Batteries are labeled: do not throw into the dustbin. What to do with the used ones?
What happens to unfinished soda? Many soft drinks are easy to tell apart by their tastes; they all are made from different recipes. But what they have in common is the presence of carbon dioxide. Compare the original acidity of soda with what happens to pH levels as the soda loses its carbonation and goes “flat”.
Fresh milk right from the cow has a pH value that is almost neutral. Gradually, however, milk becomes sour, even when it is stored in a refrigerator. In this investigation we will see if we can tell how many days old the milk is simply by measuring its pH. We will also investigate the microorganisms at work in its change in acidity.
Sometimes people preserve fruits by adding water, sugar, and some spice to make a fruit preserve, and then putting the preserve in a tightly sealed jar. But when fruit preserves are stored in a warm place, they start fermenting, which is a chemical breakdown by microorganisms like bacteria, and they get sour. What does this process have in common with the souring of milk?
Berries differ by the amounts of sugar and organic acids, such as citric acid and ascorbic acid (vitamin C). Which type of berry is the most acidic? Is it true that the more sour a berry, the lower is its pH? Working together in this investigation, we will find out.
To avoid problems with your teeth or your health in general, the pH of tap water you drink should be close to neutral. But what is the actual pH of the tap water you drink? Does the pH of tap water change over the course of the day? Does it change day by day? Or after a large rainfall or snowstorm?
Every citrus fruit contains organic acids, such as citric acid and ascorbic acid, also known as vitamin C. Yet limes or lemons taste quite acidic while oranges or mandarins are on the sweet side. Which among citrus fruits is the "world champion" in acidity? Is there a correlation between acid taste and pH-levels? Are there variations in pH for the same citrus fruit grown in various countries, regions or climate zones. Those questions will be explored in this activity.
When we look for answers in GlobalLab, we base our conclusions on data we all submit. But when we use probes and sensors, and since each of us uses our own instruments to collect data, how can we know whether our findings can be compared? How do we know our instruments even measure their target, in this case pH, or measure with comparable accuracy? What can be done so we can trust each other’s findings? For pH measurements scientists use a procedure called the calibration of pH probes. We check how accurately our probes and sensors measure pH by first measuring so-called ‘standard solutions,’ those with pH values we already know, since we either prepared them ourselves or purchased them from chemical catalogs.
Litmus, methyl orange, and phenolphthalein are well-known and broadly used acid-base indicators. But did you know that some plants can also be used as indicators?
How boring is sitting in the class! Today everything is like it was yesterday..., last week... last month... And if the lessons would be hold in museums - do you like the idea?
Some plants can tell us much about an ecosystem. These are bioindicators. Let’s see how reliable and universal they are.
As we breathe, we exhale CO2. Can CO2 accumulate in closed environments like classrooms? Might air quality drop over the school day? Let’s find out.
In this collaborative global project, classrooms collect data on a local STEM career they feel is important to their community’s future and contribute its details to a global database. Students are encouraged to consult the growing database and explore careers in their community, region, or world that align with their passions or interests.