S3 Chemistry (metals)

1.
Copper(II) oxide and lead(II) oxide can be reduced by heating with charcoal using Bunsen flame.
Carbon dioxide gas is also formed in the reaction.

(Mercury(II) oxide and silver oxide can also be reduced by heating with charcoal using Bunsen flame. However, mercury and silver can be obtained by heating the metal oxide alone. Therefore, we often heating mercury(II) oxide or silver oxide alone with Bunsen flame to obtain the metal instead of heating with charcoal.)

(Zinc and iron cannot be obtained by heating their oxide with charcoal using Bunsen flame. The temperature required (> 1000oC) is much higher than that can be provided by a Bunsen flame.)

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2.
a.
copper(II) oxide + carbon → copper + carbon dioxide

b.
The black copper(II) oxide changes to reddish brown.

c.
No, aluminium oxide cannot be reduced using the same method.
The reactivity of aluminium is high. Therefore, the oxide of aluminium is very stable, and thus cannot be reduced by heating with carbon.
(Aluminium is extracted by electrolysis of molten aluminium oxide.)

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3.
a)
Gas syringe is required.
(Another method is to use a inverted test tube which is completely filled with water and placed in a water bath. Label a mark on the test tube. Water is collected in test tube over water. A fixed volume of hydrogen is collected with the meniscus meets the mark.)

b)
The more reactive the metal, the shorter is the time measured.

c)
The first reason is that some metals (such as copper and silver) do not react with dilute hydrochloric acid. Therefore, we cannot compare the reactivity of such metals using this method.
The second reason is that some very reactive metals (such as sodium and potassium) cause explosive reactions with HCl. It is extremely dangerous to put these metals into dilute hydrochloric acid.

1. zine iron lead copper Mecury silver can be reduced by heating with carbon using Busen flame.
All will form Metal and CO2.

2a CuO(s)+C(s)->Cu(s)+CO2(g)
b Shiny things will formed.
c No, aluminium oxide cannot be reduced to give the metal using the same method.It is because the reactivity of Al is too high that we can only use electrolysis to extract its metal.

3 a We can connect the test tube(with HCl and metal) to a trough by a delivery tube. And put a test tube filled with water on the trough.Put the delivery tube below the test tube. When the reaction happens, hydrogen gas will go inti the test tube. So we can fix a point on the test tube to measure the fixed volume of hydrogen.
b The higher the reactivity is, the faster the reaction rate is.
c It is because copper, mercury, silver platinum and gold have no reaction with HCl.