Spontaneous Reactions: Forward, Backwards, Both or None?

In summary, the process of water and syrup mixing to give a flavored drink is considered to be backwards because it requires stirring. The reaction of a piece of paper with oxygen to produce CO2 and H2O at room temperature is considered to be none, as it is a very slow process. The cooling of bathtub water after staying in it for too long is considered to be a forward process. Finally, the freezing of water at 10C and 1 atm is considered to be backwards because water does not typically freeze at this temperature.
  • #1
higherme
129
0

Homework Statement



Find whether the following is spontaneous. Forward= (process as written), backwards, both or none

Homework Equations


1. water & syrup mixed to give a flavoured drink
2. Piece of paer at room temp react with O2 to give CO2 and H2O
3. Bathtub water gets cold after you stay in too long
4. Water freezes at 10C & 1 atm

The Attempt at a Solution


1. backwards b/c you have to stir it for water and syrup to mix
2. none? I'm not sure about this one. I don't think paper can react to give water.
3. Forward
4. backwards - water doesn't freeze at 10C

Can someone double check this for me, thanks in advance!
 
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  • #2
higherme said:
1. backwards b/c you have to stir it for water and syrup to mix

Not necesarilly - mixing goes on its own, albeit very slowly.

2. none? I'm not sure about this one. I don't think paper can react to give water.

Every compound containing carbon and hydrogen gives CO2 and H2O when it burns. Check what is paper made of. Again, oxidation without burning is a very slow process, but it goes on its own.

--
methods
 
  • #3
higherme said:

Homework Statement



Find whether the following is spontaneous. Forward= (process as written), backwards, both or none

Homework Equations


1. water & syrup mixed to give a flavoured drink
2. Piece of paer at room temp react with O2 to give CO2 and H2O
3. Bathtub water gets cold after you stay in too long
4. Water freezes at 10C & 1 atm

The Attempt at a Solution


1. backwards b/c you have to stir it for water and syrup to mix
This is so easy an English major could answer it. Your question stated, "1. water & syrup mixed...". emphasis mine.


The rest look OK.
 

1. What are spontaneous reactions?

Spontaneous reactions are chemical reactions that occur without the need for external energy input. They are driven by thermodynamic factors, such as changes in entropy and Gibbs free energy, and tend to occur in the direction that increases the disorder or randomness of the system.

2. How do spontaneous reactions occur in both forward and backward directions?

Spontaneous reactions can occur in both forward and backward directions because they are reversible reactions. This means that the products of the reaction can also act as reactants and vice versa. The direction of the reaction is determined by the relative concentrations of the reactants and products, as well as the thermodynamic factors mentioned previously.

3. What determines whether a reaction will occur spontaneously in the forward or backward direction?

The direction of a spontaneous reaction is determined by the Gibb's free energy change (ΔG) of the reaction. If ΔG is negative, the reaction will occur spontaneously in the forward direction. If ΔG is positive, the reaction will occur spontaneously in the backward direction. If ΔG is zero, the reaction is at equilibrium and will not spontaneously occur in either direction.

4. Can a spontaneous reaction be reversed by adding external energy?

Yes, a spontaneous reaction can be reversed by adding external energy. This energy can come in the form of heat, light, or electricity, and can be used to overcome the thermodynamic factors driving the reaction in one direction. However, once the external energy is removed, the reaction will resume its spontaneous direction.

5. How are spontaneous reactions important in biological systems?

Spontaneous reactions play a crucial role in biological systems, where they are responsible for many essential processes such as metabolism, growth and repair. In living organisms, enzymes and other molecules help to lower the activation energy required for these reactions to occur spontaneously, allowing for efficient and controlled chemical reactions to take place.

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