LAB: Some Metals Are More Reactive Than Others

Name______

Date______

Science 8

LAB: Some metals are more reactive than others

Testing the Reactivity of the 5 different metals Magnesium, Aluminium, Zinc, Iron, and copper in hydrochloric acid lab 4/13/2012

A. Title and date.

B. Aim

Design a fair test that will allow you to rank the 5 metals in order from the most reactive don’t to the one that is least reactive.

Design a lab testing the reactivity of the 5 metals, measuring the reactivity by using eyesight to estimate the most vivid reaction represented by fizzing, bubbles, fire or another reaction. The lab will be controlling the surface area ( how much of the material surface is exposed) , temperature, and agitation (. Rank the five metals in order from most reactive to least reactive), when they are combined with hydrochloric Acid. The reactions will be categorized by how powerful their reactions and then thereafter one will find out which is the most and least reactive.

C. Variables.

Variables of Reactivity lab

Identify the variable / Changed, Measured, Controlled
Independent Variable / The metals (Magnesium, Alumnium, Copper, Zinc, Iron) / How it will be changed?
The metals (1tsp of it as powder) will be changed by physical movement. The metals will be put into each their own test tube, where all the variables will remain the same except the metal.
Dependent Variable / The reactivity / How it will be measured?
Measure how much time it took for it for dissolve, measured with a stopwatch with seconds. The amount of fizzing, or bubbles as well the speed of it. This will be measured by eyesight.
Controlled
Variables/constants / Surface Area / How they will be controlled?
All of the metals will be in powder form.
Agitation / How they will be controlled?
There will be no agitation, the test tubes will stay in the test tube rack which won’t be moved either.
Temperature / How they will be controlled?
The temperature will be controlled by using a thermometer. The temperature will be room temperature; there will no touching the test tube (giving it warmth).
Hydrochloric Acid / How they will be controlled?
There will be 5ml of hydrochloric acid in each test tube; the amount will remain the same for each test tube.

Explanation:

The independent variable in this lab is the metals, Magnesium, Aluminium, Copper, Zinc, Iron. However these are all different metals and have difference such as weight, and flexibility etc. Therefore, in order to make it a fair test and ensure they all have the same surface area and are of the same form, it was decided that they were to be in powder form. This way they will all have almost the exact same surface area, and they will all be standardized. You can get the metals in powder form by either ordering from a supplier online for example http://www.metalpowders.com.au (Scroll down to the bottom to see citation) or using your own techniques in order to grind the metals to fine powder. By having them in powder form it means your results are much more accurate as well.

The independent variable is the reactivity, the reactivity is going to be measure via eyesight, the way it will be categorized is :

Very strong reaction: Maybe Explosion, fire, excessive fizzing and a lot of rapid bubbling, flows over the test tube

Strong reaction: There are many bubbles fizzing rapidly

Medium reaction: There are some bubbles fizzing, but not at a high speed

Small reaction: There are a few bubbles and a bit of fizzing,

Very small reaction: There is a bit of movement very few bubbles

No reaction visible.

The 3 controlled variables are as following, surface area, agitation and temperature.

Surface area has already been standardized, so that is quite controlled. The agitation just depends on how much you touch the test tubes and how much they are moved or if there was any stirring. In this lab however test tube’s won’t need to be moved so there is no risk of any agitation. The temperature would be the most difficult, because body heat, air around you, heat from your hands, sunlight etc. all these things can affect temperature you just need to make sure you don’t change anything, like you done open the door to the lab halfway. Other than that then the variables in this lab are very controlled and the results should be quite fair as well as accurate.

The reactivity and the levels

Temperature

Agitation

The hydrochloric acid

D. Hypothesis

If you add each of the 5 metals to the hydrochloric acid then according to my knowledge the 2 most reactive metals will be magnesium and aluminium and the 3 least reactive metals will be zinc, iron, and copper because the elements which are closest to the sides of the periodic table are more reactive, since it’s easiest for them to loose or gain valence electron depending on what side they are, which results in them being more reactive. The reactivity would be exposed as movement, strong scents, change of color etc. the more it changes the more reactive

Explanation

All metals react differently, some are seen all by themselves in nature while others are difficult to find just as their own element as they are very reactive and easily create compounds. The reason that magnesium and aluminium are the most reactive is because, take Magnesium for example, it is in the second column meaning that it only needs to get rid of 2 valence electrons in order to have a full valence shell. The elements are reactive according to how easy it is for them to have a full valence shell, for example it’s easier to gain one electron then it is to loose 3. However all metals react differently, and react differently to different elements and compounds depending on their electrons, how they bond etc.

The hypothesis can be tested by looking at how the different metals react. If Magnesium begins to excessively fizz and bubble rapidly whereas iron might just produce a few bubbles then it would be proven correct that, magnesium is more reactive than iron. The reactivity can be measured in many ways, like temperature, the gas output, bubbles etc. We chose to focus on the bubbles/fizzing and the movement in the test tube. For example if the liquid began creating many small bubbles making the entire liquid fizz it would prove the reactivity. Therefore, to prove the hypothesis correct then aluminium and magnesium would have the highest amount of bubbling and fizzing in comparison to the other three metals.

E. Equipment and Materials

- 5 test tubes

- 1 test tube rack

- aluminium, Magnesium, zinc, iron, copper in powder form (enough for there to be 1 teaspoon

- 1 teaspoon

- 1 knife or object with a blade (used to sweep off the metal, so there is exactly one teaspoon)

- 1 stopwatch

- 1 measuring cup

- 30 ml of Hydrochloric acid (5ml for each test tube)

- Thermometer

Explanation

The five test tubes for the experiment will be the same size; the same spoon will be used each time.

When doing the materials, remember that there will have be enough for 1 teaspoon, you can get extra if you might be clumsy. The blade used for removing the extra material from the spoon doesn’t have to be a knife; it just needs to be something a thin solid edge which will be able to sweep the material of the spoon smoothly. The stopwatch used, should be using seconds and milliseconds and the measuring cup is for measuring the ml’s.

F. Method

Take out the equipment and materials
Place the 5 test tubes in the test tube rack-
Take the funnel, stick the tip into the first test tube
Measure out 5ml of Hydrochloric Acid with a measuring cup
Pour 5 ml of Hydrochloric Acid into the funnel
Repeat steps 2-4 with all five test tubes
Clean and dry the funnel
Stick thermometer into one test tube at a time and record the temperature
Take one teaspoon of metal powder (this can be any of the 5 metals, there is no order)

10. Take the teaspoon and take the knife glide over the teaspoon, sweeping away extra material

11. Be ready with stopwatch

12. Place funnel into the first test tube and pour the first metal into the funnel

13. Start stopwatch

14. Watch the reaction and record the observations

15. Take a new metal and repeat steps 8-13 and continue till you have tested all 5 metals

Explanation

When you do this experiment you will start by taking out your equipment and your materials. When you place your test tubes, place them in the racket somewhere where there isn’t an AC or a door which might affect the temperature. Also when you have put them in the racket keep them in one place so you won’t be moving it around during the experiment, risking some agitation. The reason there is a funnel is because it will ensure that no material is spilled, and also remember to stick down into the test tube to be completely sure. Afterwards your pour up the acid and then you begin the process of measuring out the metals. However it’s very important that you clean and dry the funnels before you start pouring the metal powder into them. There might be some residue of the acid left in it, which could cause it to react in the funnel. Then you measure the temperature to ensure it’s all the same. Measuring out the powder will be done with a knife or something which can sweep away any extra material,

that way the amount will be exactly the same for every test tube. As soon as the metal powder has been poured down the funnel, you start the stopwatch. Now you begin recording the data according to the reactions, “very strong reaction, strong reaction, medium reaction, small reaction, very small reaction and no reaction visible”

G. Diagram of apparatus

Diagram of Reactivity lab

Explanation

Here it shows the setup of the experiment, you see the funnel and the teaspoon above it. The teaspoon is pouring metal powder into the funnel leading it down into test tube with 5ml of Hydrochloric acid. The stopwatch is on the side for the other person to start and stop, recording the time for the metals to dissolve. The thermometer is there as well, in order to check the temperature before adding the metal powder, in order to make sure that it is a fair test and that all the temperatures are the same.

Part two of lab

H. Presenting Data – Qualitative Observations

Trial 1

Trial

Aluminum

/ After 30 seconds there is no visible reaction. The aluminium just floats on top of the acid. There are droplets of acid that sit on aluminium.
No change at 2min.
Stopwatch stopped at 2 min. / After 10 seconds the acid turns pink. The aluminium just floats on top of the acid. There are droplets of acid that sit on aluminium.
No change at 2min, the acid is still a slight pink shade, however the acid is clear.

Stopwatch stopped at 2 min.

Magnesium

/ There is Immediate rapid fizzing and many small bubbles, the liquid is unclear with bubbles. The bubbles are jumping out, at about 1-2 cm, there is also some smoke rising slowly. After 8 seconds the acid reacts with the metal in a visible way, The black, on the metal turns more silver. At 1 min there is condensed liquid on the sides of the container. At 1.20 it smells like beer and smoke. At 2 min bubbles are smaller and the acid becomes clearer, the bubbles aren’t rising as fast.

Stopwatch stopped at 2 min.

Iron

There is no immediate visible change. There are little bubbles at 45 sec. the Bubbles are a bit larger 2 min.

Stopwatch stopped at 2 min.

/ At 50 sec there are small bubbles, which have appeared. At 1.30 some of the bubbles begin to rise. Bubbles are getting larger at 1.50

Stopwatch stopped at 2 min.

Zinc

After 10 seconds there are small bubbles on the edges of the piece of zinc. After 30 seconds the bubbles grow larger and they begin appearing on the face of it.

Stopwatch stopped at 2 min.

After 10 seconds the acid turns a clear light pink color. There is fizzing and bubbles rising from the piece of zinc at 40 sec .Big bubbles appear at the bottom of the container, and rise up at a medium speed. There is smaller bubbles on the surface of the metal piece at 1 min.At 2 min bubbles are still fizzing

Stopwatch stopped at 2 min.

Copper

The metal turns pinkish, when the acid reacts with it. The acid gets a light brown color. There are little brown particles in the edges of the container. After 20 seconds there isn’t much visible change.