Quantitative chemistry is a very important branch of chemistry because it enables chemists to calculate known quantities of materials. … Quantitative analysis is any method used for determining the amount of a chemical in a sample. The amount is always expressed as a number with appropriate units.
Quantitative Chemistry with Wilson, science made simple through innovative videos and content that aid understanding of this GCSE content.
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Lesson 1 – Relative formula mass, Calculating numbers of atoms and Balancing equations
In this lesson we look at the basics of quantitative chemistry starting with understanding how many atoms make up a compound, then using this to calculate relative formula mass. A simple method of how to balance any equation is also used.
Click on the resources below to accompany the lesson video.
Lesson 2 – Conservation of mass and apparent changes in mass
The Law of the conservation of mass states that no atoms are lost or made during a chemical reaction so that the mass of the products equals the mass of the reactants. This lesson looks at apparent increases and decreases in mass and explains them using the particle model. Resources also focus on chemical measurements, the distribution of results and uncertainty.
Resource 1 & 2 should be used to plot a graph and discuss uncertainy and relate this to apparent changes in mass.
Lesson 3 – Moles HT only
Moles are a measure of chemical amounts. This lesson explains how one mole of a substance is a measure of the number of atoms, molecules or ions of a given substance and is know as Avogadro’s constant with a value of 6.02 x 1023. The mole equation is then used to calculate the mass, or number of moles of an atom or compound.
Lesson 4 – Amounts of substances in equations HT only
It is possible to calculate masses of either the products or the reactants using the mole equation. This lesson focuses on a simple, yet effective way of solving those types of questions. It finishes with an explanation and step by step guide of how to balance equations using the masses of certain substances.
Lesson 5 – Limiting factors HT only
It is common in a chemical reaction to use an excess of one reactant to ensure that all the other reactant is used up. The reactant that is completely used up is called the limiting reactant, this lesson looks at how the limiting reactant can be calculated from given masses of reactants.
Lesson 6 – Concentrations of solutions
Many chemical reactions take place in solutions, this lesson looks at calculating concentrations as a measure of the mass of a solute in a given volume of solvent in grams per dm3, it then moves onto the HT only content of calculating concentrations as a measure of moles per dm3
This lesson does not cover titration calculatiuons, as this is covered in lesson 9.
Lesson 7 – Percentage yield (Chemistry only)
Even though no atoms are gained or lost during a chemical reaction it is not always possible to obtain the calculated amount of a product. This lesson looks at the factors effecting yield and explains how to calculate the percentage yield of a product for it’s actual yield
Lesson 8 – Atom economy (Chemistry only)
In this lesson we look at how atom economy is a measure of the amount of starting materials that end up as useful products and how this can be quantified and then compared.
Lesson 9 – Titration calculations (HT Chemistry only)
Concentrations of unknown substances can be calculated if their volumes are known and the concentration of one of the substances is known. Typically, in schools this is done as a titration where a neutralisation takes place that allows the concentration of either the acid or the alkalis to be calculated.
Lesson 10 – Use of amounts of substances in relation to volumes of gases (HT Chemistry only)
Equal amounts in moles of gases occupy the same volume under the same conditions of temperature and pressure. This lesson explains how to calculate the volume of products and reactants from a balanced equation.