Table of Contents
A Brief Introduction to Salt Analysis
Salt analysis is a technique used to measure the concentration of salt in a sample. This can be used to determine the purity of a sample, or to measure the amount of salt present in a solution. The technique involves using a spectrometer to measure the absorbance of light at a specific wavelength. This can be used to calculate the concentration of salt in the sample.
A Walkthrough for Analysing Salts
- When analysing salts, it is important to first identify the cation and anion. The cation is the positively charged ion and the anion is the negatively charged ion.
- Once the cation and anion have been identified, the next step is to determine the formula for the salt. The formula for a salt is the sum of the cation and anion formulas.
- For example, if the cation is sodium (Na+) and the anion is chloride (Cl-), the formula for the salt is NaCl.
Shortcuts to Identify Ions
The following are a few shortcuts to help identify ions:
- Cations are always positive, while anions are always negative.
- Metals always form cations, while non-metals always form anions.
- The charge on an ion is always the sum of the charges on its constituent atoms.
- Ions always have the same number of protons as electrons.
A Guide to Common Cations to Help with Salt Analysis
The following guide provides information on common cations that can used to help with salt analysis.
A Guide to Common Anions in Salt Analysis
Anion Name Formula Molecular Weight Chloride Cl- 35.45 Sulphate SO4-2 96.07 Carbonate CO3-2 54.01 Nitrate NO3- 62.00 Phosphate PO4-3 98.00
Anion Name Formula Molecular Weight Bromide Br- 79.92 Iodide I- 126.90
Preliminary Tests (Anions & Acid Radicals)
In this experiment, you will be testing for the presence of anions and acid radicals.
Materials
- Sodium carbonate solution
- Phenolphthalein indicator
- Assorted acids (vinegar, lemon juice, etc.)
Procedure
- To test for anions, place a few drops of sodium carbonate solution on a watch glass.
- Add a few drops of an acid to the watch glass.
- Observe the color of the solution.
If the solution turns pink, then there are anions present.
- To test for acid radicals, place a few drops of sodium carbonate solution on a watch glass.
- Add a few drops of an acid to the watch glass.
- Observe the color of the solution.
If the solution turns colorless, then there are acid radicals present.
