Class 10:Acid Bases and Salts Notes

CHAPTER 2:

ACIDS BASES AND SALTS

• The sour and bitter tastes of food are due to acids and bases present in them.
• Acids are sour in taste whereas base are bitter in taste.

PROPERTIES OF ACIDS:

• The term acid has been derived from the Latin word ‘acidus’ which means sour.
• Acids have sour taste.
• Acids turn blue litmus to red.
• Acids give H⁺ ions in aqueous solution.
• Strong acids: HCl , H₂SO₄ , HNO₃
• Weak acids: CH₃COOH , Oxalic acid , lactic acid
• Concentrated acids: More amount of acid + less amount of water.
• Dilute acids: More amount of water + less amount of acid.

PROPERTIES OF BASES:

• Bases are the substances which are bitter in taste and soapy in touch.
• Bases turn blue litmus to red.
• Bases give OH^- ions in aqueous solution.
• Strong bases: NaOH , KOH , Ca(OH)₂
• Weak bases: NH₄OH
• Alkalis: these are bases which are soluble in water. Examples : NaOH , KOH , Ca(OH)₂

CHEMICAL PROPERTIES OF ACIDS:

(1)Reaction of acids with metal

• Metals on reaction with acids displaces hydrogen gas from acids and also forms a compound called salt.

Acid   +   Metal   →  Salt    +    Hydrogen gas

For example

2HCl     +    Zn   →     ZnCl₂     +     H₂

(2)Reaction of acids with metal carbonates

• Acids on reaction with metal carbonates and metal hydrogen carbonate forms salt, carbon dioxide and water.
• Metal carbonate/Metal hydrogen carbonate + acid  → Salt  + carbon dioxide + water

For example

Na₂CO₃   +   2HCl   →  2NaCl  +  H₂O   + CO₂

NaHCO₃  +  HCl   →  NaCl  +  H₂O   + CO₂

(3)Reaction of acids with base

• Reaction of acids with base gives salt and water.
• The reaction between acid and a base to give a salt and water is known as a neutralisation reaction.

Base + acid →  salt + water

For example,

NaOH + HCl → NaCl + H₂O

(4)Reaction of metallic oxide with acids

• Metal oxides on reaction with acids gives out salt and water.

Metal oxide + acid → salt + water

For example,

CuO  +2HCl  →  CuCl₂   + H₂O

CHEMICAL PROPERTIES OF BASE:

(1)Reaction of base with metal

• Metals on reaction with bases also forms salt and liberate hydrogen gas.

Base  +   Metal   →   Salt   +   Hydrogen gas

For example,

2NaOH   +   Zn    →    Na₂ZnO₂ (sodium zincate)  + H₂

(2)Reaction with metal carbonate/metal hydrogen carbonate

• Bases do not react with metal carbonate and metal hydrogen carbonate.

(3)Reaction of metallic oxides with base

• Metallic oxides do not react with base.

(4)Reaction of non-metallic oxides with base

• Non metallic oxides when react with base, it forms a salt and water

For example,

CO₂   +   Ca(OH)₂   →     CaCO₂   +   H₂O

WHAT DO ALL ACIDS AND BASES HAVE IN COMMON?

• All the acids have similar chemical properties like all acids generate hydrogen gas on reacting with metals. So we can say that hydrogen is common to all acids.
• If we perform an activity with some compounds that they could enable the current to pass through them or not, we will find that there is a flow of current through acid solution only. This current is carried through the solution by ions.
• Since the cation present in acids is H⁺, this suggests that acids produce hydrogen ions in solution which are responsible for their acidic properties.

TYPES OF INDICATORS AND THEIR PROPERTIES:

Indicators: Substances which change their colour/smell in different types of substances ( like acids and bases)

Types of Indicators:

1.  Natural indicators
2. Synthetic indicators
3. Olfactory indicators

Natural indicators: Found in nature in plants. For example, litmus ; red cabbage leaves extract ; flowers of hydrangea plant ; turmeric.

Synthetic indicators: These are chemical substances. For example, methyl orange ; phenolphthalein

Olfactory indicators: These substances have different odour in acids and bases.

WHAT HAPPENS TO AN ACID OR BASE IN A WATER SOLUTION?

• Acids in water solution dissociates H⁺ ions. Let us consider the reaction between water and hydrochloric acid (HCl). HCl in presence of water produces H⁺ ions. This ion cannot exist alone and hence combines with water molecules and forms H₃O⁺. The reaction is as follows:

HCl   +  H₂O   →   H₃O⁺    +  Cl^-

• Base when dissolved in water produces OH^- ions. Let us consider the reaction between water and sodium hydroxide NaOH. NaOH in presence of water produces OH^- ions. The reaction is as follows:

NaOH   +   H₂O   →   Na⁺    +   OH^-

• Dilution: mixing an acid or base with water results in decrease in the concentration of ions (H₃O⁺ / OH^-) per unit volume. Such a process is called dilution and the acid or the base is said to be diluted.

CAN ACIDS AND BASES CONDUCT ELECTRICITY?

Acids and bases exhibit their conducting properties only if they are in aqueous solution in which they could completely ionize in water,. An acid in water solution dissociates H⁺ ions.

pH SCALE

• A scale developed to measure the concentration of hydrogen ion in a solution is known as pH scale.
• pH scale ranges from 0 – 14.
• pH of neutral solution is 7.
• pH of acidic solution is less than 7.
• pH of basic solution is greater than 7.

HOW STRONG ARE ACID OR BASE SOLUTIONS?

• An increase in OH^- ions concentration in the solutions results in increase in the strength of alkali, hence the value of pH increases.
• Acids giving rise to more H⁺ ions are strong acids whereas those giving rise to less H⁺ ions are termed as weak acids.
•  Bases giving rise to more OH^- ions are strong bases whereas those giving rise to less OH^- ions are termed as weak bases.

ARE PLANTS AND ANIMALS Ph sensitive?

• Plants require a specific pH rage for their healthy growth. When pH of rain water is less than 5.6, it is called acid rain that lowers the Ph of the river water and makes it difficult for marine creatures to survive.
• Our body works within the pH range of 7.0 -7.7. The pH of saliva ranges from 6.5 – 7.5 .

Ph OF OUR DIGESTIVE SYSTEM?

·         Our stomach produces hydrochloric acid, which helps in the digestion of food without harming the stomach. But during indigestion an excess amount of acid is produced causing pain and irritation.

Ph CHANGE AS THE CAUSE OF TOOTH DECAY?

• Tooth decay starts when the pH of the mouth is lower than 5.5
• Tooth enamel made up of calcium hydroxyapatite ( a crystalline form of calcium phosphate) is the hardest substance in human body.
• The enamel does not dissolve in water but get corroded when the pH in the mouth is below 5.5
• Bacteria present in mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating.

SELF DEFENCE BY ANIMALS AND PLANTS:

•  Bee sting leaves an acid (formic acid) which causes pain and irritation.
•  Stinging hair of nettle leaves inject methanoic acid causing burning pain.
• Use of a mild base like baking soda on the stung area can provide relief to some extent due to neutralization reaction between acid and base.

SOME NATURALLY OCCURING ACIDS:

Vinegar, orange , tamarind, tomato , curd, lemon, ant sting, nettle sting, acetic acid, citric acid, tartaric acid, oxalic acid, lactic acid, citric acid , formic acid , methanoic acid.

Ph OF SALT :

•  Salts of strong acid and a strong base are neutral with pH value of 7.
•  Salts of strong acid and weak base are acidic with pH value less than 2.
•  Salts of weak acid and strong base are basic with pH value more than 7.

COMMON SALT:

• Salt formed by the blend of hydrochloric acid and sodium hydroxide solution is called sodium chloride (common salt).
• The salt we commonly consume is neutral.
• This neutral common salt acts as a preliminary raw material for extracting several other materials of daily use like sodium hydroxide, baking soda, washing soda , bleaching powder etc.

MANUFACTURE OF SODIUM HYDROXIDE:

• Passing electricity through brine solution (an aqueous solution of sodium chloride), decomposes it to give chlorine and sodium hydroxide.
•  The process is termed as the chlor-alkali process. The term chlor is for chlorine and alkali is for sodium hydroxide.
• Chlorine gas is given off at anode and hydrogen gas at the cathode.
• Sodium hydroxide solution is formed near the cathode.
•  2NaCl  +   2H₂    →   2NaOH   +  Cl₂    +    H₂

IMPORTANT PRODUCTS OBTAINED FROM THE CHLOR-ALKALI PROCESS :

• HYDROGEN: used as fuels, margarine, ammonia for fertilisers.
• CHLORINE: used for water treatment in swimming pools, in PVC, in disinfectants, in CFC’s, pesticides.
• NaOH: used for de-greasing metals, soaps and detergents, paper making, artificial fibres.
•  Hydrochloric acid is used for cleaning steel, ammonium chloride, medicines, and cosmetics. 
• Chlorine and NaOH as bleach are used in household bleaches and bleaching fabric.

BLEACHING POWDER:

•          Chlorine produced on passing electricity through brine solution undergoes reaction with dry slaked lime [Ca(OH)₂] to  produce bleaching powder.
•          The reaction is as follows:

                       Ca(OH)₂      +    Cl₂     →      CaOCl₂    +   H₂O

•          This bleaching powder is used for several purposes:

(i)      As a bleaching agent for bleaching cotton and linen in the textile industry.

(ii)    To bleach washed clothes in laundry.

(iii)   As an oxidising agent in many chemical industries.

(iv)  To disinfect drinking water and make it germ free.

BAKING SODA:

•          Chlorine produced on passing electricity through brine solution undergoes reaction with ammonia produces baking soda.
•          The chemical name of baking soda is sodium hydrogen carbonate (NaHCO₃).
•          It is a mild non-corrosive basic salt.
•          The following reaction take place:
•  NaCl   +   H₂O   +   CO₂   +   NH₃   →   NH₄Cl    +    NaHCO₃

Syllabus of UPTET for Junior Level Examination

Syllabus for UPTET Junior Level

Number of questions: Total 150 questions

Number of Sections in Exam: 4 sections

No Negative Marking

Choice of Paper: Candidates have to choose from mathematics and science or social science as per their stream

Section	Maximum Questions	Maximum Marks
Child development and Pedagogy	30	30
1st Language	30	30
2nd Language	30	30
Science & Maths OR Social studies	60	60
Total	150	150

Section 1: Child development and pedagogy

(A). Child Development (बाल विकास) Topic (15 Questions):

• Development Concepts and its relationship with learning (विकास की अवधारणा और इसका सीखने के साथ संबंध)
• Influence of Heredity and Environment (आनुवंशिकता और पर्यावरण का प्रभाव)
• Principles of the development of children (बच्चों के विकास के सिद्धांत)
• Socialization Processes: Social World and Children (Teacher, Parents and Peers) (समाजीकरण की प्रक्रिया: सामाजिक दुनिया और बच्चों (शिक्षक, माता पिता,एवं साथी))
• Kohlberg, Piaget and, Vygotsky: Constructs and Critical Perspectives
• Multidimensional Intelligence (चहुँ ओर बौद्धिक विकास)
• Language & Thought (भाषा और विचार)
• Critical perspective of the construct of Intelligence (बौद्धिक विकास के लिए गुणात्मक विवेचन)
• Concepts of Child Oriented and Progressive Education (बच्चों को केंद्रित करते हुए प्रगतिशील शिक्षा की अवधारणा)
• Gender as a social construct: Gender Roles, Gender Bias and Educational Practice (एक सामाजिक निर्माण के रूप में ; लिंग भूमिकाओं, लिंग-पूर्वाग्रह,  लिंगी भेद और शैक्षिक अभ्यास)
• Distinction Between Assessment for learning and assessment of Learning; Continuous & Comprehensive Evaluation, School Based Assessment, Perspective and Practice,  (सीखने और सीखने के आकलन, नजरिए और व्यवहार के बीच भेद,  स्कूल आधारित मूल्यांकन, सतत एवं व्यापक मूल्यांकन),
• Formulating appropriate questions for assessing readiness levels of learners शिक्षार्थियों की तत्परता के स्तर के आकलन करने के लिए; For Enhancing/improve the learning and critical thinking of classroom and for assessing learner achievement. (सीखने और कक्षा में महत्वपूर्ण सोच को बढ़ाने के लिए और शिक्षार्थी की उपलब्धि का आकलन करने के लिए उचित प्रश्नों का प्रतिपादन)

(B) Concept of Inclusive Education and Understanding Children with Special Needs (समावेशी शिक्षा की अवधारणा और बच्चों की समझ का आकलन) (05 Questions):

• Addressing the Creative, Talented, specially abled Learners,(बुद्धिमान, रचनात्मक, विशेष रूप से विकलांग शिक्षार्थियों का संबोधन)
• Addressing the requirements of children with learning difficulties ‘impairment’, etc (सीखने की कठिनाइयों, दुर्बलता आदि के साथ बच्चों की जरूरतों का संबोधन)
• Addressing learners from diverse backgrounds including the Deprived and Disadvantaged (विभिन्न पृष्ठभूमि से संबंध रखते शिक्षार्थी सुविधाहीन और वंचित शिक्षार्थियों को पढ़ना)

(C) Learning and Pedagogy (शिक्षा और अध्यापन): 10 Questions will be asked from following topics:

• How children think and learn, How and why children failed to achieve success in school performance (कैसे बच्चे सोचते और सीखते हैं; कैसे और क्यूँ वे स्कूल में सफलता प्राप्त करने में असफल होते हैं |)
• Basic processes of teaching and learning शिक्षण और सीखने की बुनियादी प्रक्रियाओं;, {Children’s Strategies of Learning सीखने के बच्चों की रणनीति;, Learning as a Social Activity एक सामाजिक गतिविधि के रूप में सीख; , Social Context of Learning शिक्षा का सामाजिक संदर्भ}
• Child as a problem solver (समस्या का हल निकलने वाले) and a ‘scientific investigator (एक ‘वैज्ञानिक अन्वेषक’ के रूप में बच्चे)
• Factors contributing to learning (सीखने के लिए योगदान के कारक) – personal and environmental (व्यक्तिगत और पर्यावरण)
• Motivation and Learning (प्रेरणा और सीख)
• Cognition and Emotions (अनुभूति और भावना)
• Alternative Conceptions of Learning in Children बच्चों में सीखने की वैकल्पिक धारणाएं, Understanding children ‘errors’ as significant steps in the learning process सीखने की प्रक्रिया में बच्चों की ‘त्रुटियों’ को महत्वपूर्ण कदम के रूप में समझना)

Section 2: English Language

Comprehension (15 Questions): Two unseen prose passages will be given in question paper and questions will be related to grammar and verbal ability, passages. Passage will be following types – Discursive or literary or narrative or scientific, etc.

Pedagogy of Language Development (15 Questions): It will cover questions from following topics:

• Principles of Language Teaching
• Role of speaking & listening; Function of Language and how children use it as a tool
• Learning and Acquisition
• Evaluation Language comprehension and proficiency: listening, speaking, writing and reading.
• Challenges of teaching language in a diverse classroom; language difficulties, errors and disorders
• Critical perspective on the role of grammar in learning a language for communicating ideas verbally and in written forms
• Remedial Teaching
• Teaching Learning Materials: Text Books, Multimedia materials, multilingual resources of the classroom

Section 3: Hindi Language

भाषा समझ (15 सवाल): एक गद्य या नाटक या एक कविता समझ पर प्रश्न पूंछे जाते है जिसमे, हिंदी व्याकरण, अनुमान और शाब्दिक क्षमता से सम्बंधित प्रश्न भी होते है (गद्य पठांश साहित्यिक, वैज्ञानिक, असंबद्ध या कथा इत्यादि से हो सकता है)

भाषा विकास का अध्यापन: (15 सवाल)

• भाषा शिक्षण के सिद्धांत
• सीखना और अधिग्रहण
• सुनने और बोलने की भूमिका;
• भाषा के प्रयोग और कैसे बच्चों के लिए उपयोगी है
• भाषा को सीखने और अपने विचारों को मौखिक या लिखित रूप में व्यक्त करने के में व्याकरण की भूमिका
• विभिन्न कक्षाओं में भाषा के शिक्षण की चुनौतियाँ;
• भाषा की त्रुटियां और विकार
• भाषा कौशल
• भाषा की कठिनाइयाँ
• उपचारात्मक शिक्षण
• भाषा समझ और प्रवीणता का मूल्यांकन: बोलने, सुनने, पढ़ने और लिखने के द्वारा
• शिक्षण अधिगम सामग्री: पाठ्यपुस्तक, मल्टी मीडिया सामग्री, कक्षा के बहुभाषी संसाधन

Section 4: Science and Maths / Social Science