Year 10 - Science
Empirical formula calculations: using moles
Calculations involving masses
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers writing chemical formulae, balancing equations, and using the conservation of mass. It includes calculating moles, empirical formulae, relative formula masses, and theoretical yields. Emphasis is on stoichiometry, concentration, gas volumes, and using standard form.
Lesson Summary
You will learn to determine the empirical formulae of simple compounds using reactant masses or percentage composition.
Key Notes
- Empirical formula is the simplest whole number ratio of atoms of each element in a compound.
- Using the masses of elements reacted together, or their percentage compositions, calculate the empirical formula.
- Knowing the relative formula mass of a substance, and its empirical formula, calculate the molecular formula.
- Know that we are using moles, and molar ratios to calculate formulae
Vocabulary To Learn
- empirical formula: A substance's empirical formula shows the simplest whole number ratio of atoms of each element in a compound.
- relative formula mass: The relative formula mass of a substance is the sum of the relative atomic masses of all the atoms in a formula.
- molecular formula: A substance's molecular formula shows the actual number of atoms of each element in a molecule of a compound.
- mole: A mole of something is 6.02 × 10²³ of it. The mass of a mole of a substance is its relative mass expressed in grams.
Common Mistakes To Avoid
- Pupils easily confuse empirical and molecular formula.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Empirical formula is the simplest whole number ratio of atoms of each element in a compound. Using the masses of elements reacted together, or their percentage compositions, calculate the empirical formula.
2. Define this scientific word and use it in context. 'empirical formula'
A substance's empirical formula shows the simplest whole number ratio of atoms of each element in a compound. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils easily confuse empirical and molecular formula. Correction: Provide multiple examples of formula and challenge pupils to distinguish them as molecular or empirical formula; if the former, push pupils to suggest the molecule's empirical formula.
More Lessons In This Unit
- Balancing equations Study Guide
- Conservation of mass Study Guide
- Converting between mass and volume using moles Study Guide
- Converting between mass and volume using moles (RAM 1 d.p.) Study Guide
- Deducing an empirical formula experimentally Study Guide
- Deducing an empirical formula experimentally: using moles Study Guide
- Determining an equation experimentally: magnesium oxide Study Guide
- Determining an equation experimentally: magnesium oxide (RAM 1 d.p.) Study Guide
- Determining an equation experimentally: sodium hydrogencarbonate Study Guide
- Determining an equation experimentally: sodium hydrogencarbonate (RAM 1 d.p.) Study Guide
- Determining an equation from given values Study Guide
- Determining an equation from given values (RAM 1 d.p.) Study Guide
- Empirical formula calculations Study Guide
- Gas volumes Study Guide
- Gas volumes (RAM 1 d.p.) Study Guide
- Limiting reactants Study Guide
- Limiting reactants (RAM 1 d.p.) Study Guide
- Mass in a chemical reaction Study Guide
- Mass in a chemical reaction (RAM 1 d.p.) Study Guide
- Mass in a chemical reaction: using moles Study Guide
- Mass in a chemical reaction: using moles (RAM 1 d.p.) Study Guide
- Moles and masses Study Guide
- Moles and masses (RAM 1 d.p.) Study Guide
- Representations of a mole Study Guide
- Representations of a mole (RAM 1 d.p.) Study Guide
- The mole Study Guide
- The mole (RAM 1 d.p.) Study Guide
- Three types of chemical reaction Study Guide
- Uncertainties in measurements: chemistry Study Guide
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