A student is given four different powdered metals and some dilute sulphuric acid. The student
wants to investigate the reactivity of the four metals
Outline a plan that the student could use to investigate the relative reactivity of the metals. The
plan should use the fact that all four metals react exothermically with dilute sulphuric acid. You
should name the apparatus used and comment on the safe use of the chemicals.
First, set up a polystyrene cup and fill in with a fixed volume such as 25cm3 of Sulphuric acid using a
measuring cylinder. Be careful not to touch sulphuric acid as it may cause corrosion and irritation to
the skin and wear goggles to prevent contaminating the eyes if hands contain chemicals. If touched,
immediately wash thoroughly with water and soap. Next use a thermometer to measure the initial
temperature of the sulphuric acid and record into a table of results. Now add a fixed mass of one
type of powdered metal measured using a mass balance with a spatula and mix the solution with a
glass rod. Quickly place a lid over the cup with a hole fitted in the centre for the thermometer. Wait
for a set time eg 5 min. Then record the final temperature. Repeat the entire experiment using the
remaining three types of powdered metals. Calculate the change in temperature between the initial
and final temperature. The powdered metal with the highest temperature change is the most
reactive metal. Repeat each metal at least three times and calculate a mean temperature changefor
each.
"The more energy levels (shells) of electrons an atom has, the weaker the covalent bonds that it
forms."
Use the above statement to predict and explain how the overall energy change for the reaction of
ethene with chlorine will differ from the overall energy change for the reaction of ethene with
bromine.
The reaction between ethene and chlorine will require more energy to break the strong covalent
bonds than a reaction between ethene and bromine. This is because chlorine has less electron shells
which means that the force between the outer electrons of chlorine and the positive nucleus is
stronger as the distance between the outer electrons and the nucleus is shorter. Therefore, more
energy will be needed to overcome these strong covalent bonds and taken from the surroundings.
However, as the distance between the outer electrons and the positive nucleus is further in a
bromine atom, this means that the force between the outer electron and the positive nucleus is
weak. Therefore, less energy will be needed to overcome these forces and be taken in from the
surroundings.
If Cl-Cl bond changes more, the reaction is more exothermic
If C-Cl bond changes more, the reaction is more endothermic
Electrolysis of acidified water can produce hydrogen and oxygen.
The apparatus for the electrolysis is:
- water containing some dilute sulphuric acid
- two graphite rods
- a suitable container for the electrolysis reaction
wants to investigate the reactivity of the four metals
Outline a plan that the student could use to investigate the relative reactivity of the metals. The
plan should use the fact that all four metals react exothermically with dilute sulphuric acid. You
should name the apparatus used and comment on the safe use of the chemicals.
First, set up a polystyrene cup and fill in with a fixed volume such as 25cm3 of Sulphuric acid using a
measuring cylinder. Be careful not to touch sulphuric acid as it may cause corrosion and irritation to
the skin and wear goggles to prevent contaminating the eyes if hands contain chemicals. If touched,
immediately wash thoroughly with water and soap. Next use a thermometer to measure the initial
temperature of the sulphuric acid and record into a table of results. Now add a fixed mass of one
type of powdered metal measured using a mass balance with a spatula and mix the solution with a
glass rod. Quickly place a lid over the cup with a hole fitted in the centre for the thermometer. Wait
for a set time eg 5 min. Then record the final temperature. Repeat the entire experiment using the
remaining three types of powdered metals. Calculate the change in temperature between the initial
and final temperature. The powdered metal with the highest temperature change is the most
reactive metal. Repeat each metal at least three times and calculate a mean temperature changefor
each.
"The more energy levels (shells) of electrons an atom has, the weaker the covalent bonds that it
forms."
Use the above statement to predict and explain how the overall energy change for the reaction of
ethene with chlorine will differ from the overall energy change for the reaction of ethene with
bromine.
The reaction between ethene and chlorine will require more energy to break the strong covalent
bonds than a reaction between ethene and bromine. This is because chlorine has less electron shells
which means that the force between the outer electrons of chlorine and the positive nucleus is
stronger as the distance between the outer electrons and the nucleus is shorter. Therefore, more
energy will be needed to overcome these strong covalent bonds and taken from the surroundings.
However, as the distance between the outer electrons and the positive nucleus is further in a
bromine atom, this means that the force between the outer electron and the positive nucleus is
weak. Therefore, less energy will be needed to overcome these forces and be taken in from the
surroundings.
If Cl-Cl bond changes more, the reaction is more exothermic
If C-Cl bond changes more, the reaction is more endothermic
Electrolysis of acidified water can produce hydrogen and oxygen.
The apparatus for the electrolysis is:
- water containing some dilute sulphuric acid
- two graphite rods
- a suitable container for the electrolysis reaction
