Stoichiometry of silver nitrate and sodium chloride PDF

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Stoichiometry of the Reaction of Silver Nitrate and Sodium Chloride The stoichiometry of a chemical reaction is the quantitative relation between the amounts of reactants and products in a reaction. This is based on the numbers of moles of reactants and products involved in the reaction. The word “stoichiometry” is derived from two Greek words-stoicheion (meaning “element”) and metron (meaning “measure”). If the stoichiometry of a given reaction is known the amount of product to be produced can be calculated knowing the amount of reactant reacting. Consider the following example: How much HCl will be produced if 4.0 g of H2 react with an excess amount of Cl2? The balanced chemical equation for this reaction is (1)H2 + (1)Cl2 = 2 HCl. According to this balanced equation 1 mole of H2 will react with 1 mole of Cl2 to produce 2 moles of HCl. Since there is an excess of Cl2 the answer depends only on the amount of H2 reacting. The only number connection between H2 reacting and HCl produced is given by the mole related balance chemical equation. Therefore, the amount of hydrogen needs to be converted into moles using the molecular mass of H2, 2.0 u. 4.0 g H2 x = 2.0 mole H2 1.0 2 2.0

2

Knowing the number of moles of H2 reacting and the mole relationship between H2 and HCl the number of moles of HCl produced can be determined.

= 4.0 mole HCl

2.0 mole H2 x

2.0 1.0 2

Knowing the number of moles of HCl produced the number of grams of HCl produced can be calculated using the molecular mass of HCl, 36 u.

4.0 mole HCl x

= 144 g HCl (140 g HCl to 2 significant digits) 36 1.0

What is the percentage yield for this process if 130 g of HCl are actually collected? (

% yield =

)x 100 =

(

ℎ

)

130

x 100 = 93 % =

140

The purpose of this experiment is to use the stoichiometry of the AgNO 3/NaCl reaction to predict the amount of AgCl compound that will be produced by the reaction (1) AgNO3 (aq) + (1) NaCl(aq)

______

> (1) AgCl(s) + (1) NaNO3(aq)

and to test that prediction experimentally

1|Stoichiometry of AgNO3and NaCl

Procedure: 1) Record the mass of a piece of weigh paper on your data sheet. Carefully add 0.20-0.22 g of sodium chloride, NaCl, and record the combined mass on your data sheet. 2) Carefully transfer the NaCl to a clean, dry 250-ml beaker. 3) Measure 20 ml of distilled water in a graduated cylinder and add the water to the beaker to dissolve the NaCl with a glass stirring rod. 4) Add 20 ml of 0.5M silver nitrate, AgNO3, solution to the beaker and mix well. This will contain an excess amount of AgNO3 to react with the measured NaCl and will not affect the amount of AgCl produced by the reaction. Let the beaker and precipitate sit in your closed locker drawer for 5 minutes, silver is light sensitive and this will also the crystals to increase in size. 5) Weigh a piece of filter paper and watch glass together and record the combined mass to the nearest 0.001 g. 6) Place the pre-weighed filter paper into the Buchner funnel; dampen it with distilled water from your wash bottle, then turn on the vacuum suction. Pour the solution and precipitate carefully over the filter paper, and be sure to rinse the beaker well with your wash bottle to get all of the precipitate into the funnel. Wash the precipitate with 20 ml of distilled water, and then wash with 15-20 ml of acetone to remove as much remaining water as possible. Leave the suction on for 5 minutes after the filtration is completed to begin the drying process by pulling air through the precipitate and filter paper. Use a spatula to transfer the filter paper and precipitate to the pre-weighed watch glass. 7) Place the precipitate, filter paper and watch glass in the oven (40-50°C) for 20-30 minutes to complete the drying process. Then remove from oven, cool to room temperature, and weigh to the nearest 0.001 g. Record this result on the data sheet. 8) Clean up the Buchner funnel and filter flask, the solution that was filtered through goes into the liquid waste, wash and dry the funnel and rinse the filter flask, return to set up as it was when you arrive for other students to use. 9) Complete the calculations on the report data sheet.

Liquid waste from filtering goes into the liquid waste bottle in the waste hood. The silver chloride and filter paper go into the solid waste beaker located in the same hood!

2|Stoichiometry of AgNO3and NaCl

Name______________________________

Stoichiometry of the Reaction of Ag

+1 (aq) and NO3 -1 (aq)

1) Mass of NaCl and weigh paper

g

2) Mass of weigh paper

g

3) Mass of NaCl used for reaction

g

4) Mole of NaCl reacting

mole

5) Mole of AgCl predicted to be produced

mole

6) Calculated mass of AgCl predicted (theoretical yield)

g

7) Mass of collected AgCl, filter paper & watch glass

g

8) Mass of filter paper & watch glass

g

9) Mass of AgCl collected after reaction (actual yield)

g

10) Percentage yield

%

Show all calculations:

3|Stoichiometry of AgNO3and NaCl...