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Facts related to mathematics
24/08/2025

Facts related to mathematics

COPPER (Cu)Copper is one of the less reactive metals and belongs to a group of elements known as the noble metals which ...
18/05/2025

COPPER (Cu)
Copper is one of the less reactive metals and belongs to a group of elements known as the noble metals which include silver and gold. It is very stable in air and can be found in the free metallic form in a few places. However, the principal source of the metal is copper pyrites, CuFeS2. Copper also also exists in the combined state as cuprite, Cu2O, malachite, CuCO3.Cu(OH)2, chalcocite, Cu2S, and bornite, Cu2S.Cu.FeS.

EXTRACTION
Copper is usually extracted from sulphide ores, such as copper pyrites, CuFeS2. The ore is concentrated by froth flotation. Then it is roasted in a limited supply of air to oxidize the iron and some of the sulphur in the ore to iron(II) oxide and sulphur IV oxide respectively.

2CuFeS2(s) + 4O2(g) ➡️ Cu2S(s) + 2FeO(s) + 3SO2(g)

Silicon IV oxide is added and the mixture is heated in the absence of air to convert the iron II oxide to iron II trioxosilicate (IV). The latter floats on copper (I) sulphide as slag and is removed.
FeO(s) + SiO2(s) ➡️ FeSiO3(s)

The copper I sulphide that remains is heated in a controlled amount of air to produce copper with a purity of about 97% - 99%.

Cu2S (s) + O2(g) ➡️ 2Cu(s) + SO2(g)

Where copper of high purity (99.95%) is required, the crude copper is made into anodes in an electrolytic cell containing pure copper cathodes and a copper II tetraoxosulphate VI solution and refined by electrolysis.

NITROGEN(II) OXIDE Nitrogen(II) oxide, NO was discovered by Cavendish in 1770 as one of the products formed on pa...
11/05/2025

NITROGEN(II) OXIDE
Nitrogen(II) oxide, NO was discovered by Cavendish in 1770 as one of the products formed on passing an electric spark through air. It is difficult to obtain the gas in the pure state because of its great affinity for oxygen. It reacts readily with oxygen even at ordinary conditions to form nitrogen(IV) oxide, NO2.

LABORATORY PREPARATION OF NO2
Nitrogen (II) oxide can be prepared by the action of trioxonitrate (V) acid on most metals. Usually, a 50% acid solution and coper turnings are used.

3Cu(s) ➡️ 8HNO3(aq) ➡️ 3Cu(NO3)2(aq) + 4H2O(l) +2NO(g)

Brown fumes of nitrogen (IV) oxide are always produced during the process, when some of the nitrogen(II) oxide formed reacts with the oxygen in the flask. However, nitrogen (IV) oxide is very soluble in water and so is removed when the gases are bubbled through water.
2NO(g) + O2(g) ➡️ 2NO2(g)

PHYSICAL PROPERTIES OF NO
i. It is neutral to litmus.
ii. It is slightly denser than air.
III. It is almost insoluble in water
IV. Nitrogen(II) oxide is a colourless, poisonous gas. It's smell is unknown because it changes immediately to nitrogen (IV) oxide on exposure to air.

TEST FOR NITROGEN (II) OXIDE
Common tests for nitrogen II oxide are:

a. On Exposure to Air: Remove the stopper of the test- tube containing the unknown gas and note what happens. If the gas turns reddish-brown on exposure to air, then it is probably nitrogen(II) oxide.

b. With Iron(II) tetraoxosulphate (VI): pour a solution of iron(II) tetraoxosulphate (VI), which has been acidified with a little dilute tetraoxosulphate(VI) acid, into a test-tube containing the unknown gas. If the solution turns dark brown, then the gas is nitrogen(ii) oxide

CARBON(II) OXIDE Carbon(II) oxide, CO, is an oxide of carbon , produced by the incomplete combustion of carbon compo...
11/05/2025

CARBON(II) OXIDE
Carbon(II) oxide, CO, is an oxide of carbon , produced by the incomplete combustion of carbon compounds, such as octane, C8H18, found in petrol.
2C8H18(l) + 17O2(g) ➡️ 16CO(g) + 18H2O(I)

Carbon(II) oxide occurs in traces as an impurity in the atmosphere. The percentage present may be higher in cities where the gas is released in the exhaust fumes of motor cars, and in industrial areas due to the combustion of fuels.

Carbon(II) oxide is a poisonous gas. As little as 0.5% of it in the air may cause a person to die. Since the gas has no colour or odour, its presence is difficult to detect, so it is very dangerous.

PREPARATION
Carbon(II) oxide is prepared from carbon IV oxide by passing the latter through red-hot carbon as shown in the set up. Most of the carbon IV oxide gets reduced to carbon(II) oxide. Unchanged carbon (IV) oxide is removed when the mixture of gases passes through concentrated sodium hydroxide. The pure carbon(II) oxide is collected over water.
CO2(g) + C(s) ➡️ 2CO(g)
Carbon II oxide can be prepared by dehydrating methanoic(formic) or ethanedioic(oxalic) acid, using concentrated tetraoxosulphate VI acid. The latter serves as a dehydrating agent.


H2SO4
CHOOH(I) ➡️ CO(g)
-H2O

CAUTION: The preparation of carbon(II) oxide must be done in a fume cupboard as the gas is poisonous.

PHYSICAL PROPERTIES
1. Carbon II oxide is a colourless, tasteless and odourless gas
2. It is insoluble in water, but dissolve in a solution of ammoniacal copper(I) chloride.
3. It is slightly less dense than air.
5. It is neutral to litmus

TEST FOR CARBON II OXIDE
Bubble some of the unknown gas through a test tube containing lime water. Next, apply a lighted splint to a test tube containing the unknown gas. Note what happens. The add some lime water to the test tube and shake.
If the gas is carbon II oxide, it will burn with a blue flame and turn lime water milky after burning

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