Home > Subjects > Chemistry > Level 2 > 2.3 Quantitative chemical problems > Achievement criteria
- Subject: Chemistry
- AS: AS90763
- Level: 2
- Credits: 2
- Internal
Chemistry 2.3 Solve simple quantitative chemical problems
Achievement criteria
The criteria for each level of achievement is based on your ability to solve problems involving varying number of steps.
Achievement
- Solve simple quantitative problems.
- A simple quantitative problem may involve:
- using the relationships n=m/M, c=n/V to calculate one variable given the other two (the relationships are not given)
- determining molar masses from given atomic masses and formulae.
Achievement with Merit
- Solve quantitative problems.
- A quantitative problem will involve at least two steps and requires an application of the relationships n=m/M, c=n/V. Some examples of suitable problems include:
- calculating the percentage composition of a compound
- determining empirical and molecular formulae
- calculations involving determination of the mass of solid needed to prepare a given volume of a standard solution
- determining, in moles, the amount of water removed on heating a sample of a hydrated salt to constant mass.
Achievement with Excellence
- Solve complex quantitative problems.
- Complex problems will involve more than two steps and the use of stoichiometric principles. Examples could include:
- calculating the mass of a substance produced or consumed in a reaction given the mass of another reactant or product and the balanced equation
- determining the number of waters of crystallisation in the formula of a hydrated salt
- determining the concentration of a solution given titration data and the balanced equation.
- Answers to your calculations will demonstrate correct units and appropriate use of significant figures.
