Question

124 2. Write the balan 2. Write the balanced total reaction that would occur w neutralizes stomach acid (HCl(). occur when the antacid Alka-2 (Al(OH):) bet ionic reaction: H ) + OH(aq) - H30 3. What volume of fluid would be delivered from the bure meniscus moves from its initial location to its final location are milliliter units. Use the correct number of significant 118 ered from the buret shown in the figure if the on to its final location? The larger units shown correct number of significant figures. Initial location of the meniscus - mL Final location of the meniscus ml 4. What is the purpose of adding a substance like the modified methyl orange indicator to the partially neutralized HCl solution before the sodium hydroxide solution is added?

Answer 1

2. Balanced total reaction,

Al(OH)₃ + 3 HCl = AlCl₃ + 3 H₂O

3. Initial location of the meniscus= 0.4 mL.

Final location of the meniscus= 48.9 mL.

So the volume of fluid delivered= (48.9-0.4)=48.5 mL.

4. It is because all indicator changes color on the basis of pH of medium. And methyl orange changes color in the range of pH

(3.1-4.4). So methyl orange is added before addition of sodium hydroxide solution as weakly acidic solution is needed for colour change. Whereas after addition of NaOH solution the medium pH level may get increased beyond the color change region.

Pre lab:

1.a) The antacid and NaOH react with HCl.

b)moles of HCl used in the experiment

=(0.04933 L × 0.488 M)

= 0.024

c) total no of moles of HCl neutralised by antacid and NaOH is 0.24

d)no of moles of NaOH added during experiment

=(0.02933 L × 0.510 M)

=0.015

e)So no of moles of HCl neutralised by NaOH= 0.015

f)no of moles of HCl neutralised by antacid=(0.024-0.015)=0.009

g) 1.032 gram of antacid nutralise 0.009 mole HCl

So moles of HCl neutralised per gram = 8.72 × 10^-3