Science Buddies: "Ask an Expert"

Hi, I’m an 8th grade student and I’m thinking of a Science fair Topic, is “how does bleach concentration affect detection of blood on various surfaces” suitable for a science fair topic? I will be using luminal as the detector， but is there any way the variable could be measured, and what kind of surfaces should I use?

Moderator note: I've moved your post to the Life, Earth, and Social Sciences forum so the experts there can help you.

You could try a couple different surfaces such as hardwood, laminate, and carpet.

As for how to measure the variable, I would use the same amount of blood each time and try different concentrations of blood.

To measure, it might just need to be qualitative and not quantitative. You could try to take pictures of how strong the signal it.

Hello!

Try using the same amount of blood, with different amounts of bleach per trial. I suggest performing 3 trials per each volume of bleach, on each of the three materials the blood will be on (you can try using tile, bleach-cleanable upholstery: think similar to the material a couch cushion is made of, or a bedsheet). The independent variable would be the amount of bleach, and the dependent variable would be the detection of trace blood by the luminol.

Corresponding with my fellow expert's point, taking photographs instead of writing down numerical data may be more effective to explain your results for this experiment easily, to show the distribution of blood after using the bleach.

Keep in mind that luminol only shows the distribution of traces of blood in an area; it does not indicate the amount of blood present in that specific area.

Hope this helps, and let us know if you have any further questions!
-cnoonan180

Thank u so much!!!

I found an app called Science journal recommended here on science buddies that can measurent that can measure the brightness(EV) will that work out??

No problem!

I have seen a couple of videos of people using the app for measuring a variety of waves (predominantly light), and based on what I have seen the app should work for your project!

A side note: the app also has functions for measuring other types of waves such as sound or pitch, so definitely keep that in mind should you need another type of wave sensor for a project.

If you haven't already seen it, I've attached the link from Science Buddies that explains the app's functions and how to use it more in-depth:
https://www.sciencebuddies.org/blog/goo ... ?from=Blog

If you have any other questions feel free to ask!
-cnoonan180