The method and the results are on the ionic bonding lab. Do the analysis yourself first, then check the answers below.
Quick answer: Ionic bonding is the strong electrostatic attraction between oppositely charged ions, formed when metal atoms transfer electrons to non-metal atoms. These answers go with the Chemistry 9-10 lab on ionic bonding: the graph, the calculations, the uncertainties and the conclusion explained, for all 7 analysis questions.
These model answers use the sample readings. They connect the size of the current to the number of mobile ions and explain why solids and sugar solution do not conduct.
Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: HS-PS1-3, GCSE C2
Question 1 Plot the graph
The points rise steadily, almost in a straight line through the origin: 0.3, 38, 72, 105, 138, 168 mA. The slope is nearly constant, with a very slight levelling off at higher masses.The current increases almost in proportion to the mass dissolved.
Question 2 Explain the trend
Dissolving more salt releases more Na⁺ and Cl⁻ ions. More mobile charged particles carry more charge each second, so the current increases.More ions free to move means a larger current.
Question 3 Gradient
Increase = 168 − 0.3 = 167.7 mA over 5.0 g. Gradient = 167.7 ÷ 5.0 = 33.5 mA/g.About 34 mA per gram.
Question 4 Solids and sugar
In the solid the ions are fixed in the lattice. In solution they are free to move. Sugar dissolves as separate molecules and does not form ions, so no charge carriers exist.Ionic solid: ions fixed. Sugar: no ions.
Question 5 Interpolate
Halfway between 105 mA (3.0 g) and 138 mA (4.0 g) gives (105 + 138) ÷ 2 = 121.5 mA.About 122 mA.
Question 6 Control variables
Electrode separation, electrode depth and volume of water (or temperature). Each changes the resistance of the solution, so a change would alter the current even if the amount of salt were the same.Separation, depth and volume (or temperature) are kept fixed.
Question 7 Evaluate
If the resolution is ±1 mA, the percentage uncertainty = 1 ÷ 38 × 100 = 2.6 %. Improvement: use a more sensitive ammeter, repeat the measurement and take a mean.2.6 %; use repeats and a more sensitive meter.
