A scum is formed, an insoluble precipitate which needs to be formed before the lather can form: sodium stearate and calcium ions makes calcium stearate and sodium ions
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What makes hard water hard?
Magnesium and Calcium ions
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Other than scum, what other problems occur when using hard water?
If the water is heated (say in a kettle) scale forms which is also an insoluble solid, this often builds up over the heating element of a kettle, reducing effieciency
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What are the benefits of hard water?
The calcium ions are good for bone growth and development, as well as teeth development and there is also a link to reduction in heart disease
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How can temporary hard water be softened?
By heating or boiling
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Other than heating, how else can hard water be softened?
Adding washing soda (sodium carbonate which reacts to form calcium carbonate which is a solid) or using a ion exchange column
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How does an ion exchange column work?
Made of a resin containing sodium or hydrogen ions, the calcium and magnesium exchange with the ions in the resin therefore softening the water. To replenish the resin sodium chloride can be added
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Why does temporary hard water soften when heated?
As it contains hydrogencarbonate ions, these decompose into carbonate ions which react with magnesium or calcium ions to form magnesium or calcium carbonates
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Other cards in this set
Card 2
Front
What happens when using soap with hard water?
Back
A scum is formed, an insoluble precipitate which needs to be formed before the lather can form: sodium stearate and calcium ions makes calcium stearate and sodium ions
Card 3
Front
What makes hard water hard?
Back
Card 4
Front
Other than scum, what other problems occur when using hard water?
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