Ingrid's Day 4 Sr.Project

May 11, 2023

Ingrid's Day 4 Sr.Project

Ingrid Wu's Day 4 Blog

May 11 2023

What type of relationship is the Carbon Dioxide decrease in the machine?

I am investigating the relationship between the time and the carbon dioxide level in the box. I am curious about the relationship because I used to calculate the rate of change by simply assuming that it will be the linear equation. To confirm that, I ran three tests today and collected data every five minutes to get many points for getting the equation.

The following graphs are created by using the data I collected today.

This is absolutely surprising to me in various aspects.

Firstly, the relationship of the decrease and the time is exponential decay instead of linear decrease, as I thought before. The first 5 to 10 minutes is the period where the CO2 in the box decreased the most. After that, the points came together because the minimum CO2 the sensor can detect is 201ppm, meaning that we cannot see any level below this amount.

Secondly, I assumed that more Ca(OH)2 will give me a faster decrease rate, while from what I got, I noticed that the fastest decrease was due to the least test amount I put in the box.

The red line, green line, and the purple line indicates the performance of Ca(OH)2 level of 5 grams in 2L water, 10 grams in 2L water, and 15 grams in 2L water accordingly. Meanwhile, we can see a greater decrease from the original CO2 level from the red line, showing that 5-grams-trial is the most effective one.

However, the test result cannot lead to a significant conclusion, because this is only an observation and there are various variables that may lead to the result.

1. As I researched yesterday, the Ca(OH)2 is slightly soluble. Therefore, ever since I mix the Ca(OH)2 in the water, they would gradually precipitated at the bottom of the container. While the 5 grams should be the most effective trial because the precipitated amount is the least, so there was still a large proportion of Ca(OH)2 effective in the container for use. I will try to find a way to stir it when the machine is running and sealed.

2. The initial CO2 level is not consistent (I couldn't make it consistent because I can't gather CO2 all together into the machine equally). Through the graph, we know that the decrease is exponential. Starting with a lower amount of CO2 may reduce the effect of the catalyst.