B.2 Algebra

Understand and use =, <, ≪, ≫, >, ∝, ~ and the equilibrium sign.

Use b.2.1—mathematical symbols to connect the rule to the data and decision in the question.

This matters because b.2.1—mathematical symbols determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.1—mathematical symbols to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.2.1—Mathematical symbols is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

Change the subject of an equation in structured and unstructured chemical calculations. A2 applications include calculating a rate constant from a rate equation.

Use b.2.2—changing the subject of an equation to connect the rule to the data and decision in the question.

This matters because b.2.2—changing the subject of an equation determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.2—changing the subject of an equation to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Substitute numerical values into algebraic equations using appropriate physical units, including mole calculations. A2 applications include rate and equilibrium-constant calculations.

Use b.2.3—substitution into algebraic equations to connect the rule to the data and decision in the question.

This matters because b.2.3—substitution into algebraic equations determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.3—substitution into algebraic equations to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Solve algebraic equations, including Hess's law calculations. A2 applications include calculating a rate constant from a rate equation.

Use b.2.4—solving algebraic equations to connect the rule to the data and decision in the question.

This matters because b.2.4—solving algebraic equations determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.4—solving algebraic equations to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: use the formula and units given in the question, show the substitution and interpret the result; the calculation alone is not the conclusion.

Use logarithms for quantities spanning several orders of magnitude, including pH and pKa calculations.

Use b.2.5—logarithmic quantities to connect the rule to the data and decision in the question.

This matters because b.2.5—logarithmic quantities determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.5—logarithmic quantities to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.2.5—Logarithmic quantities is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.