Answer:
When sodium hydrogen carbonate (also known as baking soda) reacts with lemon juice (which is acidic), a chemical reaction occurs. The expected observations and the explanation for each observation are as follows:
1. Effervescence (bubbling): As the lemon juice (citric acid) reacts with sodium hydrogen carbonate, carbon dioxide gas is produced. This gas escapes as bubbles, leading to effervescence. The reaction can be represented as follows:
Sodium Hydrogen Carbonate + Citric Acid → Carbon Dioxide + Water + Sodium Citrate
2. Release of a citric-like odor: When citric acid from the lemon juice reacts with the sodium hydrogen carbonate, it forms sodium citrate, which has a fruity odor similar to citric acid.
3. Change in color or formation of foam: Depending on the specific lemon juice used, there might be a color change or the formation of foam due to the interaction between the citric acid and the baking soda. This observation can vary depending on the concentration of the lemon juice and the amount of baking soda used.
4. No further visible change: Once the reaction is complete, there will be no other visible changes. The carbon dioxide gas produced during the reaction will dissipate into the air, and the solution will reach a new equilibrium.
Overall, the reaction between sodium hydrogen carbonate and lemon juice is an acid-base reaction, resulting in the production of carbon dioxide gas. This reaction is commonly used in baking to create a leavening effect and make baked goods rise.