An experiment was carried out as described below. The sodium hydrogencarbonate was added to __________ the mixture. What word completes this sentence?

In the context of an experiment involving sodium hydrogencarbonate, the word that completes the sentence is likely "neutralize." Sodium hydrogencarbonate, also known as sodium bicarbonate or baking soda, is a weak base commonly used in chemical reactions to neutralize acids.

When sodium hydrogencarbonate is added to an acidic mixture, it reacts with the acid, producing carbon dioxide gas, water, and a salt. This neutralization reaction can help to stabilize the pH of the mixture, making it less acidic and closer to neutral (pH 7). This property of sodium hydrogencarbonate makes it useful in various laboratory and culinary applications, as well as in antacid formulations to relieve indigestion caused by excess stomach acid. In summary, sodium hydrogencarbonate is employed to "neutralize" the mixture in the experiment.