3.2 Water

Beschreibung

GCSE Chemistry (.3 Air and water) Karteikarten am 3.2 Water, erstellt von Anisha Rai am 12/05/2016.
Anisha Rai
Karteikarten von Anisha Rai, aktualisiert more than 1 year ago
Anisha Rai
Erstellt von Anisha Rai vor mehr als 8 Jahre
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Zusammenfassung der Ressource

Frage Antworten
What does natural water contain? Dissolved salts which can be removed to obtain pure water
How can pure water be made? By distillation
What is desalination? An important method of obtaining water for domestic use in some countries
What is the boiling point of pure water? 100 degrees Celsius
Give a simple chemical test to show the presence of water Pure copper(II) sulphate is white. When water is present in a sample of copper(II) sulphate it turns blue. This colour change can be used to detect the presence of water (or water vapour).
What level of dissolved salts and microbes should there be in drinking water? Sufficiently low
How is water of the correct quality produced? By passing a suitable source through filter beds to remove solids, and then sterilising with chlorine
What do water filters contain that can remove some dissolved substances from tap water and improve taste and quality? Carbon, silver and ion exchange resins
How do ion exchange resins work? The resin beads have sodium ions attached to them. As the hard water passes through the column, the calcium and magnesium ions swap places with the sodium ions. The calcium and magnesium ions are left attached to the beads, while the water leaving the column contains more sodium ions. The hard water is softened because it no longer contains calcium or magnesium ions. Some ion exchange resins use hydrogen ions instead of sodium ions.
What are the argument FOR the addition of fluoride to drinking water Dental health improves Fluoride addition is sometimes viewed especially important in low-income areas, where access to non-water sources of fluoride (such as toothpastes) is limited to residents
What are the argument AGAINST the addition of fluoride to drinking water People have no choice in taking fluoride if it is in their water supply Consumption at higher levels over time has been proven to cause painful bone disease
Why might chlorine be added to drinking water? To reduce microbes
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