5. Gather data: A useful way to compare reaction rates is to record the time required for half of the reactants to react, called the half-life of the reaction. With the Temperature set to 175 °C, click Play. Record the half-life time in the first space of the table below.

Question

5. Gather data:  A useful way to compare reaction rates is to record the time required for half of the reactants to react, called the half-life of the reaction. With the Temperature set to 175 °C, click Play.  Record the half-life time in the first space of the table below.

|Trial |   175 °C   |  145 °C  | 100 °C |  65 °C  |
|        |                   |              |             |              |
|   1   |                   |              |             |               |
|       |                    |              |             |               |
|  2   |                    |              |             |               |

\Mean half-life Show all work \              |                  |                 |

Repeat the experiment at different temperatures to complete the table. (Note: To get exact times, you can refer to the TABLE tab.)

6. Calculate: Calculate the mean half-life for each temperature. Fill in these values above.

(Hint: To get an exact mean, first convert each time to seconds by multiplying the minutes value by 60 and adding this to the seconds. To find the mean in seconds, add up the two times and divide by two. Convert the answer back to minutes and seconds.)

1. Draw conclusions: For two molecules to react, they must collide at just the right angle and with enough energy to break the original bonds and form new ones. Based on these facts, why does the reaction tend to go more quickly at higher temperatures?

2. Apply: Paper must be heated to 234 °C to begin reacting with oxygen. This can be done by putting the paper over a flame. Why do you think the paper must be heated to start burning?

GPT-4o mini · Answer

### Gather Data |Trial | 175 °C | 145 °C | 100 °C | 65 °C | |--------|----------------|--------------|-------------|--------------| | 1 | [Time1] | [Time1] | [Time1] | [Time1] | | | [Time2] | [Time2] | [Time2] | [Time2] | | 2 | [Time1] | [Time1] | [Time1] | [Time1] | | | [Time2] | [Time2] | [Time2] | [Time2] | ### Calculate Mean Half-Life 1. Convert times from minutes:seconds to total seconds. 2. Calculate the mean half-life for each temperature: - **Mean (in seconds) = (Time Trial 1 + Time Trial 2) / 2** - Convert back to minutes:seconds. **Example Conversion:** If Trial 1 is 2 minutes and 30 seconds: - Convert to seconds: $ (2 \times 60) + 30 = 150 \text{ seconds} $ If Trial 2 is 3 minutes and 15 seconds: - Convert to seconds: $ (3 \times 60) + 15 = 195 \text{ seconds} $ - Mean in seconds: $ (150 + 195)/2 = 172.5 \text{ seconds} $ - Convert back to minutes: - 172.5 seconds = 2 minutes and 52.5 seconds. ### Conclusions 1. **Why does the reaction tend to go more quickly at higher temperatures?** - As temperature increases, the kinetic energy of molecules also increases. This results in more frequent and vigorous collisions between the reacting particles. More particles have enough energy to overcome the activation energy barrier needed for a reaction to occur, thus increasing the reaction rate. Moreover, higher temperatures can facilitate the breaking of bonds and the formation of new bonds, leading to faster reactions. 2. **Why must paper be heated to 234 °C to start burning?** - Paper must be heated to a certain temperature to provide the energy necessary for the combustion reaction to initiate. At 234 °C, the heat provides enough energy to break the bonds in the cellulose fibers of the paper, which allows them to react with oxygen rapidly and start burning. The energy input is essential to overcome the activation energy barrier that must be surpassed for the chemical reaction of combustion to proceed.