Why do silver articles turn black when kept in the open for a few days?

Monjur Alahi

A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
(a) Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
(b) Name the black substance formed and give its chemical formula.


0 like 0 dislike
2 views
Share with your friends

1 Answers

Salim Ahmed Kawsar

Call

(a) Metals such as silver when attacked by substances around it such as moisture, acids, gases etc, are said to corrode and this phenomenon is called corrosion.
(b) The black substance is formed because silver (Ag) reacts with H2S present in air. It forms thin black coating of silver sulphide (Ag2S).

0 like 0 dislike
1 views
Talk Doctor Online in Bissoy App
In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal.

Answer 2AgNO3 (aq) + Cu (s) → Cu(NO3)2 (aq) + 2Ag (s) Silver Nitrate + Copper → Copper Nitrate + Silver

1 Answers 1 views
A copper coin was kept dipped in silver nitrate solution for a few hours/days.

Copper is more reactive than silver. Hence, it displaces silver from the silver nitrate solution according to the given reaction. Cu(s) +   2AgNO3(aq) --------> Cu(NO3)2(aq)   +    2Ag(s) Copper       Silver nitrate ...

1 Answers 1 views
A copper coin was kept dipped in silver nitrate solution for a few hours/days

Copper is more reactive than silver. Hence, it displaces silver from the silver nitrate solution according to the given reaction.  Cu(s) +   2AgNO3(aq) --------> Cu(NO3)2(aq)   +    2Ag(s)  Copper       Silver nitrate ...

1 Answers 1 views
Samuel had a silver coin which turned black. He kept the coin in a

The blackness of silver coin is due to the formation of silver sulphide on its surface due to its exposure to air. On boiling, the aluminium foil reacts with the...

1 Answers 4 views
Wheat dough if left in the open, after a few days, starts to emit a foul smell and becomes unfit for use. Give reason.

Carbohydrates in wheat dough encourage growth of yeast and other saprophytic fungi which break down carbohydrates, and emit a foul smell.

1 Answers 1 views
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.

(a) Yes, rust is quite different from iron. (b) No. (c) Yes, it is a chemical change. (d) (i) Setting of curd from milk. (ii) Burning of magnesium ribbon to form magnesium oxide.

1 Answers 1 views
Match the articles given in Column I with the articles of Column II

(a) – (ii), (b) – (iii), (c) – (i), (d) – (iv)

1 Answers 1 views
Will a leaf taken from a potted plant kept in a dark room for a few days turn blue black when tested for starch? Give reasons for your answer

No, all the starch stored in the leaf would have been used up by the plant. No starch would be synthesised afresh due to non-availability of sunlight.

1 Answers 1 views
A silver article generally turns black when kept in open for a few days. The article when rubbed with toothpaste again starts shining.

i. Silver reacts with hydrogen sulphide gas present in air and forms a compound Ag2S. This compound is black in colour. Hence, silver articles turn black when kept in the...

1 Answers 1 views
a and b working together can do a work in 6 days.if A takes 5 days less than B to to finish the work in how many days B alone can can do the work

B alone finish work in x days A alone work in x - 5 A one day works= 1/(x-5) and B one day works = 1/x A+B one day work = 1/6 so, 1/(x-5)...

1 Answers 1 views
X