What is a hardness in chemistry?

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Hardness is how resistant a mineral is to scratching, not how easily it breaks. Hardness depends on the bonds within the mineral, so the stronger the bonds, the harder the mineral. Mineral hardness is measured on the Mohs scale of hardness, which compares the hardness of different minerals (Fig. 1.11).

Why is it called hardness of water?

Water can either be hard, or soft. Hard water does not describe the actual feeling of the water. Instead, it is called hard water because it has has mineral deposits like calcium and magnesium within the water molecules.

What is hardness of water and types?

Hardness of water can be of two types temporary and permanent hardness. Temporary hard water contains only bicarbonates of magnesium and calcium. It can be removed by boiling. Permanent hard water contains chlorides and sulfates of calcium and magnesium.

What is water hardness formula?

The amount of hardness is expressed in milligrams per litre (mg/L) or grains per gallon (gpg) as calcium carbonate. Hardness is calculated from the equation Hardness = 2.497 (Ca) + 4.118 (Mg).

What is unit of hardness?

The SI unit of hardness is N/mm². The unit Pascal is thus used for hardness as well but hardness must not be confused with pressure. The different types of hardness discussed above have different scales of measurement.

What is the unit of hardness of water?

How is water hardness measured? Hardness is usually expressed in terms of the equivalent quantity of calcium carbonate (CaCO3) in milligrams per litre or parts per million. You may also see hardness expressed as Degrees of hardness in Clark (English) degrees, French or German degrees.

What are the two types of hardness?

  • Temporary Hardness.
  • Permanent Hardness.

Why is water hardness important?

But hard water can have some benefits, too. Humans need minerals to stay healthy, and the World Health Organization (WHO) states that drinking-water may be a contributor of calcium and magnesium in the diet and could be important for those who are marginal for calcium and magnesium intake.

What is the pH of hard water?

Water that is considered hard or alkaline has a pH level 8 or greater.

What is soft water in chemistry?

soft water, water that is free from dissolved salts of such metals as calcium, iron, or magnesium, which form insoluble deposits such as appear as scale in boilers or soap curds in bathtubs and laundry equipment.

What is water hardness PDF?

It is a measure of the quantity of divalent ions (for this discussion, salts with two positive charges) such as calcium, magnesium and/or iron in water. There are many different divalent salts; however, calcium and magnesium are the most common sources of water hardness.

What is the chemical name of hard water?

Hard water also forms deposits that clog plumbing. These deposits, called “scale”, are composed mainly of calcium carbonate (CaCO3), magnesium hydroxide (Mg(OH)2), and calcium sulfate (CaSO4). Calcium and magnesium carbonates tend to be deposited as off-white solids on the inside surfaces of pipes and heat exchangers.

What is EDTA water hardness?

Hardness of water is determined by titrating with a standard solution of ethylene diamine tetra acetic acid (EDTA) which is a complexing agent. Since EDTA is insoluble in water, the disodium salt of EDTA is taken for this experiment. EDTA can form four or six coordination bonds with a metal ion.

What does hardness depend on?

8.3. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. Common examples of hard matter are ceramics, concrete, certain metals, and super hard materials, which can be contrasted with soft matter. Figure 8.41.

What are examples of hardness?

Hardness is a measure of how much a material resists changes in shape. Hard things resist pressure. Some examples of hard materials are diamond, boron carbide, quartz, tempered steel, ice, granite, concrete. Ability of material to resist wear, tear, scratching, abrasion cutting is called hardness.

What is another term for hardness?

The quality or condition of being physically hard or rigid. firmness. stiffness. rigidity. solidity.

How do we measure hardness?

A hardness test is typically performed by pressing a specifically dimensioned and loaded object (indenter) into the surface of the material you are testing. The hardness is determined by measuring the depth of indenter penetration or by measuring the size of the impression left by an indenter.

What increases water hardness?

Hardness can be increased in culture water by addition of several compounds such as calcium chloride and calcium sulfate. Calcium chloride has the further advantage of adding chloride, another physiologically active ion, to the culture water (see Chapter 3 and section 10.4. 3).

What is ppm water?

This is an abbreviation for “parts per million” and it also can be expressed as milligrams per liter (mg/L). This measurement is the mass of a chemical or contaminate per unit volume of water.

Can you drink hard water?

The bottom line. Most people can safely drink hard or soft water with no side effects. Higher sodium levels in soft water may be a concern for some people, but that can be managed with a potassium-based softening system.

What is EDTA method?

The classic method of determining calcium and other suitable cations is titration with a standardized solution of ethylenediaminetetraacetic acid (EDTA). EDTA has the structure shown below. Instead of repeatedly drawing this structure or writing out the chemical formula, the EDTA molecule is represented as “H4Y”.

What are the effects of hardness of water?

Hard water can interfere with the action of soaps and detergents and can result in deposits of calcium carbonate, calcium sulphate and magnesium hydroxide (Mg(OH)2) inside pipes and boilers, causing lower water flows and making for less efficient heating.

How is hardness of water removed?

Removal of hardness of water A few methods to remove hardness from water are, Chemical Process of Boiling Hard Water. Adding Slaked Lime (Clark’s Process) Adding Washing Soda.

What is water hardness and how is it measured?

Water hardness is measured in “grains” per gallon, in milligrams of calcium (Ca) per liter, or parts per million, and German Degrees of Hardness (dH) [which we drop here as this is for fish tanks]. You can take a water sample to a water test lab to have its hardness measures.

What is pH full form?

The full form of pH is Potential of Hydrogen. pH is known as the negative logarithm of H+ ion concentration. Hence the meaning of the name pH is explained as the strength of hydrogen. pH describes the concentration of the hydrogen ions in a solution and it is the indicator of acidity or basicity of the solution.

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