Some Metals Are More Reactive Than Others

Aim: The aim is to find out the way five metals; iron, aluminum, magnesium, copper, zinc react when immersed in hydrochloric acid (HCl) and rate their reactivity ranking from the most to the least reactive.


Variables:

Types of variable
What is changed/ measured/ controlled?
How is it changed/ measured/ controlled?
Independent
The independent variable of this experiment is the types of metal.
Five types of metal are being experimented on, including iron, aluminum, magnesium, copper and iron.
Dependent
In this experiment, the reactivity strength of all 5 metals when immersed into hydrochloric acid (HCl) will be measured.
Observe and judge the size of the balloons placed on the test tubes – each of which will be containing one of the types of metal and HCl and determine which balloon has expanded the largest within the period of 1 minute. The larger the expansion of the balloon, the stronger the reaction of the metal when immersed into HCl.
Controls/constants
1. Amount of metal tested on
2. Equipments/apparatuses
3. Amount of hydrochloric acid contained within each of the 5 test tubes.

1. The amount of each type of metal will be measured using an electric scale. All experiments should using 0.8 grams of powdered metal.
2. The same size of test tubes, size of scale and size of balloon will be used for all types of metal.
4. With one’s eyes, one should be estimating the level of the hydrochloric acid so that it will fill up approximately 3 centimeters of all 5 test tubes.


Hypothesis:
If iron, magnesium, aluminum, copper and zinc were all immersed into hydrochloric acid (HCl) then the ranking from the most reactive to the least reactive would be zinc, copper, iron, aluminum, magnesium because the larger the atomic number of an element, the more electrons it has, meaning that it has got the largest number of shells, therefore, it’s valance electrons will be further from the positive attraction of the nucleus and therefore can be easily leave their orbits and react with other atoms.

Equipment and Materials:
· 0.8 grams of powdered iron
· 0.8 grams of powdered aluminum
· 0.8 grams of powdered magnesium
· 0.8 grams of powdered copper
· 0.8 grams of powdered zinc
· 25 Ml of Hydrochloric acid (HCl)
· 5 test tubes
· 5 balloons
· Petri dishes
· A graduated cylinder
· An electronic scale
· A spatula
· A camera
· A pipette

Method:
1. Gather all required materials.
2.
Read through the method and design an observation table that is able to record all observations.
3.
Place an empty Petri dish onto the scale and set it to 0 so that the Petri dish will not be weighed along with the metals.
4.
Using a spatula, scoop up powdered magnesium from its container onto an empty Petri dish.
5.
Place the Petri dish that has just been filled with magnesium powder onto the scale for weighing. It should weigh 0.8 grams. If it does not weigh such amount, adjust the amount of magnesium by either removing or adding magnesium powder to the Petri dish until it does weigh such amount.
6.
Measure 5 Ml of hydrochloric acid using a graduated cylinder and pour it into a test tube.
7.
Using the same spatula as before, removed all magnesium power from the Petri dish and into the test tube that has been filled with hydrochloric acid.
8.
Secure a balloon onto the test tube by stretching the opening of the balloon and fitting it onto the opening of the test tube.
9.
Observe the motions of the balloon (how much it is stretching).
10.
Record all observations seen during the experiment onto the observation table and video record and/or take photos of any major reactions.
11.
Repeat steps 3 – 10 for iron, copper, aluminum and zinc using a different test tubes, and Petri dishes. Graduated cylinder must be cleaned with water.
12.
Compare the size of the balloon on top of each test tube and conclude in the conclusion section of the observation table the metal that is most reactive to hydrochloric acid (HCl).

Observation Table:

Observations of the reactions of the five powdered metals; iron, aluminum, magnesium, copper, zinc when immersed into 5ML of hydrochloric acid.
Different kinds of metals
Qualitative observations of the reaction within the test tube
Qualitative observations of the balloon
Iron
- Iron sank to bottom immediately
- Many small bubbles rising to top
- Liquid is translucent
- Less bubbles appeared after 10 minutes.

· Balloon inflated a little at opening
· The slim part of the balloon is slightly standing up
Magnesium
- A lot of bubbles fizzle within the test tube
- Magnesium sank down to bottom
- Test tube feels a lot warmer
- The liquid inside test tube is translucent
- Less bubbles are visible after 20 minutes

- Balloon inflated quite big
- Balloon stood up

Copper
- Copper powder clumped up and sank down to bottom, some floated on top
- After 10 minutes, all copper sank to the bottom
- No bubbles visible
- Liquid is clear and transparent
- Copper is not diffusing

- Balloon did not inflate at all and stays deflated
- Balloon hangs down the test tube

Aluminum
- Aluminum powder sinks down gradually
- Stays mostly on top of HCl
- Some powder sinks to bottom
- Very little bubbles visible
- Aluminum is silver
- HCl is translucent with some silver flakes of aluminum

- Balloon barely inflated at all
- Very little air at the opening
- Balloon hangs down

Zinc
- Half sank to bottom, the other floats on surface of HCl
- Some bubbles rising

- Balloon inflated slightly but did not stand up
- The slim part of balloon stood up slightly


Diagram of Apparatus:
DIAGRAM OF MATERIALS AND EQUIPMENTS INVOLVED IN THIS EXPERIMENT.
Capture.JPG

Conclusion:
1. Answer the aim with a sentence and summarizing your data:
According to the data collected, one could see that the rank of the five metals from most reactive to least reactive would be magnesium, zinc, iron, aluminum and lastly, copper.

2. How accurate was your hypothesis:
Metals
Ranking of the metals’ reactivity according to the hypothesis
Ranking of the metals’ reactivity according to the result
Iron
3
3
Magnesium
5
1
Aluminum
4
4
Copper
2
5
Zinc
1
2

According to the outcome of the experiment, the hypothesis was not very accurate. This was because, as shown through the table above, none of the metals fitted into the ranking that they were predicted to be in as recorded in the hypothesis.
3. Where possible, compare the results to published data and/or theories:
When compared to the published data in the article “Metals – Reactivity Series”, one could see that there are some similarities because the information within the article and the result seen through this experiment. The article shows that from the five metals included within this experiment, the ranking for their reactivity from strongest to weakest would be Magnesium, Aluminum, Zinc, Iron, and Copper. This article proves part of this experiment’s outcome as they both show that Magnesium is the most reactive out of all the 5 metals and Copper is the least reactive out of them all. However, this data does not support the ranking shown through the experiment for the other 3 metals.

4. Explain the conclusion scientifically:
The reactivity of a metal would depend on some of its physical properties. One of the factors that affect the metals’ reactivity would be the amount of shells they have. This is because the larger the amount of shell an atom has, the further its valence electrons would be from the nucleus – the source of the positive charge. Therefore, the force of attraction between those electrons and the nucleus would be weaker because of the further distance, meaning that it is easier for its valence electrons to fall off and react with other atoms. However, in contrast, if an atom has a small amount of rings, its valence electrons would be closer to the positive charge and hence, they will also be more attracted to the nucleus and less likely to leave. “We already know that the negatively charged electrons are held in orbit by their attraction to the positively charged nucleus. This force of attraction decreases considerable as the distance from the nucleus increases. Therefore, electrons that are more distant from the nucleus are held less tightly and are more easily lost that are electrons closer to the nucleus.”(Chemical Reactivity)
.
Another thing that determines the reactivity of a metal is its position on the periodic table. Elements that are closer to the Noble Gases column (group 8) are more likely to strongly. “The closer the element is to be a stable octet, the more reactive that metal will be” (Law). In this experiment, since magnesium is closest to becoming stable and obtaining a stable octet, it should be most reactive, which is also what the outcome of the experiment had shown.

Evaluation:

1. Reliability –
The data received through this experiment is not very reliable as the experiment was only carried out once and therefore the final result may not be very accurate.

2. Validity –
The method of collected the results of this experiment is not valid because although it related to the aim, allowed the one to obtain results that enable one to answer the aim and made the independent variables change, it still did not controlled all the constant variables. Therefore, there are many weaknesses in the method that could impact the accuracy of the results, making it invalid.
Weaknesses and Improvements –
Weaknesses
Improvements
The test tubes did not contain exactly 0.8 grams of solid. This is since the process of pouring made some of the metal powder spill out and therefore there was less metal than there should be.
In order to improve this weakness, one could use a funnel to help pour the metals into their test tube.
As there were no time limits to observing the metals, there may have been some metals which were observed much longer than others, as the experiments began at different times but ended at the same time.
A stop watch should be used to indicate the amount of time each reaction should be observed for, making the test more fair and accurate.
The process of pouring the powdered metals into the test tubes was time consuming, as one had to be careful to spill as little solid as possible. Also, the balloon took some time to put on. Therefore, during this process, some gas may have escaped even when the balloon had not been placed over the test tube yet, impacting the accuracy of the result seen.
In order to improve this weakness, one could use the funnel as it would not drop the powdered metal and therefore make the process less time consuming. In addition, as one person does this, another person must be ready to immediately place the balloon onto the opening of the test tube as the pouring process is completed.

3. What made this a fair test?
This experiment was a fair test since all the independent variable were being changed and some of the constant variables were controlled. However, there is still more than one constant variable. The fact that not all the constant variables were controlled is proven through the weaknesses above. For example, one of the constant variables stated that one must be using the same amount (0.8 grams) of each metal. However, according to the weakness, the type of metal was not the only thing that changed, but the amount of each metal was also different. Therefore, this experiment has some qualities of a fair test but cannot be considered as a completely fair test.

Work Cited:
· "Chemical Reactivity." Science by Jones. N.p., n.d. Web. 17 Dec. 2009.
<http://www.sciencebyjones.com/chemical_reactivity.htm>.
· "Metals - Reactivity Series." Slide Share. N.p., n.d. Web. 17 Dec. 2009.
<http://www.slideshare.net/Arrehome/metals-reactivity-series>.