The Change Of Mass During A Chemical Reaction

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Introduction:

Many people have always wondered about the outcomes of chemical reactions. In the experiment, ‘The change of mass during chemical reactions,’ focuses on the change of mass during a chemical reaction. It is known that a chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products (Kotz, J. C., & Treichel, P. M. 2019, March 08). The objective of this experiment is to perceive if the mass of the Iron(III) Nitrate and Sodium Hydroxide in part A as well as the Antacid Tablet in water in part B will increase, decrease or stay the same. In part A, different chemicals will be mixed together to experience if there is a change of mass whether if it is an increase, decrease or if it’s the same mass. In Part B, a tablet will be placed on the scale beside the substance, and then dropped into the substance. When the visible reaction has stopped, the total mass of the cup and its content were measured and recorded. The group hypothesized that the mass will not be different during a chemical reaction. As stated in the Law of Conservation of Mass, mass can neither be created nor destroyed in a chemical reaction. Therefore, the amount of mass cannot change (Mott, V. (n.d.)

Purpose:

To find out if the mass is gained or lost during a chemical reaction

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Hypothesis:

The mass will not be different during a chemical reaction, and the mass of each reaction will stay the same. As stated in the Law of Conservation of Mass, mass can neither be created nor destroyed in a chemical reaction Mott, V. (n.d). Therefore, the amount of mass cannot change. Mass is only changed when energy is involved which can be lighting a candle.

Equipment and Materials:

  • Eye protection
  • Lab apron
  • Test tube
  • Tongs
  • 250 mL Erlenmeyer flask and stopper
  • 10 mL graduated cylinder
  • Balance
  • 100 mL graduated cylinder
  • Plastic cup
  • Dilute of
  • Sodium hydroxide, NaOH(aq)
  • Iron(III) nitrate, Fe(NO₃)₃(aq)
  • Antacid tablet

Procedure:

Make sure both eye protection and lab apron are placed under the face and around the waist.

Part A: Iron(III) Nitrate and Sodium Hydroxide

  1. An empty test tube with tongs should be practised by holding it and making sure it slides into an empty Erlenmeyer flask. The flask is sealed so that the test tube fits perfectly and so that the stopper is sealed tightly.
  2. 5 mL of Sodium hydroxide solution was measured and placed in the 10 mL graduated cylinder. Then, this solution was poured into the flask.
  3. Groups then received different volumes of iron(III) nitrate solution to pour into the small test tube. In this case, the volume was 5 mL
  4. The flask was tilted and the test tube was carefully placed in it.
  5. Groups had to make sure that the flask was sealed with the rubber stopper
  6. The total mass of the flask and its contents were measured and recorded.
  7. The flask is tilted slowly so that the two solutions are able to mix
  8. The total mass of the flask and its contents were measured and recorded
  9. The flask and all its contents were returned to the teacher so it could be disposed of.

Part B: Antacid Tablet in Water

  1. 50 mL of tap water was added to a plastic cup.
  2. an antacid tablet was taken out of its package
  3. The tablet and the cup of water were placed on the scale. The total mass of the cup, water, and tablet was then measured and recorded.
  4. The tablet was added to the water and observations were recorded
  5. When the visible reaction had stopped, the total mass of the cup and its content were measured and recorded.

Observations

Table

Reaction 1

Reaction 2

Predicted mass change: decrease, no change, or increase?

No change in the mass

No change in the mass

The initial mass of reactants container (g)

172.5g

99.6g

Final mass of products + container (g)

172.5g

99g

Change in mass (final-initial) (g)

0g difference

– 0.6g difference

The observed change in mass: decrease, no change, or increase?

No changes in the mass

Mass decreased

Observed class results: decrease, no change, or increase?

No Change

Mean= -0.08g

Median= 0g

Mode= 0g

Mass Decreased

Mean= – .009g

Median= 1g

Mode= -.6g

Physical Properties

Observations

Reactants+Properties

Change Of Colour

Opaque

Transparent

forms bubbles inside the water that you can see as it foams on the surface

Translucent

Clarity

Conclusion

After completing the procedure given, the results showed that the mass for part A had stayed the same and the mass had decreased for part B. It can be concluded that the mass can be gained, lost, or stayed the same during a chemical reaction. This was done by making sure all lab apparatuses and measurements were used correctly so that outcomes of mixing the chemicals would be correct. If the wrong amount of liquids were mixed together, the observations would change. If the wrong apparatuses were used, the results would not be correct. It can be concluded that if the rubber stopper was not sealed to close the flask, the mass could have changed or if the Antacid Tablet was broken up in pieces then placed in the water, the mass could have changed. It is very important that the procedure were followed properly so that the observations are correct.

The hypothesis that was made was partially correct. In part A, the mass never changed and stayed at 172.5g but, there was a change of colour, It was opaque, and it was transparent. The hypothesis that was made was correct for part A. For part B, it can be concluded that when the tablet was placed beside the water on the scale, it had a mass of 99.6g. When the tablet dissolved in the water and placed on the scale, it decreased in mass by .6g and had a mass of 99.0g. It formed bubbles inside the water that you can see as is foamed on the surface, it was translucent, and the mixture was clear. The hypothesis that was made for part B was incorrect. This is because there was a change in mass. When working on the Antacid Tablet in water experiment, the results were incorrect. The steps for the procedure were done incorrectly, which meant that the results were incorrect. When filling the cup with water, it was placed on the scale to measure its mass. After, when the antacid tablet dissolved in the water, it was set down on the scale. It was shown that the mass increased by 2 grams. Fellow classmates then informed many groups about their final answer which matched other groups results. The correct steps that were supposed to be followed were that the tablet and the cup of water were to be placed on the scale. Then, the total mass of the cup, water, and tablet were to be measured and recorded. After, when the visible reaction had stopped, the total mass of the cup and its content were measured and recorded.

It is important that the procedure is read correctly so that when your constructing the lab, zero mistakes are made. A suggestion that can be made to the lab is to take some tape and put the name of the apparatus on the material so that you’re not putting the chemicals in the wrong apparatus. Another suggestion that can be made is to prepare beforehand and get the right amount of liquid needed into the beaker or graduated cylinder so that your not spending lots of time to transfer liquid from one apparatus to another using a dropping pipette. This saves a lot of time.

Sample Calculations

Part A

  • Average= 0 + 0 + 0.03 – 1.6 + 0 + 0 + 0 + .1 + 0.01 + .1 + .2 + 0.2 = -0.96/12 = -0.08
  • Median= 0 + 0 + 0.03 – 1.6 + 0 + 0 + 0 + .1 + 0.01 + .1 + .2 + 0.2= 0+0= 0/2 =0
  • Mode= Og Occurs most often// 5 times

Part B

  • Average= -0.2 + -0.6 + 2.71 – .6 – .6 + 2.60 – .6 – .6 – 0.49 – 0.53 – .6 – 0.6= – 1.08/12 = 0.09
  • Median= -0.2 + -0.6 + 2.71 – .6 – .6 + 2.60 – .6 – .6 – 0.49 – 0.53 – .6 – 0.6= 2.60-.6= 2/2=1
  • Mode= -.6 occurs most often// 6 times

Analyze and Evaluate

Calculate and record the change in mass for each reaction. Note whether each change resulted in a decrease, no change, or an increase in mass.

  • Part A = 0g /// No change in mass
  • Part B =.6g /// Decrease in mass

(B) Compare your results from part A with other students’ results. Account for any discrepancies

(B) Change Of Mass ( Reaction 1 )

0g

0g

+0.03g

-1.6g

0g

0g

0g

.1g

0.01g

.1g

.2g

0.2g

(C) For part A, calculate and record the average change in mass for your class

(C) (Average) Mean= -0.08g

Median= 0g

Mode= 0g

(D) Compare your results from part B with other students’ results. Account for any discrepancies?

(D)

-0.2g

-0.6g

+2.71

-.6g

-.6g

2.60g

-.6g

-.6g

-0.49

-0.53

-.6

-0.6

(E) Compare your results in Part A with your results in Part B. Suggest a reason for the differences.

(E) When the tablet is fully dissolved in water, it undergoes a chemical reaction that produces lots of carbon dioxide bubbles or fizz. As the tablets dissolve, the sodium bicarbonate splits apart to form sodium and bicarbonate ions. (Buddies, S. 2013, August 29)

The antacid is a substance that when its reacted with water, it would typically release gas and produce carbon dioxide gas. That is why it sizzle when you put them in water. The loss of this gas makes the combined mass of the antacid and water goes down.

The mass of the Iron (III) Nitrate mixed with Sodium Hydroxide stays the same because of the rubber stopper. When the rubber stopper is placed on the flask, gas is not realised when a chemical reaction occurs. This is because the rubber stopper stops all gases to be realised and stays kept in the flask. If there were no rubber stopper when the chemicals mixed, the mass would of decreased.

(F) For Part B, calculate and record the average change in mass for your class

(F) (Average) Mean= – .009g

Median= 1g

Mode= -.6g

(G) Would the class results for Part B differ if the reaction were carried out in a sealed container?

(G) Yes, the results for part B would be different if the reaction were carried out in a sealed container. this chemical reaction forms a gas that may rupture the container or explode. Since the container ruptures or explodes, lots of gas releases which decreases the mass a lot. It decreases more than a container that is not sealed. When it explodes, liquid might exit the container or it might be evaporated which will also decrease the mass.

(H) Why would it be unsafe to conduct Part B in a sealed container

(H) It is unsafe to conduct part B in a sealed container because the tablet and water undergo a chemical reaction that creates a gas. This gas will try to expand and may possibly cause the container to rupture or explode.

(I) How does the total mass of the products compare with the total mass of the reactants?

(I) Mass cannot be created or destroyed during a chemical reaction but is always conserved. The law of conservation of mass states that, during a reaction, the total mass of the product must be equal to the total mass of the reactant. (Mott, V. (n.d.)

(J) Compare your answers in (i) with your prediction. Account for any differences.

The prediction that was made was that for both parts of the experiment, was that the mass would stay the same and it would not change. When conducting the first part of the lab, it is concluded that the prediction that was made was correct. There wasn’t a change in mass and the mass stayed the same throughout part A. There were no differences in Part A, and the hypothesis that was made was correct. The answers in part A was the same as my prediction. There was a difference in part B when constructing the lab. It was found that there was a decrease of mass after weighing the tablet when dissolved in water. The prediction and answers to (i) were incorrect. There was a difference of -.6g for part B. There was a decrease of mass and the prediction and answers for (i) were not the same as the final results for part B.

References

  1. Buddies, S. (2013, August 29). Carbonation Countdown: The Effect of Temperature on Reaction Time. Retrieved from https://www.scientificamerican.com/article/bring-science-home-carbonation-time/
  2. Kotz, J. C., & Treichel, P. M. (2019, March 08). Chemical reaction. Retrieved from https://www.britannica.com/science/chemical-reaction
  3. Mott, V. (n.d.). Introduction to Chemistry. Retrieved from https://courses.lumenlearning.com/introchem/chapter/the-law-of-conservation-of-mass/

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