Liquid vs Gas
Category: Pure Chemistry
Aqueous sodium carbonate vs aqueous sodium chloride
Paper Chromatography of Aspirin
Catalytic Converter
Speed of Reaction with Acids
The action of heat on metals and metal carbonates
Based on the data given, suggest which 2 were the metals and which 2 were the metal carbonates. Explain your answers.
Metals: A and D
Metal carbonates: B and C
Explanation:
Metals, when heated, will be oxidized by oxygen in the air to form metal oxides. The oxygen gained to form the oxide will cause the mass of the product formed to be higher. Mass increase for solids A and D after heating, so these two are metals.
Metal carbonates, when heated, can decompose to form metal oxides and carbon dioxide. The carbon dioxide formed escape to the surroundings, causing the mass of the solid product formed to be smaller.
The mass of B decreased after heating, so it must be one of the metal carbonates.
The mass and appearance of C remained unchanged, so it must be the other metal carbonate, which is not decomposed by the heat.
Explain how combustion engines produce nitrogen oxides.
Fuels are combusted in internal combustion engines, producing a lot of heat.
The high temperature condition causes oxygen and nitrogen in the air to react to form oxides of nitrogen.
Describe the pollution problems caused by the disposal of non-biodegradable plastics.
– Plastics are flammable.
In the event of a fire, plastic materials burn readily, causing the fire to spread quickly.
– Burning of plastics gives off toxic gases.
Many plastics produce poisonous gases upon incineration, causing air pollution.
– Plastics are non-biodegradable.
By “non-biodegradable”, it means that plastics cannot be decomposed by bacteria in the soil. Improper disposal of plastics can cause land and water pollution.
What are the applications of esters?
Esters are used:
– in the manufacture of perfumes
– in the manufacture of artificial food flavorings
– as solvents for cosmetics and glues
– in the manufacture of soaps
Why must the temperature be kept at 37 deg C during fermentation of glucose solution?
At 37 deg C, the enzymes in yeast are the most active, so fermentation process will be fastest.
At low temperatures, the enzymes in yeast are inactive, so fermentation will be slow.
At high temperatures, the enzymes in yeast will be denatured, so fermentation will stop.