Chemistry Experiment #3

The purpose of this experiment is to: determine the density of an antacid tablet. determine the number of moles of acid neutralized by an antacid tablet. determine the molarity of the NaOH solution. determine the molarity of the HCl solution.

determine the number of moles of acid neutralized by an antacid tablet

If during Trial P, upon addition of only a few mL of NaOH the indicator changes color you should: add more indicator. add more water. stop titrating and determine the number of moles of NaOH added. add more HCl, reheat, and continue with the titration.

add more HCl, reheat and continue with the titration

What is the approximate molarity of the HCl used in this experiment. 0.002M 2M 5M 1M 10M

1 M

Which of the following is not a common active ingredient in commercial antacids? NaOH Mg(OH)2 CaCO3 NaHCO3

NaOH

The reaction: HCl(aq) + NaOH(aq) = NaCl(aq) + H2O(l) is an example of a(n): gas forming reaction decomposition reaction acid-base reaction precipitation reaction

acid-base reaction

In this experiment, all the acid added is neutralized by: two different antacids. phenolphthalein and baking soda. an antacid and sodium hydroxide. an antacid and phenolphthalein.

an antacid and sodium hydroxide

A back titration is used in this experiment. This is because: many antacids contain more than one active ingredient. we want to introduce repipets into the laboratory. we want to make the lab more difficult. the lab manual says so. the antacids are too soluble in water for direct analysis.

many antacids contain more than one active ingredient.

How is the number of moles of acid neutralized by the antacid determined in this experiment? moles of acid added - moles of acid remaining. equal to the moles of NaOH added. moles of acid remaining - moles of acid added. it is written on the label.

moles of acid added - moles of acid remaining

To determine the number of moles of acid that were initially added to the Erlenmeyer divide the molarity of the HCl by the volume in Liters of HCl added. multiply the molarity of the HCl by the volume in Liters of HCl added. divide the molarity of the HCl by the volume of HCl added. multiply the molarity of the HCl by the volume of HCl added.

multiply the molarity of the HCl by the volume in Liters of HCl added

In reading a buret, you should always: read the bottom of the meniscus. read the top of the meniscus. read the middle of the meniscus. read the edge of the meniscus.

read the bottom of the meniscus

In this experiment what do you use to dispense the acid into the Erlenmeyer flask? a buret a beaker an eye dropper a repipet

repipet

When the tablet has reacted completely with the acid, the remaining solution will be clear. some inert binder will remain in the flask. the solution may be cloudy. some inert binder will remain in the flask and the solution may be cloudy. the remaining solution will be clear and some inert binder will remain in the flask.

some inert binder will remain in the flask and the solution may be cloudy.

When the phenolphthalein changes color, then: the volume of NaOH added is equal to the volume of acid present. you have added the wrong reagents. the amount of NaOH added is just sufficient to react with all the acid present. the number of grams of NaOH added is equal to the number of grams of acid present.

the amount of NaOH added is just sufficient to react with all the acid present.

The purpose of Trial T is: to precisely determine the end point. to get an idea of the expected end-point and the amount of HCl to add in subsequent trials. to determine the active ingredient in the antacid tablet. to make sure that the HCl is strong enough to react with the tablet. to neutralize the NaOH

to get an idea of the expected end-point and the amount of HCl to add in subsequent trials.

An antacid tablet was dissolved in water and 10mL of 0.16M HCl was added. After the acid had reacted with the tablet it required 40mL of 0.02M NaOH to neutralize the HCl that remained. How many grams of HCl (Molar Mass = 36.5 g/mol) did the antacid neutralize? 0.029 2.2x10-4 2.2x10-5 0.29

0.029

When the following chemical equation is balanced: __Mg(OH)2(s) + __HCl(aq) = __MgCl2(aq) + __H2O(l) The stoichiometric co-efficients are: 1,1,1,1 2,1,2,1 1,2,1,2 2,1,1,2 1,2,2,1

1,2,1,2

An antacid tablet was dissolved in water and 10mL of 0.16M HCl was added. After the acid had reacted with the tablet it required 40mL of 0.02M NaOH to neutralize the HCl that remained. How many moles of HCl were initially added to the antacid? 1.6x10-3 1.6 1.6x10-2 16

1.6x10^-3

An antacid tablet was dissolved in water and 10mL of 0.16M HCl was added. After the acid had reacted with the tablet it required 40mL of 0.02M NaOH to neutralize the HCl that remained. How many moles of HCl did the antacid neutralize? 0.8 8.0x10-4 8.0x10-3 8

8.0x10-4

An antacid tablet was dissolved in water and 10mL of 0.16M HCl was added. After the acid had reacted with the tablet it required 40mL of 0.02M NaOH to neutralize the HCl that remained. How many moles of NaOH were required to neutralize the HCl that remained after it had reacted with the tablet? 0.8 8.0x10-3 8 8.0x10-4

8.0x10-4

When you react hydrochloric acid and sodium hydroxide you get: a salt and water. a precipitate. a gas and water. an explosion.

a salt and water