Investigating the energy change in reactions involving metals

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Investigating the energy change in reactions involving metals


To find the energy change as we react several group one elements with hydrochloric acid.


The reactivity of a metal is directly proportional to its position on the periodic table of elements, and is determined by the number of protons and the number of electron shells the atom has. It is said that metals become stronger and more reactive as you move left, because there are less electrons which need to be lost. Metals are also more reactive as you move down the table because the atomic radius becomes larger to an extra filled electron shell, making the outer electrons further away from the nucleus. Electrons are held in their shells by a force from the protons in the nucleus, and the further away the outer electrons are from the nucleus, the less of a pull the nucleus will be able to exert in order to hold the outer electron.

Because I have chosen to find the energy change in group one elements, I predict that all three metals, Lithium, Sodium and Potassium, will react violently with hydrochloric acid. More specifically, I hypothesize that Lithium, atomic number 3, will be the least reactive, and thus will produce the least amount of energy. This is because, as you can see on the diagram at the top right, the outer electron is closer to the nucleus than the other two metals, and so the force holding it is quite large. Sodium, atomic number 11, will be the second most reactive, as its atoms are larger. And finally, Potassium, atomic number 19, will be the most reactive and produce the most energy because its outer electrons are least strongly held by the positive nucleus.


Independent – Group one metal (lithium, sodium and potassium).  

Dependent – Energy produced by element (change in temperature)

Controlled – amount of metal used (0.03g), amount of hydrochloric acid (50ml), concentration of acid (0.1mol), and the apparatus used (thermometer, measuring cylinder, beaker, electric balance, ceramic tile, forceps, scalpel, and litmus paper – which are all cleaned between each change of metal or trial).


Below is a diagram showing the setup of our experiment:


  1. First, put on your safety goggles.
  2. Pour 50ml of hydrochloric acid into a measuring cylinder, and then into a clean beaker.
  3. With a thermometer, measure the temperature of the acid, and record it in your book.
  4. At the side, turn on the electric balance, and place a piece of litmus paper on top. Once the balance has recorded the weight of the paper, click the tare button so the weight is now 0g.
  5. With a pair of forceps, pick up a piece of lithium from the bottle and place it on the litmus paper on top of the ceramic tile. Remember to quickly close the bottle with lithium.
  6. Estimating how much will equal to 0.03g, cut a little part of lithium from the piece taken with a scalpel. Pick up the small piece of lithium and place it on the litmus paper already on the electric balance. If the balance reads 0.03g, quickly take the paper with the lithium to the beaker with hydrochloric acid. If not, then move the piece of lithium back to the ceramic tile, and continue estimating until it reads 0.03g.
  7. Place the lithium into the hydrochloric acid (as shown in the diagram), and as you watch the reaction take place, record the qualitative data in your book.
  8. As soon as the reaction stops, measure the temperature with the thermometer, and record it in a table of results, so we can find out the temperature change for Lithium.
  9. After recording, dispose of the solution in the beaker in the waste department, not the sink.
  10. Repeat steps 2 to 9 using the other metals instead of Lithium. Remember to wait until the beaker has cooled down from the reaction before picking it up. Clean the thermometer with a wet tissue, and clean the measuring cylinder, beaker, scalpel and forceps.
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Results & Observations

Raw Data » Table of results showing the initial and final temperatures of reactions between several group one metals with hydrochloric acid

Lithium -

Average initial temperature: 21.4 + 21.4 + 22.0 = 21.6


Average final temperature: 24.6 + 26.9 + 25.1 = 25.5


Average change in temperature: 25.5 – 21.6 = 3.9

Sodium -

Average initial temperature: 21.4 + 21.6 + 22.0 = 21.7


Average final temperature: 22.2 + 23.3 + 22.6 = ...

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