Chapter 12, Problem 12.1Q

Review Figure 12-13. Use this figure to write a few sentences (or at least draw on analogy) explaining why, when you strike the head of a safety match slowly on its pumice with little pressure, it may heat up a little, but does not ignite, yet when you put pressure on it and strike it rapidly, it does ignite. Thanks to Oscar Piedrahita, Medellín, Colombia.

Interpretation Introduction

Interpretation:

The reason corresponding to the fact that that if the head of a safety match is slowly strike over its pumice with some pressure, it just little bit heat up but does not get ignited is to be stated.

Concept introduction:

The force that is applied over the surface of a substance perpendicularly per unit to its area on which the force is applied is known as pressure. The SI unit of pressure is Pascal. A particular amount of applied pressure is required to activate a reaction by elevating the energy from lower state to higher state.

Answer to Problem 12.1Q

If the head of a safety match is slowly strike over its pumice with some pressure, it just little bit heat up but does not get ignited because high amount of pressure is required to increase the temperature corresponding to the head of match stick, $T_{\text{s}}$.

Explanation of Solution

The given ignition extinction temperature curve is given as follows.

Figure 1

Where,

• $T_{\text{s}}$ is the temperature corresponding to the head of match stick.
• $T_{\text{0}}$ is the temperature of the surrounding.

If the match stick strikes on the pumice with little pressure then it just little bit heat up and does not get ignited. On the other hand, if pressure higher pressure is applied while striking the match stick on its pumice then it gets ignited. The reason corresponding to the fact is that is match stick strikes with little pressure then it shifts with points 1 to 5 shown in the curve. Therefore, due to little applied pressure, not enough frictional force is produced to take the required jump from the lower steady state to the higher steady state.

Thus, for the ignition of the match stick, the enough amount of pressure is required to take the required jump from the lower steady state to the higher steady state. This jump increases the temperature corresponding to the head of match stick, $T_{\text{s}}$ and generates the sufficient frictional force to ignite the match stick.

Conclusion

If the head of a safety match is slowly strike over its pumice with some pressure, it just little bit heat up but does not get ignited because high amount of pressure is required to increase the temperature corresponding to the head of match stick, $T_{\text{s}}$.