Exam Questions Flashcards
Which group of elements had not been discovered when Mendeleev Periodic table was published?
Group 0 / Noble gases
What is an isotope?
atoms with the same number of protons but with different number of neutrons.
Acids react to produce salts.
Universal indicator is added to water and then nitric acid is added to the mixture.
Give the colour change when nitric acid is added to the mixture of
universal indicator and water
Green to Red
What happens to the pH of water when nitric acid is added?
Decreases
What is the state symbol for nitric acid?
aq
The formula of the zinc ion is Zn2+
The formula of the nitrate ion is NO3-
What is the chemical formula for zinc nitrate?
Zn(NO3)2
Acids react with insoluble metal oxides to produce salts.
Plan a method to produce a pure, dry sample of the soluble salt copper chloride from an acid and a metal oxide.
[6 marks]
1.react hydrochloric acid with copper oxide.
2.in a suitable container.
3.warm (hydrochloric) acid
4.add copper oxide until solid remains
5.stir
6.filter excess copper oxide
7.pour solution into a evaporating basin
8.use a water bath or electric heater
9.heat to partially evaporated
10.leave to cool / evaporate.
Carbon can exist in a number of different structures.
The first fullerene to be discovered was Buckminsterfullerene.
What is the formula of Buckminsterfullerene?
C60
Graphite is a form of carbon.
Explain why graphite conducts electricity.
Graphite has delocalised electrons.
so the delocalised electrons carry electrical charge through the structure.
Steel is an alloy of iron and carbon.
Explain why steel is harder than iron (3 marks)
Carbon atoms have different sizes to iron atoms.
So carbon atoms distort the layers of iron atoms.
therefore layers cannot slide.
Hydrogen gas and oxygen gas are produced when sodium sulfate solution is electrolysed.
Explain how oxygen gas is produced in the electrolysis of sodium sulfate solution (4 marks)
Water molecules break down to produce OH- ions.
Which are attracted to the positive electrode.
Where OH- ions lose electrons / oxidised.
Methane, ethane, propane and butane all react with oxygen to produce carbon dioxide and water.
Suggest why a mixture of methane and oxygen does not react at room temperature.
Answer in terms of particles.
[2 marks]
Particles collide
but at room temperature particles dont have enough energy
Aluminium is produced by the reduction of aluminium oxide (Al2O3).
What is meant by the term reduction?
loss of oxygen
Or
Al3+ gains electrons
Oxygen is formed at the positive carbon electrodes.
Explain why the positive carbon electrodes must be continually replaced
[3 marks]
At high temperature.
oxygen reacts with carbon / electrode.
electrode burns / wears away.
to produce carbon dioxide.
Suggest one limitation of using a ball and stick model for a water molecule.
[1 mark]
Any one from:
Not to scale
Not 3D
incorrect arrangement in space
electrons not shown
Ice has a low melting point.
Water molecules in ice are held together by intermolecular forces.
Complete the sentence.
Ice has a low melting point because the
intermolecular forces are ___________________.
Weak
What is the number of bonds formed by each carbon atom in diamond?
4
Give two physical properties of diamond.
[2 marks]
Very hard
Very high melting point
Does not conduct electricity
Name two other substances with giant covalent structures.
[2 marks]
Graphite
Silicon dioxide
A student investigated the temperature change when magnesium was added to copper sulfate solution.
This is the method used.
- Pour 30 cm3 of copper sulfate solution into a polystyrene cup.
- Measure the temperature of copper sulfate solution every minute for 3 minutes.
- Add magnesium on the fourth minute.
- Measure the temperature of the mixture at 5 minutes and then every minute up to 14 minutes.
What is the dependent variable in this investigation?
[1 mark]
Temperature change
Suggest why the copper sulfate solution was left for four minutes before adding the magnesium.
[1 mark]
to reach a constant temperature
This question is about elements.
Caesium is in Group 1 of the periodic table.
Explain what happens to caesium atoms and to oxygen atoms when caesium reacts with oxygen to produce caesium oxide.
You should answer in terms of electrons.
[4 marks]
Caesium atom loses one electron
and oxygen atoms gain two electrons
so two caesium atoms react with one oxygen atom
to form ions with full outer shells
Explain why caesium is more reactive than sodium.
You should answer in terms of electrons.
[4 marks]
Caesium has more shells
so the outer shell is further away from nucleus
so weaker attraction between nucleus and outer shell
so outer electron is more easily lost
This question is about salts. box
Ammonium nitrate solution is produced when ammonia gas reacts with nitric acid.
Give the state symbol for ammonium nitrate solution.
aq
What is the formula of nitric acid?
HNO3
Ammonia gas dissolves in water to produce ammonia solution.
Ammonia solution contains hydroxide ions, OH–
A student adds universal indicator to solutions of nitric acid and ammonia.
What colour is observed in each solution?
[2 marks]
Colour in nitric acid:
Colour in ammonia solution:
Colour in nitric acid: Red
Colour of ammonia solution: Purple / Blue
This question is about elements in the periodic table.
What order did scientists use to arrange elements in early periodic tables?
Atomic weight.
In the early periodic tables some elements were placed in the wrong groups.
Mendeleev overcame this in his periodic table.
Give one way Mendeleev did this
Left gaps in the periodic table.
This question is about electrolysis.
Some metals are extracted from molten compounds using electrolysis.
Why is electrolysis used to extract some metals?
Metal is too reactive to be extracted using carbon.
Aluminium is produced by electrolysis of a molten mixture.
What two substances does the molten mixture contain?
Aluminium oxide and Cyrolite
Explain why sodium is less reactive than potassium.
[4 marks]
Sodium has fewer shells
Outer electron is closer to the nucleus
meaning there is a greater attraction between the nucleus and outer shell
so electron is less easily lost.
Nickel is extracted from nickel oxide from the reduction of oxygen using carbon.
How is carbon used to extract nickel from nickel oxide.
Nickel is less reactive then carbon so carbon displaces the nickel and removes the oxygen from the oxide leaving the nickel.
What are the two differences between the properties of iron and sodium?
sodium is a non-transition metal with low melting and boiling points and is a soft metal.
Whereas iron is a transition metal with very high melting and boiling points and is a hard metal.
