Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples…
Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded.
Answer the following questions :
(a) When activity was done with dilute hydrochloric acid, then in which one of the test tubes was the rate of formation of bubbles the fastest and the thermometer showed the highest temperature ?
(b) Which metal did not react with dilute hydrochloric acid ? Give reason.
(c) (i) Why is hydrogen gas not evolved when a metal reacts with dilute nitric acid ? Name the ultimate products formed in the reaction.
Solution
(a) In the test tube containing magnesium.
(b) All three metals react with HCl because they are more reactive than hydrogen.
(Award marks if student write any less reactive metal with reason)
(c)(i) Because HNO3 is a strong oxidizing agent and oxidizes the H2 produced to water.
Ultimate products are water, oxides of nitrogen.