Science is for Kids

This video summarizes an experiment performed to experimentally determine the formula ulnits of magnesium chloride. In the lab the mass of a small sample of magnesium ribbon is measured. The metal is then placed into a beaker and concentrated HCl is added. When the reaction is complete the beaker is heated to drive off water and any unreacted HCl. Safety Note: This should be done in a fume hood to avoid breathing in any HCl fumes! After all the liquid has been removed from the beaker a precipitate of magnesium chloride is left behind. The mass of this compound is measured and compared to the original amount of magnesium to determine the added mass of chlorine. The data collected allows students to calculate the formula units of the magnesium chloride salt. The reaction is summarized by the following chemical equation. 2Mg  +  HCl  → MgCl 2 + H 2 The compound forms with a 1:2 ratio of magnesium to chlorine. This is because magnesium has two valen...

An interesting challenge in science is measuring things that can't be measured directly. Direct measurements are pretty straight forward.  If you want to know the mass of a pencil, you simply use a balance to measure the pencil's mass.  Sometime there are things that we want to measure which can't be measured directly.  Luckily we can use indirect measurements.  This is when we measure one thing to determine a different measurement. This video shows an experiment using a spectrophotometer to measure the amount of light which is absorbed by a solution of iron (III) chloride.  The data can be used to create a standard curve which will be used to calculate the concentration of the solution of iron(III) chloride.  The concentration of the iron (III) chloride can't be measured directly by the spectrophotometer, but it can be determined as an indirect measurement by analyzing the absorption data. I hope this was helpful!

The stock naming system uses roman numerals to indicate the oxidation state of metal ions in ionic compounds.  It is used because many metals have more than one possible oxidation state (charge).  One example of this is tin.  The two most common oxidation states of tin are 2+ and 4+; a Roman numeral is used in the name of the compound to tell us which oxidation state is present in a given compound of tin. In the past it was also common to see names of compounds using their Latin names.  Some examples include ferrum for iron and aurum for gold.  In the Latin naming system, different suffixes are used to indicate the oxidation state of the metal ion. I hope this is helpful!