Photo AI
5 (a) When lithium is placed in water it reacts to form lithium hydroxide and hydrogen gas - Edexcel - GCSE Chemistry - Question 5 - 2016 - Paper 1
Question 5
5 (a) When lithium is placed in water it reacts to form lithium hydroxide and hydrogen gas. Describe what you would see during this reaction. (b) Magnesium and iron... show full transcript
Worked Solution & Example Answer:5 (a) When lithium is placed in water it reacts to form lithium hydroxide and hydrogen gas - Edexcel - GCSE Chemistry - Question 5 - 2016 - Paper 1
Step 1
When lithium is placed in water it reacts to form lithium hydroxide and hydrogen gas. Describe what you would see during this reaction.
Answer
During the reaction of lithium with water, you would observe effervescence, which is the release of hydrogen gas. This gas can be seen as bubbles forming at the surface of the water. Additionally, the lithium may move around on the surface of the water and produce heat, indicating a vigorous reaction. If the reaction is strong enough, there may be a slight flame due to the flammable nature of hydrogen.
Step 2
They both conduct electricity. Explain, in terms of their properties, how metals conduct electricity.
Answer
Metals conduct electricity due to the presence of free-moving electrons within their structure. When a potential difference is applied, these electrons can move easily through the metal, allowing for the conduction of electric current. This property is a result of the metallic bonding where electrons are delocalized, creating a 'sea of electrons' that facilitates conductivity.
Step 3
Magnesium is in group 2 of the periodic table. Iron is a transition metal. Both magnesium and iron can form salts. State a difference in the appearance of magnesium salts and iron salts.
Answer
Magnesium salts typically appear as white crystalline solids, such as magnesium sulfate or magnesium chloride. In contrast, iron salts, like iron(II) sulfate or iron(III) chloride, often appear green or brown due to the oxidation states of iron and the presence of colored ions.
Step 4
Describe and explain what you would see in each of these three reactions and what it would tell you about the relative reactivity of the halogens, bromine and iodine.
Answer
In the reaction between potassium chloride and chlorine, you would observe no significant change as chlorine does not react with potassium chloride. For potassium bromide, however, the reaction would yield a color change as chlorine displaces bromine, indicating that chlorine is more reactive than bromine. When potassium iodide is mixed with chlorine, a brown color would develop, indicating the displacement of iodine. This tells us that chlorine is the most reactive halogen, followed by bromine and iodine, which is the least reactive based on these observations.