Mystery Substances

As part of the Year 10 Science “Food” Assignment the students have been learning about acids and bases, including their characteristics. Students used their new knowledge to write compare and contrast paragraphs (see examples below). Last week the students nationally were getting stuck into a practical activity to learn how to test for acids and bases and identify pH values. They were given the equipment and mystery substances, and clear instructions. Below are pictures of the Nelson students who were excellent Scientists in the laboratory – working safely and efficiently to follow their worksheets and be able to draw conclusions using the evidence they had collected.

“Acids and bases are very different to each other. Acids are things like citrus, vinegar and tomatoes etc. They contain hydrogen ions which are written as H+. Acids are at the lower end of the pH scale from numbers from 1 to 6. If something is largely acidic it can be dangerous and harmful. In contrast, bases are substance that neutralize acids. They can damage or destroy other substances that they come into contact with. They contain hydroxide ions which are written as OH-. Bases are at the higher end of the pH scale and usually are numbers 8-14. Some bases are baking soda, bleach, and soap. You might have made a volcano before. To get lava you mix baking soda with vinegar which forms a sort of foam. This is baking soda which is a base and vinegar which is an acid forming a chemical reaction. Acids and bases in a sense work together. Acids produce hydrogen and bases accept the hydrogen. Acids and bases are important as they are involved in simple day to day things. Having these two substances is vital as they keep one another balanced.”

“Acids and bases are not the same. For example, acids are in foods such as lemon juice and vinegar. Bases are in things such as baking soda and bleach. Acids have more hydrogen ions and they produce hydrogen Bases have more hydroxide ions than hydrogen ions. The ph scale has different colours and helps us find the acids and bases of different things. in the middle of the pH scale it is green with the things that are neutral. On the left it is red with the acids and on the right it is dark blue which is bases.”