"Исследовать — значит видеть то, что видели все, и думать так, как не думал никто". Альберт Сент-Дьерди
Группа учащихся МБОУ лицея №1 г.Цимлянска Ростовской области
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.
What if you measure the pH of a chilled solution that you just removed from the refrigerator, and somewhere else, others measured the pH of the same solution but at room temperature on a warm day? Does the temperature of a solution affect its pH? If so, what does this mean for our investigations into pH? Should we measure pH when the solutions are at the same temperature?
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.