MR / Schenectady, New York. Schenectady High School (urban, public high school). Grade 10 chemistry lab. One of a series of photographs taken during a chemistry lab on the titration of an acid and a base. Students work with: an acid (solution of hydrochloric acid), base (solution of sodium hydroxide), a buret (or burette, laboratory equipment used to dispense precise amounts of solutions), and an indicator (phenolphthalein solution) which is added to determine the equivalent point, or neutralization. In this image, students gently swish the solution in the Erlenmeyer flask to which they have just added base while holding it over white paper to monitor the color change. ID: AJ-g10p. MR: AJ-g10p. ©Ellen B. Senisi