required to break the original bonds. (It gets cold because it need more energy from the surrounding molecules)Exothermic means that the net energy produced is more than the required energy to break the original bonds. (it gets hot because it releases energy)Using logic and personal experiences, when you ignite something, such as methane, it burns. just the fact that it burns shows that it is releasing energy in the form of light/heat. this makes the combustion of methane Exothermic.
How can you tell dissolving ammonium nitrate is exothermic?
Dissolution is generally exothermic.
How can you tell the difference between an endothermic and exothermic reaction?
You can generally tell by changes in temperature, whether you have an exothermic reaction which produces heat, or an endothermic reaction which consumes heat.
What does the potential energy diagram of a chemical reaction tell you?
Whether the reaction is endothermic or exothermic
Was the reaction of hydrogen and oxygen endothermic or exothermic How could you tell?
To produce water? Exothermic and very much so.Take a mixture, spark it and it will burn or explode. Heat energy is given off far in excess of whatever energy was needed to start the reaction.
What is the word used to describe a chemical reaction in which energy is released?
Any chemical reaction that releases energy is called an exothermic action. The equations for an exothermic reaction between substance A and substance B would be: A + B --> AB + Heat The heat represents the energy and we can tell it is being released because it is on the product side of the equation. The reverse reaction would be endothermic, meaning it requires energy, heat would be on the reactant side and the equation would be: AB + Heat --> A + B To sum things up, an exothermic reaction releases energy and heat will be on the product side of the equation. An endothermic reaction requires energy and heat will be on the reactant side of the equation.
What does h tell about a reaction?
The reaction is exothermic.
What does a negative deltaH tell about a reaction?
the reaction is exothermic
What does a negative H tell about a reaction?
The reaction is exothermic.
What does a positive H tell about a reaction?
The reaction is endothermic.
What does a positive delta H tell about reaction?
This is an endothermic chemical reaction.
How do you know it is a exothermic reaction?
If you are in a lab and want to tell whether a reaction was exothermic, carefully check the temperature of the reaction vessel. If the reaction was exothermic, the vessel will be warmer than it was before the reaction occurred. If you are looking at a reaction on paper, you will need a table of thermodynamic data. It should contain the molar enthalpies of formation, represented by H, of each of the reactants and products (note: if a reactant or product is an element in its most stable state, like H2(g) or Zn(s), the enthalpy of formation is defined as zero, so they may be left out of the table). Multiply the number of moles of each product and reactant by its molar enthalpy. Add up all the results for the products and subract all the results for the reactants. If your net result is negative, the reaction was exothermic. If it is positive, the reaction was endothermic. Example: CH4(g)+2O2(g)-->CO2(g)+2H2O(g) Delta H (kJ/mol) CH4(g) -74.8 O2(g) 0 CO2(g) -393.5 H2O(g) -241.82 Products: 2(-241.82)+(-393.5)= -877.14 kJ Reactants: -74.8+2(0)= -74.8 kJ Total: -877.14-(-74.8)= -802.34 kJ The reaction was exothermic.
How do you tell endothermic reaction from an exothermic reaction by looking at the chemical equation?
You have to add up the bond energies of all the bonds on the products side and the reactants side. When bonds are formed energy is released. Conversely energy has to be put into a system to break bonds (like smashing a block of ice with a baseball bat) If there is more bond energy on the products side bonds were created (energy was released) which means the reaction is exothermic. If there is more bond energy on the reactants side, bonds were broken (energy put in) and so the reaction is endothermic.
Is sweating a chemical reaction?
Oddly enough, evaporation is endothermic. To tell the difference, simply ask yourself, must heat be added or taken away for a phase change to occur. If heat must be added it is endothermic, if heat must be taken away it is exothermic. In the case of evaporation in most cases you must raise the temperature for a substance to evaporate, thus it is endothermic.
