Water Flashcards
What is permanent hard water?
Calcium and magnesium ions from some salts, such as sulfates, are not removed by heating
What is temporary hard water?
Water that have it’s hardness removed by boiling it
What’s is the difference between hard and soft water when mixed with soap?
Soft water forms a lather easily and does not produce scum. Hard water reacts with soap to form scum, however this is not a problem when washing clothes because of soap less detergents.
How is hard water formed?
When the water flows over rocks containing magnesium or calcium compounds, such as calcium sulphate.
Why is the rain slightly acidic and what effect does it have?
Because the rain mixes with carbon dioxide as it falls making it slightly acidic. Calcium carbonate makes water hard but is practically insoluble in water however, the calcium carbonate mixes with the weak acidic water and the calcium hydrogen carbonate produced is soluble in the water- making the water hard
What causes the scum?
When magnesium and calcium ions in hard water react with the soap
How does hard water waste soap?
Because only once all the magnesium and calcium ions have reacted to form scum, can the soap form a lather, there the soap need to get rid of the ions is wasted
Why does li scale make electric appliances less efficient?
Because it covers the heating element and scale is a poor conductor of energy so it takes longer for the water to heat up, wasting energy
How was heating water move the hardness?
When heated, the hydrogencarbonaten ions within the water decompose. The carbonate ions then react with calcium or magnesium ions in the water which Is scale. However it’s very expensive and a waste of energy.
How does washing soda remove hardness?
It’s solvable carbonate ions precipitate out calcium and magnesium ions. These produce calcium and magnesium carbonates which are insolvable precipitates.
Why do we not distill our water to make it pure?
Because it would be very expensive to heat and condense large amounts of water.
What are carbon silver and an ion exchange resin used to make water drinkable?
Carbon reduces the levels of chlorine as well as pesticides and other impurities. Silver is used to stop to stop growth of bacteria. And the ion exchange resin is used to get rid off magnesium and calcium ions.
How does purifying water take place?
As water enters through plant it passes through a screen to remove objects. Then a settlement tank. Next aluminium sulphate and lime are added to clump together dirt into sludge. Water is then passed through fine sand which removes insolvable objects.chlorine is added. Ph is corrected and also fluorine added.
Why can temporary hard water be softened?
Because it contains hydrogencarbonate ion which decompose to give carbonate ions which react with the calcium and magnesium ions to form a precipitate.
How do water filters clean water?
1.the carbon in the filter reduces the levels of chlorine and pesticides 2. Silver discourages the growth of bacteria in the filter 3. Ion exchange column removes unwanted ions
