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C4 F) The Reactivity Series
C4 F) The Reactivity Series
Metals react by losing electrons and becoming positive ions. Different metals have different reactivities. A more reactive metal will lose electrons easier than a less reactive metal. The reactivity series is shown below.
Hydrogen and carbon are not metals, but they are included in the reactivity series (we will find out why carbon and hydrogen are included when we look at extracting metals from their ores). Out of the elements in the reactivity series, the most reactive metal is potassium and the least reactive metal is copper.
Reacting Metals with Water or Acids
Some metals react with water and acids. We are now going to have a look at the equations for the reactions of metals with water and acids.
Reaction with Water
Some metals react with water to produce a metal hydroxide and hydrogen. The word equation is shown below.
Some metals react with water and acids. We are now going to have a look at the equations for the reactions of metals with water and acids.
Reaction with Water
Some metals react with water to produce a metal hydroxide and hydrogen. The word equation is shown below.
An example is the reaction of sodium and water to produce sodium hydroxide and hydrogen. The word and chemical equations are shown below.
It is only really the more reactive metals that react with water. The less reactive metals do not really react with water.
Reaction with Acids
Most metals react with acids to produce a salt and water (this equation was looked at in more detail in a previous section – click here to be taken to this section). The word equation for the reaction of a metal and an acid is shown below.
Reaction with Acids
Most metals react with acids to produce a salt and water (this equation was looked at in more detail in a previous section – click here to be taken to this section). The word equation for the reaction of a metal and an acid is shown below.
When we react zinc with hydrochloric acid, the products are zinc chloride (the salt) and hydrogen. The word and chemical equations are shown below.
Testing for Hydrogen Gas
During both of the reactions between a metal and water or a metal and an acid, hydrogen gas was produced. We can test for the presence of hydrogen gas by collecting some of the gas in a test tube. We then hold a lit splint above the test tube that we collected the gas in; if we hear a squeaky pop, it tells us that the gas is hydrogen (we could also hold our lit splint above where the hydrogen gas was produced rather than collecting it in a test tube).
During both of the reactions between a metal and water or a metal and an acid, hydrogen gas was produced. We can test for the presence of hydrogen gas by collecting some of the gas in a test tube. We then hold a lit splint above the test tube that we collected the gas in; if we hear a squeaky pop, it tells us that the gas is hydrogen (we could also hold our lit splint above where the hydrogen gas was produced rather than collecting it in a test tube).
Proving the Reactivity Series
We can use the reactions of metals with water or acids to prove the reactivity series. Both of the reactions produce hydrogen gas, which will bubble through the water/ acid. A more reactive metal will react quicker, thus producing hydrogen gas faster, which means that there will be more bubbles bubbling through the water/ acid. So, we can use the number of bubbles produced by the reaction to determine the rate of reaction and the reactivity of the metals.
I am now going to investigate the reactivities of magnesium, iron and copper. I will investigate the reactivities of these metals by reacting the metals with an acid. We place the same mass of each of these metals into a test tube full of a dilute acid, such as dilute hydrochloric acid. We then observe what happens. The setup of the experiment and the outcomes are shown below:
We can use the reactions of metals with water or acids to prove the reactivity series. Both of the reactions produce hydrogen gas, which will bubble through the water/ acid. A more reactive metal will react quicker, thus producing hydrogen gas faster, which means that there will be more bubbles bubbling through the water/ acid. So, we can use the number of bubbles produced by the reaction to determine the rate of reaction and the reactivity of the metals.
I am now going to investigate the reactivities of magnesium, iron and copper. I will investigate the reactivities of these metals by reacting the metals with an acid. We place the same mass of each of these metals into a test tube full of a dilute acid, such as dilute hydrochloric acid. We then observe what happens. The setup of the experiment and the outcomes are shown below:
From the diagram above, we can see that magnesium produced the greatest number of bubbles – this means that out of the 3 metals, magnesium is the most reactive. Copper produced no bubbles, which means that copper didn’t react at all and is the least reactive of the 3 metals. The reaction with iron produced a few bubbles, which means that iron is less reactive than magnesium, but more reactive than copper. So, the order of reactivity for these 3 metals going from most reactive to least reactive is magnesium (most reactive), iron and copper (least reactive).
In this experiment, we used the number of bubbles produced as a proxy for the rate of reaction and reactivity of the metals. This would be fine for the 3 metals that I tested because their reactivities were very different. But if the reactivities of the metals were closer, it may be harder to see which metal was producing more hydrogen gas and therefore which metal is more reactive. We could work out the quantity of hydrogen gas produced more accurately by using a gas syringe – click here to see what the apparatus would look like if we were measuring the volume of gas produced; look at method 2.
When we complete this experiment, there are quite a few variables that we need to keep constant. These variables are:
In this experiment, we used the number of bubbles produced as a proxy for the rate of reaction and reactivity of the metals. This would be fine for the 3 metals that I tested because their reactivities were very different. But if the reactivities of the metals were closer, it may be harder to see which metal was producing more hydrogen gas and therefore which metal is more reactive. We could work out the quantity of hydrogen gas produced more accurately by using a gas syringe – click here to see what the apparatus would look like if we were measuring the volume of gas produced; look at method 2.
When we complete this experiment, there are quite a few variables that we need to keep constant. These variables are:
- The same mass of the metals
- The same surface area/ shape of the metals
- The same concentration of acid
- The same volume of acid
- The same initial temperature of the acid and metal
Measuring Temperature Change
The reaction of a metal with water, and a metal with an acid are exothermic reactions (the reactions give out energy). We can also investigate the reactivity of different metals by measuring the temperature change during the reactions. We will then observe a greater temperature change for a more reactive metal; a more reactive metal will have a greater temperature increase, and a less reactive metal will have a smaller temperature increase.
If we are using temperature change to measure the reactivity of metals, we need to make sure that the mass and surface area of the metals are the same, the concentration and volume of acid are the same, and the starting temperature of the acid and metals are also the same – the only variable that we will change is the type of metal that we are using, and everything else should be the same.
The reaction of a metal with water, and a metal with an acid are exothermic reactions (the reactions give out energy). We can also investigate the reactivity of different metals by measuring the temperature change during the reactions. We will then observe a greater temperature change for a more reactive metal; a more reactive metal will have a greater temperature increase, and a less reactive metal will have a smaller temperature increase.
If we are using temperature change to measure the reactivity of metals, we need to make sure that the mass and surface area of the metals are the same, the concentration and volume of acid are the same, and the starting temperature of the acid and metals are also the same – the only variable that we will change is the type of metal that we are using, and everything else should be the same.