B.3 Graphs

Translate information between graphical, numerical and algebraic forms, including interpreting spectra. A2 applications include determining reaction order and deriving rate expressions from graphs.

Use b.3.1—translating between data forms to connect the rule to the data and decision in the question.

This matters because b.3.1—translating between data forms determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.1—translating between data forms to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.1—Translating between data forms is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Plot two variables from experimental or other data, including concentration–time graphs with an appropriate best-fit curve.

Use b.3.2—plotting two variables to connect the rule to the data and decision in the question.

This matters because b.3.2—plotting two variables determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.2—plotting two variables to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.2—Plotting two variables is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Determine the slope and intercept of a linear graph, including finding a zero-order rate constant from the gradient of a concentration–time graph.

Use b.3.3—slope and intercept of a linear graph to connect the rule to the data and decision in the question.

This matters because b.3.3—slope and intercept of a linear graph determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.3—slope and intercept of a linear graph to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.3—Slope and intercept of a linear graph is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Calculate rate of change from a graph showing a linear relationship, including finding a zero-order rate constant from a concentration–time gradient.

Use b.3.4—rate from a linear graph to connect the rule to the data and decision in the question.

This matters because b.3.4—rate from a linear graph determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.4—rate from a linear graph to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.4—Rate from a linear graph is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Draw and use the slope of a tangent to a curve as a measure of rate of change, including determining reaction order by the initial-rates method.

Use b.3.5—tangents and instantaneous rates to connect the rule to the data and decision in the question.

This matters because b.3.5—tangents and instantaneous rates determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.3.5—tangents and instantaneous rates to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.3.5—Tangents and instantaneous rates is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.