Home
Class 11
CHEMISTRY
State with equations what happens when b...

State with equations what happens when borax is heated on a platinum wire loop and to resulting transparent mass, a mixture amount of `CuO` is added and the mixture is again heated.
(a) First in the oxidising flame and
(b) Then in the reducing flame of a Bunsen burner ?

Text Solution

Verified by Experts

On heating borax on a platinum wire loop, a transparent glassy bead is formed.
`underset("Borax")(Na_(2)B_(4)O_(7)).10H_(2) O overset(Delta)rarr Na_(2)B_(4)O_(7) + 10H_(2)O`
`Na_(2)B_(4) O_(7) overset(Delta)rarr underset(underbrace(underset("metaborate")("Sodium") underset("anhydride")("Boric"))_("Transparent glassy bead"))(2NaBO_(2)+ B_(2) O_(3))`
When this transparent glassy bead is heated with `CuO`,
(a) In oxidising flame, it imparts blue colour to the bead
`CuO + B_(2)O_(3) rarr underset("Cupric metabortae(blue)") (Cu(BO_(2))_(2))`
(b) In reducing flame, the blue cupric metaborate is reducing by `C` present in flame first to form coloured cuprous metaborate and then to metal which products red colour.
`underset(underset(("blue"))("Cupric metaborate"))(2Cu(BO_(2))_(2)) + C rarr underset(underset(("colourless"))("Cuprous metaborate"))(2CuBO_(2) + B_(2)O_(3))+ CO`
`CuBO_(2) + C rarr underset(underset(("red"))("Copper metal"))(Cu + B_(2)O_(3)) + CO`.
Promotional Banner

Topper's Solved these Questions

  • P-BLOCK GROUP 13 - BORON FAMILY

    CENGAGE CHEMISTRY|Exercise Ex 6.1 (Objective)|14 Videos

  • P-BLOCK GROUP 13 - BORON FAMILY

    CENGAGE CHEMISTRY|Exercise Exercise (Linked Comprehension)|37 Videos

  • P-BLOCK GROUP 13 - BORON FAMILY

    CENGAGE CHEMISTRY|Exercise Solved Examples|16 Videos

  • ORGANIC REACTION MECHANISM

    CENGAGE CHEMISTRY|Exercise Analytical and Descriptive|6 Videos

  • P-BLOCK GROUP 14 - CARBON FAMILY

    CENGAGE CHEMISTRY|Exercise Exercises Archives (Subjective)|9 Videos

Similar Questions

Explore conceptually related problems

State with equations what happens when borax is heated on a platinum wire Ioop and to the resulting transparent mass, a minute amount of CuO is added and the mixture is again heated first in the oxidising flame and then in the reducing flame of a Bunsen burner?

What happen when a mixture of cobalt oxide and borax is heated in a flame on a loop of platinum wire?

Borax Bead Test is carried out when the original mixture is coloured. It is done with the help of a cleam platinum wire on which a small loop is made at the end. When borax is heated on platinum wire loop transparent glass like bead is obtained. The hot bead is brought in contact with salt till it reacts with fused borax and colour is imparted to the bead. bead colour is noted. {:("Colour of the bead","Ion"),(1." Blue green",Cu^(2+)),(2." Yellow ",Fe^(3+)),(3." Green",Cr^(3+)),(4." Violet",Mn^(2+)),(5." Dark blue",Co^(2+)),(6." Brown",Ni^(2+)):} Q. The flame used in Borax Bead Test is:

Borax Bead Test is carried out when the original mixture is coloured. It is done with the help of a cleam platinum wire on which a small loop is made at the end. When borax is heated on platinum wire loop transparent glass like bead is obtained. The hot bead is brought in contact with salt till it reacts with fused borax and colour is imparted to the bead. bead colour is noted. {:("Colour of the bead","Ion"),(1." Blue green",Cu^(2+)),(2." Yellow ",Fe^(3+)),(3." Green",Cr^(3+)),(4." Violet",Mn^(2+)),(5." Dark blue",Co^(2+)),(6." Brown",Ni^(2+)):} Q. Glassy bead of :

Borax Bead Test is carried out when the original mixture is coloured. It is done with the help of a cleam platinum wire on which a small loop is made at the end. When borax is heated on platinum wire loop transparent glass like bead is obtained. The hot bead is brought in contact with salt till it reacts with fused borax and colour is imparted to the bead. bead colour is noted. {:("Colour of the bead","Ion"),(1." Blue green",Cu^(2+)),(2." Yellow ",Fe^(3+)),(3." Green",Cr^(3+)),(4." Violet",Mn^(2+)),(5." Dark blue",Co^(2+)),(6." Brown",Ni^(2+)):} Q. Blue bead can be of:

What happens when mixture of NH_(3) and air is passed over heated platinum gauze ?

A chemistry student trying to detect the metallic ion in a salt, makes a paste on a clean platinum wire loop of the salt with concentrated HCl. When he takes a small amount of this paste and keeps it in a non-luminous Bunsen flame, the colour of the flame changes to grassy green.He should, therefore, conclude that the metal is

CENGAGE CHEMISTRY-P-BLOCK GROUP 13 - BORON FAMILY-Ex 6.1 (Subjective)
  1. Why boron does not exist as B^(2+) ion in solution or in compound ?

    Text Solution

    |

  2. The +1 oxidation state is more stable than +3 oxidation state for thal...

    Text Solution

    |

  3. Aluminium chloride exists as dimer. Give reason.

    Text Solution

    |

  4. Why boron halides do not exists as a dimer. While AlCl(3) exists as Al...

    Text Solution

    |

  5. Give reaction for the following : (a) In (III) is more stable than i...

    Text Solution

    |

  6. Why boron and aluminium tend to for, covalent compounds ?

    Text Solution

    |

  7. Molten aluminium bromide is a poor conductor of electricity. Give reas...

    Text Solution

    |

  8. Why B-X bond distance in BX(3) is shorter than theoretically expected ...

    Text Solution

    |

  9. Boric acid can be titrated against sodium hydroxide using phenolphthal...

    Text Solution

    |

  10. Which one is more soluble in diethyl ether : anhydrous AlCl(3) or hydr...

    Text Solution

    |

  11. How is boron obtained from borax ? Give the chemical reactions involve...

    Text Solution

    |

  12. Unlike ordinary fire, thermite reaction cannot be stopped by pouring w...

    Text Solution

    |

  13. (a) Explain why BF(3) exists whereas BH(3) does not. (b) Compare the...

    Text Solution

    |

  14. State with equations what happens when borax is heated on a platinum w...

    Text Solution

    |

  15. What is inorganic benzene ? Why is it so called ? How will you get it ...

    Text Solution

    |

  16. AlF(3) is insoluble in anhydrous HF but dissolves on addition of NaF. ...

    Text Solution

    |

  17. What do you understand by : (a) Ammonal (b) Bentonite ( c) Rubie...

    Text Solution

    |