barium sulfate product formation

7/28/2019 Barium Sulfate Product Formation

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Burhan Riaz

09/21/2011

Changing the Amount of Reactants and its Effects on the Product

Beginning Ideas:

In this experiment, we are given sodium sulfate and barium chloride. These two reactants will

form the following equation:

Na2SO4(aq) + BaCl2(aq) ----------> BaSO4(s) + 2NaCl(aq)

One of the products, barium sulfate, is a solid compound and can be easily measured on a weight

scale. By changing the amounts of the reactants, we can measure the mass of barium sulfate and

compare the results to see what kind of effect changing the reactants can have on the products. I

think the results we will see will correlate to what becomes the limiting reagent depending on

how much Na2SO4 and BaCl2 is put into the experiment.

Tests:

12 variations of reactants were tested in the experiment. Each lab group completed two tests by

reacting 1M Na2SO4 and 1M BaCl2 according to the given amounts. For each test, two 50mL

beakers were used. In each beaker, the appropriate amount of Na2SO4 or BaCl2 was administered

from the stock solution containers. A graduated cylinder was used to accurately measure the

amount of reactants. Both beakers were then put on a hot plate at a temperature before the

boiling point for twenty minutes. After twenty minutes, the solutions were slowly mixed into

another 50 mL beaker and were left on the hot plate for fifteen minutes. The mixture was given a

cool-down period of five minutes. At this point, a vacuum filtration system was set up and the

filter paper was weighed on an electronic scale. The contents of the beaker were poured into the


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vacuum filtration apparatus. The weight of the paper plus the BaSO4 were then measured on the

electronic scale. Data from all lab groups were compiled and theoretical calculations were made

as well as percent yields.

Observations:

Amount of Reactants(mL) and Products(g)

BaCl2 mL Na2SO4 mL Actual BaSO4 (g)

0.0 2.0 0.02

20 0.0 0.02

18 2.0 0.74

16 4.0 1.5

14 6.0 1.0

12 8.0 1.1

10 10 2.1

8.0 12 1.9

6.0 14 1.2

4.0 16 0.9

2.0 18 0.4

1.0 19 0.3

The precipitate came out as a chalky white color when vacuum filtrated.

Evidence:

Amount of Reactants(mL) and Products(g) compared to the Theoretical(g) and Percent Yields

BaCl2 mL Na2SO4 mL Throretical (g) Actual (g) Percent Yield %

0.0 2.0 0.0 0.02 NA

20 0.0 0.0 0.02 NA

18 2.0 0.5 0.74 148

16 4.0 0.9 1.5 167

14 6.0 1.4 1.0 71

12 8.0 1.9 1.1 58

10 10 2.3 2.1 91


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8.0 12 1.9 1.9 100

6.0 14 1.4 1.2 86

4.0 16 0.9 0.9 100

2.0 18 0.5 0.4 80

1.0 19 0.2 0.3 150

The theoretical value was calculated by the following formula when using BaCl2 as a reactant:

x mL BaCl2 x (1L/1000mL) x (1mol BaCl2/ 1L BaCl2) x (1mol BaSO4/ 1mol BaCl2) x (233.6g

BaSO4/ 1mol BaSO4) =

The theoretical value was calculated by the following formula when using Na2SO4 as a reactant:

x mL Na2SO4 x (1L/1000mL) x (1mol Na2SO4/ 1L Na2SO4) x (1mol BaSO4/ 1mol Na2SO4) x

(233.6g BaSO4/ 1mol BaSO4) =

The lowest amount of grams would be the theoretical value since it takes account that there is a

limiting reagent.

After the actual amount of grams has been found, we can do a percent yield calculation. This

equation will show how close the actual yield is to the theoretical yield.

actual (g)/ theoretical (g) x100 = Percent Yield.


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Claim:

According to the data, there seems to be a correlation between the amount ofNa2SO4 and BaCl2 on

the mass of BaSO4. If there was less Na2SO4 for example than BaCl2 for example, then Na2SO4

would be the limiting reagent. The limiting reagent is responsible for the amount of the product.

Reading:

The first step in predicting a chemical equation is to know the coefficients2. If there are no

coefficients, then the equation must be balanced out if it is not already done so. This can be done

by trial and error until the number of an element on the left side matches with its corresponding

element on the right side2. The solubility rules for ionic compounds should be referred to in this

particular equation of Na2SO4(aq) + BaCl2(aq)2. According to the textbook, Ba

2+when paired

with SO42-

, is insoluble2. The resulting equation is called a precipitation reaction

2.

When two reactants are mixed together, the amount of product will depend upon the amount of

each reactant1. If Na2SO4(aq) and BaCl2(aq) were added and all of BaCl2 was used up, Na2SO4

would be the excess reagent and BaCl2 would be the limiting reagent. The amount of BaCl2 is the

limiting reagent because a reaction after its complete use cannot occur1. Therefore, the excess

reagent doesn't contribute to the product once the limiting reagent has been used up. This

principle is the core of the experiment since we are changing the amounts of reactants to see the

effects on the product. To find the limiting reagent, the equation must be balanced to give the

correct mole-to-mole ration from product to reactant1. Once the moles of the reactants are found

out, one can simply multiply by the mole-to-mole ration to find out how much product would be

made from that particular reactant1. The least amount of product made from a reactant is the

limiting reagent1.


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Reflection:

A precipitation reaction took place just as we predicted after consulting the solubility rules of

ionic compounds in water. The best way to compare the results is the see it side-by-side by the

corresponding theoretical data. The graph displayed in the evidence section shows the theoretical

values as well as the actual data. The theoretical values forms a trend that is positive before a

point and negative after the same point. This "point" is actually the most amount of product that

was made in the experiment and involved 10mL of Na2SO4(aq) and 10mL of BaCl2(aq). It is

noticeable that the graph is perfectly symmetrical when looking the theoretical data. It's not a

coincidence that the amount of reactants is also symmetrical in nature. For example, 8mL

Na2SO4(aq) and 12mL BaCl2(aq) would make the same amount of product as 12mL Na2SO4(aq)

and 8mL BaCl2(aq). Since the values for the reactants are reversed and the same amount of

product is made, we are given a symmetrical graph. In the positive slope, the limiting regent is

Na2SO4 because there is less of it than BaCl2. In the negative slope, the opposite is true. What

this means is that the product is directly controlled by the limiting reagent. When both reactants

are set equal to each other by moles, the maximum amount of product can be made.

That being said, the actual data varied from the theoretical data. Some of the values were spot on

yet some actually looked highly inaccurate. One way that could fix this problem is to do multiple

trials and find an average. This may give us a graph more similar to the theoretical values. The

actual maximum somewhat corresponded to the theoretical maximum at 10mL of Na2SO4(aq)

and 10mL of BaCl2. Even though the values were different, it was still a higher amount of

product than any of the other combination of reactants. There seems to be a general positive

trend before the maximum point and a negative trend after the maximum point which correlates

with the theoretical data. A lot of human error was made and systematic errors also may have


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had an impact on the actual data. As a conclusion, we found out that limiting reagents are most

important in predicting the amount of product made.

News Brief:

Chemicals are used every day by us. From brushing our teeth to doing the laundry, we are

constantly being exposed to various chemicals throughout the day. Have you ever noticed that

sometimes your bathtub will sometimes have stains know as bathtub rings? These stains are

caused by certain chemicals reacting with one another. Water with positively charged chemicals

can react with soap to form these stains. That is why when washing clothes, detergents will

include chemicals that counteract the effect of positive chemicals like calcium or magnesium.

Some chemicals will be soluble in water or in other words it will blend in with the water. Some,

however, will form solids like the bathtub rings. To predict whether a reaction will form a solid

or not, one must consult a solubility chart that chemists have made.

The amount of the solid or product depends on the amount of the reactants. If there are let's say

two reactants, they will react to form the product. If there is less of one reactant, the other

reactant will be left over since it has less to react with. The least amount of reactant is often

called the limiting reagent and determines the amount of product that can be made. Finding the

correct amount of reactants to use is very important to creating your daily household chemical

products.


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Citations:

1Chemistry 2046L Laboratory Manual for Chemistry Fundamentals II

2Tro, Nivaldo J. Chemistry: a Molecular Approach. Upper Saddle River, NJ: Pearson Prentice

Hall, 2011. Print.

barium sulfate product formation

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