Science Buddies: "Ask an Expert"

i am doing the mentos experiment (why do mentos mixed with soda produce an eruption? & do not know what kind of charts or graphs i should use.

nhpstormcats wrote:i am doing the mentos experiment (why do mentos mixed with soda produce an eruption? & do not know what kind of charts or graphs i should use.

What is your hypothesis? Once you decide what that is, then you can create a test to check this. Here are some sample questions that might help you develop a hypothesis. For example, will any candy work? Will any sugar candy work? Do you need a certain number of mentos per liter? Will plain sugar work? How much?

I don't know what grade level you are in, but this may be pretty difficult to do rigorously... by that I mean it is difficult to measure things relating to this experiment (like how much gas is released). So then the project becomes too simple for many students since the only thing you can "measure" is "yes/no" for did it explode.

Louise

My son did this experiment for his science fair last year. As Louise said, it is very hard to do this experiment rigorously. But it is possible, and is a very neat experiment when done correctly.

Start step by step. What is your hypothesis? What is your research question? What grade are you in? What are you planning to measure, and how do you plan on measuring it?

This is one of those classical deceptively difficult experiments. It is very easy to design an experiment that proves absolutely nothing. Looks great, but provides no science.

That being said, the true science behind the phenomenon is truly fascinating, and CAN be measured accurately.

I'm in 6th grade. The title of my project is Why do mentos mixed with soda cause an eruption? So wouldn't this be my hypothesis? I was thinking of adding a chart showing the reaction of different candies when mixed with soda.

OK. Your hypothesis is your tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation. In simpler words, what you think will happen when you run your experiment.

A hypothesis is a statement / explanation, not a question.

So why do you think Mentos and soda (BTW, it's not every soda) causes an eruption? The answer to this question will become your hypothesis. You then need to come up with an experiment to test your hypothesis (to see if your guess for the reason is correct or not.)

If you had a chart with different candies mixed with soda, you wouldn't be explaining Mentos, would you? You might be showing the effect of different candies on the eruption of soda. That is a different question.

You should start at the beginning. There is a very good explanation of the scientific process involved in doing a science fair experiment on this web site. Here's the direct link:

https://www.sciencebuddies.org/mentorin ... ndex.shtml

I would suggest reading this to see what is involved in doing a science fair experiment. I'm sure, also, that your teacher has provided you with guidelines. Those will be the ones you need to follow.

Once you have read this, check back with how you would like to modify your hypothesis, research question, and how exactly you plan on testing your hypothesis. The experts here would love to provide you whatever guidance you need.

This is a pretty cool experiment once you get going.

How about why do mentos foam when dropped in soda & I could use like acid drinks like oj, flat soda anything non carbonated. BTW in my reasearch so far it says it work even with reg soda u won't get the same effect though.

nhpstormcats wrote:How about why do mentos foam when dropped in soda & I could use like acid drinks like oj, flat soda anything non carbonated. BTW in my reasearch so far it says it work even with reg soda u won't get the same effect though.

Well, as I said, it is easy to do this trivally but hard to do it well. Comparing fruit juice and mentos with soda and mentos shows what? Carbonation is important? This goes back to what I said before... there is nothing to measure except yes it foams or no it doesn't.

What happens when you put mentos in to coke? What physical process leads to the release of the carbonation?
What is the difference between diet coke and regular coke? What is the different between the different flavors of mentos? (And there is a difference!)

Louise

Is this for a science fair experiment? If so, what are the rules you need to follow?

If you want to look at why mentos foam when dropped in soda, you need to think of what it is in the soda, or what is special about Mentos that makes this happen so violently.

Have you read the web site regarding how to do a science fair experiment? There is a method as to how science is done. You need to work using that method. It's about doing research on a topic, choosing a research question that you want to answer, formulating a hypothesis as to what you think your experiment will show, and then running the experiment in a way that provides results to prove or disprove your hypothesis. Finally, analyzing the results you obtained and making conclusions from them.

This all occurs one step at a time.

As Louise said, this is hard to do well with Diet Coke and Mentos. Once you do your own research, we can start to explain why that is. You need to start one step at a time.

Please read the web site and think of what question you would like to answer involving Coke and Mentos. Then post that question for us, and we'll let you know what we think of it, problems it might have, improvements you can make, or if we think it's just great. Then you move on to your hypothesis, experimental design, etc. Science really has to proceed in an orderly, logical fashion to be useful.

My son is conducting this experiment and I am his adult helper/videographer. His question is: "Do the number of divots in Mentos® affect the height of the stream when mixed with Diet Coke®? " We have a 2 story house and we have taped off 12 feet on the side of the garage. However, run #1 w/o any divets the stream went MUCH higher than 12 feet (and higher than the garage itself) Probably 18 - 20 ft. Wondering how others may have measured this experiment.

You can place a video camera at a distance from the soda bottle with a vertical yardstick next to the bottle but visible (or on the wall - it needs to be fully visible. Look at the frame of the video (printing it is easiest). The ratio of the height of the column of soda to the height of the yardstick x the actual length of the yardstick = the height of the column of soda.

Many other methods work too. There is some error in the above due to parallax, but this is a science fair.

Thanks for your response. This is however how we did it. We took a twine roll and measured off one foot sections and tied a pink ribbon at each foot interval. Then at the 5 foot intervals we tied a white ribbon. Then attached one end of the twine roll to a baseball and my son threw the baseball over a set of telephone wires. The top wire was approx. 25 feet tall. Secured the ends of the twine roll with bricks and measured viewing the videotape.
It worked however wasn't perfect. Would have been better to have a white background instead of the neighbor's trees. =)