What colour does anhydrous copper(II) sulfate turn in the presence of water?
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What colour does anhydrous copper(II) sulfate turn in the presence of water?
Anhydrous copper(II) sulfate turns blue in the presence of water.
What colour does anhydrous cobalt(II) chloride turn in the presence of water?
Anhydrous cobalt(II) chloride turns pink in the presence of water.
Define the term pure substance.
A pure substance consists of a single element or compound.
Describe the physical test used to determine whether a sample of water is pure.
The physical test to determine whether a sample of water is pure is to check its boiling point which should be exactly 100 oC.
True or False?
Impurities tend to raise the boiling point of water.
True.
Impurities tend to raise the boiling point of water.
Name the piece of apparatus used to check the boiling point of water.
The piece of apparatus used to check the boiling point of water is a thermometer.
True or False?
Impurities tend to raise the melting point of water.
False.
Impurities tend to lower the melting point of water.
Why is distilled water used in practical chemistry?
Distilled water is used in practical chemistry because of its high purity, which prevents interference with chemical reactions.
List four substances that may be found in water from natural sources.
Four substances found in water from natural sources could include:
Dissolved oxygen
Metal ions (E.g. Ca2+, K+, Na+, Mg2+)
Plastics
Sewage
Harmful microbes
Nitrates from fertilisers
Phosphates from fertilisers and detergents
What are two beneficial substances found in water from natural sources?
Two beneficial substances found in water from natural sources are dissolved oxygen and some metal compounds.
Why is dissolved oxygen beneficial in water?
Dissolved oxygen is beneficial in water because it is essential for aquatic life.
Name two potentially harmful substances found in water from natural sources.
Two potentially harmful substances found in water from natural sources are sewage and some metal compounds.
What are nitrates and phosphates in water often sourced from?
Nitrates and phosphates in water are often sourced from fertilizers, with phosphates also coming from detergents.
True or False?
All metal compounds in water are harmful.
False.
Not all metal compounds in water are harmful.
Define eutrophication.
Eutrophication is a process where excess nutrients in water promote plant growth, leading to deoxygenation and damage to aquatic life.
What is the first step in the purification water?
The first step in the purification of water is filtration to remove large particles.
True or False?
Distillation is used in water purification.
False.
Distillation is not used in water purification.
What happens during sedimentation in water treatment?
Sedimentation allows heavy particles to settle at the bottom of the water treatment tanks.
What is the purpose of chlorination?
Chlorination is the process of adding chlorine to water to disinfect it by killing bacteria and other pathogens.
True or False?
Filtration removes dissolved impurities from water.
False.
Filtration removes large particles but not dissolved impurities.
True or False?
Bacteria can be removed by filtration alone.
False.
Bacteria are too small to be trapped by filters, which is why chlorination is necessary.
What types of impurities does untreated water contain?
Untreated water contains both soluble and insoluble impurities.
What are examples of soluble impurities in water?
Examples of soluble impurities in water include dissolved calcium, metallic compounds, and inorganic pollutants.
What are the three main steps of water treatment?
The three main steps of water treatment are sedimentation/filtration, filtration/treatment with carbon, and chlorination.
Why is carbon (charcoal) used in water treatment?
Carbon (charcoal) is used in water treatment to remove unpleasant tastes and odours.
What does NPK stand for in fertilisers?
In fertilisers, NPK stands for nitrogen, phosphorus, and potassium.
What is the role of nitrogen in plant growth?
Nitrogen in plant growth makes chlorophyll and protein, and promotes healthy leaves.
How does potassium benefit plants?
Potassium benefits plants by promoting growth and healthy fruit and flowers.
What is the main benefit of phosphorus for plants?
The main benefit of phosphorus for plants is promoting healthy roots.
Name two common ions that are sources of soluble nitrogen in fertilisers.
Two common ions that are sources of soluble nitrogen in fertilisers are ammonium ions (NH4+) and nitrate ions (NO3-).
What ion is a source of soluble phosphorus in fertilisers?
Phosphate ions (PO43-) are a source of soluble phosphorus in fertilisers.
True or False?
All potassium compounds used in fertilisers are insoluble in water.
False.
Most common potassium compounds used in fertilisers dissolve in water to produce potassium ions (K+).
Name three examples of common fertiliser compounds.
Three examples of common fertiliser compounds are ammonium nitrate (NH4NO3), ammonium phosphate ((NH4)3PO4), and potassium nitrate (KNO3).
True or False?
All fertilisers contain the same proportions of nitrogen, potassium, and phosphorus.
False.
Different fertilisers contain different proportions of nitrogen, potassium, and phosphorus.