Sodium Hydroxide, 0.1 M (0.4%), Aqueous, Laboratory Grade, 500 Ml

Exactly what I needed.

A lesson I do with children involves phenolphthalein, an acid, and a base. I was using ammonia for the base, but one step is improved if the base is clear rather than the cloudy look of ammonia. This product is sufficient to create the change that is the goal without being as caustic as other options. (I still keep the materials well away from the children.) Our experiment was successful!