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May 6, 2016

Homework Help: Chemistry

Posted by T on Saturday, December 1, 2012 at 4:43pm.

Antacid tab is dissolved in water and a few drops of phenolphthalein is added yielding bright pink solution. 0.2025 M HCl added until pink color disappears. The 0.2147 M NaOH added until it turns light pink for ~30 seconds.
mass on antacid tablet = 1.056g
initial V 0.2025 M HCl = 1.97 mL
final V of 0.2025 M HCl = 42.26 mL
initial V of 0.2137 M NaOH = 0.89 mL
final V 0.2147 M NaOH = 17.32 mL
How many millimoles of acid are neutralized per antacid tablet and per gram of antacid tablet?
So I have 40.29 mL HCL used and
16.43 mL NaOH used.
I don't know where to go from there.
• Chemistry - DrBob222, Saturday, December 1, 2012 at 4:58pm

millimols HCl initially = M x mL = ? = mmols to more than neutralize the antacid.
mmols NaOH added to neutralize the excess HCl = M x mL = ?
mmols HCl - mmol NaOH = mmols HCl used to neutralize the anacid tab. That answers the first question.
The second is mmols HCl/1.056g = ? which gives the second answer.