what type of elements can react with metals to form salts
CHEMISTRY: Class THREE: Topic 3 - ACIDS, BASES AND SALTS
TOPIC three: ACIDS, BASES AND SALTS
The Natural Sources of Acids and Bases
Investigate the natural sources of acids and bases
In everyday life, we deal with many substances that chemists classify every bit acids. For example, orange juice and grapefruit juice comprise citric acrid. These juices, and others of the like, contain ascorbic acid, a substance more than usually known every bit vitamin C. Examples of natural sources of acids and the type of acids they comprise are shown in table below.
Some natural sources acids
| Source | Type of acrid present |
| Mineral acids (HCl, H2SO4, HNO3, etc.) | Minerals |
| Tobacco | Salicylic acid |
| Tea | Tannic acrid |
| Coffee | Chlorogenic acid |
| Saccharide beet | Glutaric and adipic acids |
| Blackberry | Isocitric acid |
| Spinach, tomato | Oxalic acid |
| Sour (fermented milk) | Lactic acid |
| Bee, ant and nettle stings | Methanoic acid (formic acid) |
| Grapes, bananas, tamarinds | Tartaric acrid |
| Citrus fruits | Citric acid ( lemons and limes have particularly high concentrations of citric acid; information technology can constitute equally much as 8% of the dry out weight of these fruits) |
Acids accept a sour gustatory modality. Vinegar, lemon juice, grapefruit juice and spoilt or fermented milk are all sour tasting considering of the presence of acids. The acids nowadays in animal and plant materials are known asorganic acids.
Salads are often flavoured with vinegar, which contains dilute acetic acrid. Boric acrid is a substance that is sometimes used to wash the eyes.
In whatsoever chemistry laboratory, we notice acids such as hydrochloric acid (HCl), sulphuric acid (H2And thenfour), and nitric acrid (HNO3). These acids are called mineral acids considering they can be prepared from naturally occurring compounds called minerals. Mineral acids are more often than not stronger and should exist handled with not bad intendance, especially the concentrated acids, for they are very corrosive. They can swallow away metals, peel and article of clothing. Nevertheless, some acids are non corrosive even when they are concentrated. They are called weak acids. Ethanoic acrid is one instance. It is found in vinegar. In general, organic acids are weaker than natural acids.
You lot can tell if a substance is acid or not past its event on litmus. Litmus is a imperial dye. Information technology can be used as a solution, or on paper, called litmus paper.Litmus solution is purple. Litmus paper for testing acids is blue while that for testing bases is ruby-red in colour. Acids volition turn litmus solutionred. They will also turn bluish litmus newspaperred.
Bases do not unremarkably occur naturally. So they are not commonly obtained from natural sources. Even so, they are prepared in the laboratory or in industry. Bases can exist classified into oxides, hydroxides or carbonates. Therefore, bases tin can be defined equally the oxides, hydroxides or carbonates of metals. Bases gustatory modality bitter. A biting taste is a feature of all bases.
Virtually bases are insoluble in water. The bases which dissolve in water are known equallyalkalis. The most common alkalis are potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide, Ca(OH)2, and ammonium hydroxide (NHfourOH), too known every bit ammonia solution.
Alkalis turn litmus solutionblueish and red litmus paperblueish.A substance, such as litmus, which changes from one color to some other when mixed with an acrid or base, is chosen anindicator. Tabular array 3.ii shows how acids and bases (alkalis) touch on the colours of unlike indicators. Nosotros can utilize this clue of colour changes to tell whether an unknown substance is an acid or base (alkali).
Some common indicator colour changes
| Indicator | Colour in acrid | Colour in brine (base) |
| Methyl orange | orangish | yellow |
| Phenolphthalein | colourless | Pink |
| Litmus | carmine | blueish |
| Bromothymol blue | yellow | blue |
The Reactions of Acids with Various Materials
Determine the reactions of acids with various materials
Acids react with different substances to produce different products. These reactions are best carried out by using dilute acrid solutions. The following are some reactions of dilute acids with various substances.
The Reactions of Alkalis with Diverse Materials
Determine the reactions of alkalis with various materials
Alkalis react with acids to produce salt and water. All alkalis, except ammonia solution, will react with ammonium compounds liberating ammonia gas. Aqueous solutions of alkalis will precipitate the insoluble hydroxides of other metals from the solutions of metal salts. Caustic alkalis set on aluminium, zinc and lead to course salts. They react with carbon dioxide to form carbonates.
The Reactions of Bases with Diverse Substances
Determine the reactions of bases with various substances
Applications of acid-base neutralization in everyday life
Applications of acid-base neutralization in everyday life
Acrid-base neutralization has many applications in everyday life. The following are some of these applications:
An Indicator from Locally Available Materials
Explain an indicator from locally bachelor materials
Certain coloured substances (many extracted from plants) have been establish to change colour if added to an acid or alkaline solution. The color change is reversed if the acid or alkali is neutralized. Substances that comport like this are known as indicators.
Coloured extracts can be made from red cabbage or blackberries, but probably the most used indicator islitmus. This is extracted from lichens.
Litmus ispurple in a neutral solution. When added to an acid solution, information technology turnsred. Changing this red colour of litmus needs a chemic reaction. The molecules of the indicator are unremarkably changed in the presence of the acid. Substances with the contrary chemical effect to acids are needed to reverse the change, and these are called alkalis. They plough litmus solution toblue. Litmus tin can too be used in paper form, in which case information technology is calledlitmus paper. Here it comes in the blue and ruby forms. Litmus is a single chemical compound. Information technology gives a single colour change.
Litmus is not the simply single indicator that chemists find useful. Others that are used frequently arephenolphthalein andmethyl orange. These indicators give different colour changes when in acidic and alkaline metal solutions (see table 3.2).Some other commonly used indicator is theuniversal indicator (or full-range indicator). This is made from a mixture of dyes. Such an indicator is useful because information technology gives a range of colours ("spectrum") depending on the force of the acid or alkali added (come across table 3.3)
With a universal indicator, different acids produce a range of different colours. Indeed, solutions of the same acid with unlike concentrations (pH) requite different colours.
The more acidic solutions (for case bombardment acid) plough the universal indicatorbright red. A less acidic solution (for example vinegar) will only turn information technologyorange-yellow. At that place are as well colour differences produced with different brine solutions. The about alkaline solutions give aviolet colour while the less alkaline solutions give ablue colour.
We learned that many indicators are extracted from plants. Flowers and leaves of different plants have dissimilar colours. These plant organs may be used to prepare indicators locally.
The Acidity and Alkalinity of Substance Using Indicators
Test the acerbity and alkalinity of substance using indicators
The Concept of an Indicator
Describe the concept of an indicator
You lot have seen that single indicators change their colours only once when put in unlike acrid and alkaline solutions. The single indicators most commonly used include litmus, phenolphthalein and methyl orange.
On the other hand, universal indicators show a range of colour changes depending on the strength of an acrid or base.
Single indicators can just tell us whether a sure solution is an acrid or an alkali. These types of indicators cannot be used to compare 2 acids or two alkalis with unlike strengths. Litmus newspaper, for example, cannot exist used to compare the strengths of sulphuric acid and ethanoic acid. Both acids will change theblue litmus paper tored. As well, you cannot compare the strengths of aqueous ammonia solution (NH4OH) and sodium hydroxide by just using a litmus paper. They will both turn tored litmus paper to blue.
A universal indicator tin be used to measure strengths of different acids and alkalis. This indicator is a mixture of elementary indicators. Instead of changing colour just one time, it changes color a number of times depending on the degree of acerbity or alkalinity of the substances tested.
The pH calibration is a convenient means of expressing the acidity and alkalinity in liquids. The pH scale is a numerical scale used to bespeak the relative strengths of acidic or basic solutions in terms of relative corporeality of hydrogen ions (protons) or hydroxyl ions in solutions. The scale ranges from 0 to 14.
Acidic solutions will have pH values less than seven.0 and alkali metal solutions will accept pH values greater so vii.0. All neutral liquids eastward.thou. pure water have pH of seven.0. Table 3.3 shows the pH and strengths of acidic and alkaline solutions and the associated indicator colour changes.
Colours of the universal indicator in different acidic and alkaline solutions
| pH range | Colour | Forcefulness |
| i, 2, 3 | Red | Strongly acidic |
| 4 | Orange | |
| 5, 6 | Yellow | Weakly acidic |
| 7 | Green | Neutral |
| 8, 9 | Blue Indigo | Weakly alkali metal |
| 10, 11, 12, xiii, 14 | Purple/violet | Strongly alkaline |
Think that there is no articulate dividing line between the pH ranges as patently shown in the above table. This means that yous may have substances with, for example, pH 1.2, i.5, 3.v, four.iv, 5.6, 8.iv, etc. The tabular array merely tries to simplify the concept of acidity and alkalinity of acrid and alkaline solutions.
The Natural Source of Salts in Daily Life
Investigate the natural source of salts in daily life
A salt is a substance formed when some or all of the hydrogen atoms of an acid are replaced past a metal or ammonium ion. A table salt, therefore, may exist defined asa compound in which thereplaceable hydrogen of an acid has been wholly or partially replaced by a metal.
In sodium chloride (NaCl), for example, the hydrogen atom of hydrochloric acrid (HCl) has been wholly replaced by an atom of sodium. In magnesium sulphate (MgSOiv) and sodium sulphate (Na2SOfour), both hydrogen atoms of sulphuric acid (H2So4) accept been replaced by one cantlet of magnesium and two atoms of sodium respectively. In sodium hydrogen sulphate (NaHSO4), only one out of two hydrogen atoms has been replaced past an atom of sodium. This type of a salt is called an acid table salt, because it yet contains a replaceable hydrogen atom.
Many chemical compounds may be classified every bit salts. The common salt most familiar to every body is table common salt (sodium chloride). Baking soda is the salt, sodium bicarbonate (NaHCO3). Magnesium sulphate (also chosen Epsom salt) is often found in the home.
In full general, salts are ionic impounds that are composed of metal and not metallic ions. For instance, sodium chloride is is composed of metal sodium ions (Na+) and not-metallic chloride ions (Cl-). Some salts are made of metallic and non-metallic radicals due east.g ammonium nitrate (NHivNOthree) is composed of ammonium radical (NHfour +) and nitrate radical (NO3 -).
There is a wide range of types and natural sources of salts. Common common salt is mined from underground deposits. The table salt obtained from such a source contains sodium chloride mixed with stone impurities.
The other source of sodium chloride is seawater. The salty gustatory modality of seawater is due to the presence of salts such every bit sodium chloride and magnesium bromide. However, at that place are many unlike types of salts nowadays in seawater, though in small-scale proportions, as shown in the table below (table three.5)
| Salt | Formula | Percentage composition |
| Sodium chloride | NaCl | 2.72 |
| Magnesium chloride | MgCltwo | 0.38 |
| Magnesium sulphate | MgSO4 | 0.17 |
| Calcium sulphate | CaSO4 | 0.13 |
| Potassium chloride | KCl | 0.09 |
| Calcium chloride | CaCO3 | 0.01 |
| Magnesium bromide | MgBr2 | 0.01 |
Sodium nitrate (Republic of chile saltpetre), NaNO3 and calcium carbonate, CaCO3 are plant in secret deposits. Calcium carbonate occurs naturally every bit marble, limestone or chalk in the ground from which it tin be mined mechanically. What other natural sources of salts do y'all know?
The Solubility of Different Salts in the Laboratory
Analyse the solubility of different salts in the laboratory
Some salts are more soluble in water than others are. Nevertheless, other salts are insoluble in water. The knowledge of solubility of unlike salts in h2o is very important considering it tin can assist us gear up dissimilar salts in the laboratory by such methods as precipitation, direct combination (synthesis), crystallization and and so along.
Equally regards to solubilities, salts can be classified into two groups: salts which are soluble in water (soluble salts) and salts which practise non dissolve in h2o (insoluble salts). Table 3.half dozen summarizes the solubility of different salts in water.
The patterns of solubility for various types of salts
| Soluble salts | Insoluble salts |
| 1. All sodium, potassium and ammonium salts. | silver, mercury(I) and lead chlorides barium, lead (Two) and calcium sulphates but other common carbonates are insoluble.just other common hydroxides are insoluble. |
| 2. All nitrates of metals | |
| 3. All chlorides except .……………........ | |
| four. All sulphates except………………….. | |
| 5. Sodium, potassium, and ammonium carbonates…………………………... hydroxides………………………….…… | |
| half-dozen. Sodium, potassium and ammonium |
Salts in the Laboratory
Set up salts in the laboratory
Several methods are available for the preparation of salts. The solubilities of the prepared salts make up one's mind their methods of preparation. Hence, in the option of a method of preparation of a particular salt, one has to be acquainted with its solubility backdrop.
Soluble salts are usually prepared by methods which involvecrystallization. In this method, every bit the name suggests, resultant salts are in the grade of crystals.
Insoluble salts are usually prepared by methods which involveatmospheric precipitation. These methods are sometimes referred to every bit double decomposition. To precipitate an insoluble salt, you must mix a solution that contains its positive ions with the one that contains its negative ions.
Salts may also be prepared bydirect combination (or synthesis). For example, magnesium chloride may exist prepared in the laboratory by heating magnesium in a stream of chlorine.
Mg(southward) + Cl2(g) → MgCltwo(due south)
The Effects of Heat on Salts
Examine the effects of heat on salts
When different salts are heated, they behave in dissimilar manners. The crystals of some salts contain h2o of crystallization. When these hydrated salts are heated, their water of crystallization is driven off as steam. The crystals then lose their shape and become a powder. The following are few examples of hydrated salts:
| Table salt formula | Chemical name |
| CuSOiv.5H2O | Copper (II) sulphate five water |
| NatwoCO3.I0H2O | Sodium carbonate 10 water |
| MgCl2.6HtwoO | Magnesium chloride vi water |
| FeCl3.6H2O | Atomic number 26 (III) chloride six water |
| FeSO4.7H2O | Iron (II) sulphate seven h2o |
| CoCl2.6H2O | Cobalt (Two) chloride six h2o |
| MgSOiv.7HtwoO | Magnesium sulphate seven water |
| CaSO4.2H2O | Calcium sulphate 2 water |
The Uses of Different Types of Salts in Everyday Life
Explicate the uses of different types of salts in everyday life
There is a broad range of salts. A great number of them play an important role in our everyday life. The following are the uses of some salts:
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