Chemistry help, pleeease!

Question

Hydrochloric acid sodium hydroxide --> Water Sodium Chloride

1) How do you know when all the acid is neutralized?

Write the equations to represent formation of hydrogen gas.

(We used Hydrochloric acid, sulfuric acid, nitric acid, and acetic acid, and placed a magnesium ribbon inside, and put a burning splint into the mouth of the test tube.

Hydrochloric acid, sufluric acid, and acetic acid made the fire poof a little, and the nitric acid produced a yellow gas.)

Please explain asap, so i can understand in the future... thanks!

Answer 1

when you add NaOH drop by drop & stir,...

and phenolphthalein which was added to the mix just turns the lightest pink,... you are just a bit past neutral (maybe 1 drop past)

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Mg & 2 HCl --> MgCl2 (aq) & H2 (g)

Mg &  H2SO4 --> MgSO4 (aq) & H2 (g)

Mg & 4 HNO3 --> Mg(NO3)2 (aq) & 2 NO2 (g) & 2H2O

Mg &  2HC2H3O2 --> Mg(C2H3O2)2 (aq) & H2 (g)