Why is it that NaCl and MgCl2 are both shown as acidic with different indicators but they are actually neutral?

Answer 1

Beats the snot out of me. Because you're using a crappy indicator? Because you're using crappy water?

Okay, so I can explain magnesium chloride: it's because hydrochloric acid is a strong acid and magnesium hydroxide is not very soluble, making it a weak base.

However, sodium hydroxide is a strong base and NaCl solution should be as close to neutral as makes no never-mind, provided you didn't start with water that was already acidic to begin with.

It's also possible that the indicator that you're using goes to the "acidic" color a little above pH 7, so true neutral solutions test as "acidic" even though they're not.