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30 Cards in this Set

  • Front
  • Back

State the chemical composition of water?

2 parts hydrogen 1 part oxygen. Rarely pure. Contains gases.

Is rainfall pure H20?

No.

Why is rainfall considered slightly acidic?

Because it absorbs gases and dusts through the atmosphere when it falls.

State 2 places where you would find a wholesome supply of water?

Spring water and deep well water

State 2 places where you find a suspicious supply of water?

Stored rainwater and surfaced water from cultivated lands.

State 2 places where you would find a dangerous supply of water?

River water to which sewage gains access and shallow well water.

Are surface waters generally hard or soft?

Surface waters are generally soft.

What causes water to become hard?

The type of ground the water comes into contact with.

What causes water to become temporarily hard?

Water soaks below ground and comes into contact with rock such as limestone. Salts are dissolved by the water and depending upon amount of carbon dioxide present in the water it can hold these salts in suspension.

What causes water to become permanently hard?

Water passes through sandstone the salts are readily dissolved and held in the water without the need for carbon dioxide.

Why is the name temporary given to temporary hard water?

Because this type of hardness can be removed by heating the water above 55°C.

What effect has soft water on plumbing systems?

It is corrosive therfore will damage pipes.

What effect as temporary hard water on plumbing systems

Causes scale, causes scumming

List the disadvantages of permanent hard water?

Causes scumming, skin irritations, heavy on soap and stains ware.

Explain the term furring?

Rock particles attaches itself to system boilers and inside pipework.

Explain the term scaling?

Means the same of furring

At what temperature does temporary hard water begin to cause furring?

55°C

State 4 problems caused by furring?

Reduce efficiency, cause kettling, reduce boiler life and reduce pipe bore

List 4 other effects hardness will cause?

Hard to get lather from soap, skin irritations, stains cutlery and causes ugly grey scum on cutlery.

Is permanent water really water that is permanently hard?

No it can be removed chemically by adding washing soda or using a water softener

List 2 disadvantages of soft water?

Can be corrosive and has a poor taste

List 2 advantages of soft water?

No scale and no staining

What are the disadvantages of hard water?

Causes scumming, heavy on soaps, skin irritations, dulls delph and stains ware.

What water can cause skin irritations?

Hard water causes skin irritations.

What should be fitted to a water softener to allow normal water supply during softener servicing?

A bypass

Explain the differences between permanent and temporary hard waters?

Temporary hard water can be removed by heating. Permanent hard water cannot be removed by heating. Temporary hard water causes scale. Permanent hard water does not cause scale.

How would you treat soft water?

Add controlled amounts of lime to the water to increase its alkalinity.

How would you treat hard water?

By fitting water softeners or fitting chemical conditioners.

What is the weight of 100 litres of water at 4°C?

100 kg

What is the continuous process of evaporation and condensation known as?

The Water Cycle.