Acids and Carbonates

Today in science we learned about acids and carbonates. We worked in pairs to combine different substances and recorded our observations on a table in a shared document on Google Drive.
Here are the substances we had: washing powder, chalk, lemon juice, eggshells, orange juice, tea, sugar, vinegar, baking powder.

We experimented and observed, recorded and checked. Then we were able to decide what happened when we mix an acid and a carbonate - they make gas! We knew this because all the acid and carbonate mixtures bubbled or fizzed (although the eggshells didn't work well - we think they needed to be ground up more than we could manage) showing the gas that was created.
Here is Jakob's diagram of which substances were acids and which were carbonates:

Can you spot the two tricky ones that were neither an acid or a carbonate?!