Final answer:
The product to mix with water to make invisible ink is baking soda (option B), which is invisible on paper until heated. Vinegar and baking soda produce a bubbling reaction that can clean drains but is not used for invisible ink. The pH rises towards neutral in this acid-base reaction.
Step-by-step explanation:
When invisible ink is mentioned in connection with a combination of a kitchen product and water, we are typically discussing a reaction that includes a substance that will remain invisible until it is subjected to a certain condition, such as heat. In this case, the original Arm & Hammer kitchen product that can be mixed with water to create invisible ink is baking soda (option B). When baking soda is mixed with water and applied to paper, it is generally invisible until the paper is heated, which causes a chemical reaction resulting in a color change that makes the writing appear.
Vinegar and baking soda, when combined, result in an acid-base reaction, producing carbon dioxide gas, water, and a salt. This bubbling reaction is not suitable for invisible ink, but it is excellent for cleaning applications, such as unclogging drains. Understanding that vinegar contains acetic acid and baking soda is a base (sodium bicarbonate), which neutralizes each other, is crucial for comprehension.
The pH of the solution, when vinegar is mixed with baking soda, will increase towards a neutral pH of 7 because the acidic vinegar is neutralized by the basic baking soda. The resulting invisible ink is due to the carbonic acid formed in the reaction; as the ink dries and is heated, it decomposes, leaving a mark.