If mg a% caustic soda solution and ng a% dilute sulfuric acid solution are mixed and the litmus test solution is still purple, the numerical relationship between m and n is correct () A.m=n B.m > n C.m < n D. Inability to judge

If mg a% caustic soda solution and ng a% dilute sulfuric acid solution are mixed and the litmus test solution is still purple, the numerical relationship between m and n is correct () A.m=n B.m > n C.m < n D. Inability to judge

It is known from the problem that the litmus test solution is still purple after mixing m-gram a% caustic soda solution and n-gram a% dilute sulfuric acid solution. According to the principle that the litmus test solution turns red with acid and blue with alkali, and does not change color with neutral solution, the reaction is exactly complete:2NaOH+H2SO4=Na2SO4+2H2O80& nb.

It is known from the problem that the litmus test solution is still purple after mixing the a% caustic soda solution soda solution and n g a% dilute sulfuric acid solution. According to the principle that the litmus test solution turns red with acid and blue with alkali, and does not change color with neutral solution, the reaction is exactly complete:2NaOH+H2SO4=Na2SO4+2H2O80& nb.

The neutralization reaction often drops phenolphthalein solution as indicator, why not purple litmus solution? If in the neutralization test with hydrochloric acid dropping in sodium hydroxide, drop phenolphthalein solution in sodium hydroxide solution to make it turn red, and then drop hydrochloric acid until the solution is colorless, it means that the neutralization end point is reached. At this time, the color changes from red to colorless, that is, from deep to shallow, not from shallow to deep. So should the first floor answer be the other way around? The neutralization reaction often drops phenolphthalein solution as indicator, why not purple litmus solution? In the neutralization test by dropping hydrochloric acid in sodium hydroxide, the phenolphthalein solution is added to the sodium hydroxide solution to make it red, and then hydrochloric acid is added to make the solution colorless, indicating that the neutralization end point is reached. At this time, the color is changed from red to colorless, that is, from deep to shallow, not from shallow to deep. So should the first floor answer be the other way around?

The change of purple litmus test solution was not obvious.
But human vision is more sensitive to the change from shallow to deep than from deep to shallow, so the titration error is small when phenolphthalein changes color.

The change of purple litmus was not obvious.
But human vision is more sensitive to the change from shallow to deep than from deep to shallow, so the titration error is small when phenolphthalein changes color.