Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
What would happen with non-electrolytes?
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →Water is often used as the solvent in electrolysis experiments. Pure water conducts electricity only very weakly, but when a small amount of sodium chloride is added, it conducts electricity much better.
Explain why pure water is a poor conductor of electricity and why adding sodium chloride increases the conductivity so much.
Question 12
4 marks · Normal
Answer and see the solution →The table below shows results from an experiment where a student measured the volume of oxygen gas produces at the anode when different substances are electrolysed:
Results of electrolysis Substance (aq) Bulb lights? Volume of O2 at anode (cm³) Sodium sulfate Yes 18.5 Copper(II) sulfate Yes 17.8 Sugar No 0 Ethanol No 0 (a)[2 marks]Identify which substances are electrolytes and which are non-electrolytes. Explain your choices.
(b)[2 marks]State what this experiment shows about the type of bonding in sugar and ethanol.
Question 13
1 mark · Normal
Answer and check →The student sets up an apparatus to test substance X for electrical conductivity. The bulb stays off, and even after substance X is dissolved in water, there is still no current. What does this suggest about substance X?
- A.It is an ionic compound that conducts electricity when solid.
- B.It is a covalent compound that forms ions in water.
- C.It is a non-electrolyte and does not produce ions in solution.
- D.It is an acid and must form ions in solution.
Question 14
2 marks · Normal
Answer and see the solution →Explain why potassium iodide (KI) will conduct electricity when molten but not as a solid.
Question 15
4 marks · Normal
Answer and see the solution →You are given a white solid (substance Y) that is soluble in water. You need to determine whether it is an ionic compound, a covalent compound, or a non-electrolyte.
(a)[2 marks]Describe an experiment you could do to determine the type of substance.
(b)[2 marks]State what you would observe if substance Y is an ionic compound and explain your answer.
Question 16
3 marks · Normal
Answer and see the solution →A student wants to find out whether substance X is an ionic compound, a covalent compound (non-electrolyte), or an acid using an experiment. She sets up the following experiment in which two carbon electrodes are placed in a solution of substance X, connected to a power supply and a bulb, as shown in the diagram:
Apparatus for testing conductivity. In three separate experiments she uses:
Test Substance in solution Observation A X dissolved in water Bulb does not light up B Molten X Bulb lights up C Aqueous acid Bulb lights up Using the data above, calculate whether substance X is ionic, covalent (non-electrolyte), or an acid. Explain your reasoning.
Question 17
2 marks · Hard
Answer and see the solution →A student tries to electrolyse solid iodine and observes no current flows through the circuit. The student then dissolves the iodine in water and tries again, but the bulb still does not light. State and explain what these results show about the electrical properties and bonding type of iodine.
Question 18
5 marks · Hard
Answer and see the solution →A student investigates the electrical conductivity of three white solids: compound A, compound B and compound C. The student tests each substance (i) as a solid, (ii) after dissolving it in water, and (iii) after melting it. The observations are recorded below:
Conductivity results for three compounds Substance Solid Aqueous solution Molten Compound A Does not conduct Does not conduct Does not conduct Compound B Does not conduct Conducts Conducts Compound C Does not conduct Does not conduct Conducts (a)[4 marks]For each compound (A, B and C), state whether it is ionic, covalent (non-electrolyte), or another type. Give a reason for each answer.
(b)[1 mark]Suggest a familiar example of a substance that would behave in the same way as compound A.
Question 19
2 marks · Hard
Answer and see the solution →A student is investigating whether a white crystalline solid is an ionic compound or a covalent compound. The student finds that the solid does not conduct electricity, and that dissolving the solid in water still does not allow the solution to conduct electricity. State what type of compound the solid is and explain your reasoning.