Empirical formulae and Molecular formulae – Tyler de Witt video

In this video, the lovely Tyler de Witt explains Empirical Formulae and Molecular formulae.

(Please excuse the horrid error right at the start where the video shows a diagram of prop-2-ene, but it is labelled ‘ethene’ by mistake.)

This second video then explains how, if given an empirical formula and a molecular mass, you can calculate the molecular formula:

Concentration (molarity) practice problems – Tyler de Witt video

Here is a video to help you with concentration calculations. In Chemistry, concentration is know as molarity (i.e. the amount per volume).

Note that in the video, the lovely Tyler de Witt uses the unit “liter” for volume, but the correct international unit (as used by UK exam boards) is decimeters cubed (dm3) which is the same thing as Tyler’s “liter”.

and a follow up video with some more examples:

2019-02-10T14:51:45+00:00Categories: Uncategorized|Tags: , , , |

In an ion, the number of protons does not equal the number of electrons – Tyler de Witt video

In an electrically neutral ATOM, the number of electrons equals the number of protons.

However, an ION is an atom (or group of atoms) which has either gained or lost some electrons, so for an ION the number of electrons does not equal the number of protons.

This excellent Tyler de Witt video explains this clearly:

2019-02-10T14:04:01+00:00Categories: Uncategorized|Tags: , , , |
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Section 1: Principles of chemistry

      a) States of matter

      b) Atoms

      c) Atomic structure

     d) Relative formula masses and molar volumes of gases

     e) Chemical formulae and chemical equations

     f) Ionic compounds

     g) Covalent substances

     h) Metallic crystals

     i) Electrolysis

 Section 2: Chemistry of the elements

     a) The Periodic Table

     b) Group 1 elements: lithium, sodium and potassium

     c) Group 7 elements: chlorine, bromine and iodine

     d) Oxygen and oxides

     e) Hydrogen and water

     f) Reactivity series

     g) Tests for ions and gases

Section 3: Organic chemistry

     a) Introduction

     b) Alkanes

     c) Alkenes

     d) Ethanol

Section 4: Physical chemistry

     a) Acids, alkalis and salts

     b) Energetics

     c) Rates of reaction

     d) Equilibria

Section 5: Chemistry in industry

     a) Extraction and uses of metals

     b) Crude oil

     c) Synthetic polymers

     d) The industrial manufacture of chemicals

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