●Structure●+●Properties●
Formula: Na2B4O7 · 10H2O
| Element | Number in one molecule | Molar mass in one molecule | Percent composition by number | Percent composition by mass |
| Sodium | 2 | 46.0 | 4.7% | 12.1% |
| Boron | 4 | 43.2 | 9.3% | 11.3% |
| Hydrogen | 20 | 20 | 46.5% | 5.2% |
| Oxygen | 17 | 272 | 39.5% | 71.4% |
Sodium Tetraborate is held together by ionic
and covalent bonds. The Na2
is connected to the
B4O7
by ionic bonds, and the
B4O7
is held together by covalent bonds.
Borax is used in a process called a “bead test,” which replaces or verifies the flame test** to identify certain metals. A platinum wire is formed into a small loop and cleaned. The loop is dipped into a sample of dry, powdered borax and then put into a Bunsen burner flame until it melts. A tiny amount of the unknown metal compound is added to the melted borax bead, and then heated. The bead will change colors to satisfy which metal was present.
**Note: The flame test
is where metal solutions are put in Bunsen burner flames. The color of the
flame changes based on what metal is introduced, with each metal having a
specific color. This process determines the unknown metal.
Borax is not very reactive. It is used in cleaning products, therefore it must be pretty mild. It is used in Flux for elding and soldering so that oxide is not produced. This means that Borax resists combining with oxygen as well. It is used in the “bead test” because it does not interfere with the testing of the metals.
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