This question is from grade 12 university preparation level. The answer has to do something with rates of chemical reactions but I don't know what the answer is.
. When hydrogen peroxide H2O2 is used as an antiseptic on open wounds, bubbles form as a result of the following chemical reaction.
H2O2(aq) --------------> 2H2O(l) + O2(g)
This same hydrogen peroxide decomposes very slowly via the same chemical reaction when left in a bottle, even if temperature is increased to 36.8 oC (body temperature). Explain the two observations.
Blood contains a protein and that acts as a catalyst t speed up the rate of the decomositioin. H2O2 in a bottle aty body temperature contains no catalyst.
I know increasing the temperature doesn't increase the rate of reaction of all reactions but why doesn't the rate of reaction increase in this situation?
The point is that the H2O2 lasts for a long time if kept on a shelf in its original bottle (which by the way is dark to keep photons from encouraging decomposition). The effect of temperature is minor if in the range from room temp to body temp.
However if you pour it on your bleeding wrist, your blood encourages the decomposition as a little waming never would.
Damon is right. You've missed the whole point. The point is that H2O2 in a dark bottle (capped) in a dark room at 3 o C will decompose but very very slowly over time. H2O2 at 37o C poured on a cut (with blood) decomposes much more rapidly because the blood acts as a catalyst. Look up in your text or in a dictionary and read about a catalyst and how a catalyst affect the rate of a reaction.
To explain the two observations, we need to understand the concept of reaction rates in chemical reactions.
The first observation states that when hydrogen peroxide is used as an antiseptic on open wounds, bubbles form. This occurs because the hydrogen peroxide decomposes rapidly to produce oxygen gas (O2) and water (H2O). The presence of the wound provides a large surface area for the reaction to take place, leading to the generation of bubbles.
The second observation mentions that hydrogen peroxide decomposes very slowly, even at an increased temperature of 36.8°C, when left in a bottle. This happens because the rate of a chemical reaction is influenced by several factors, including temperature, concentration, surface area, and the presence of catalysts.
In this case, the slow decomposition of hydrogen peroxide indicates a low reaction rate. While increasing the temperature does tend to increase reaction rates, it may not be sufficient to significantly speed up the decomposition of hydrogen peroxide. This is because the reaction is known to have a high activation energy, which is the amount of energy required for a reaction to occur. Even with the increased temperature, the activation energy barrier is not easily overcome, resulting in a slow reaction rate.
To summarize, the first observation of rapid decomposition of hydrogen peroxide on open wounds is due to the large surface area and the presence of catalysts (enzymes) that facilitate the reaction. The second observation of slow decomposition in a bottle, even with increased temperature, is because the high activation energy barrier hinders the reaction from proceeding at a faster rate.