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Questions and Answers
What is the objective of the experiment?
What is the objective of the experiment?
What is the purpose of adding phenolphthalein to the sodium hydroxide solution?
What is the purpose of adding phenolphthalein to the sodium hydroxide solution?
What happens to the colour of the solution when hydrochloric acid is added?
What happens to the colour of the solution when hydrochloric acid is added?
What is the purpose of using a burette in the experiment?
What is the purpose of using a burette in the experiment?
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What is the volume of the sodium hydroxide solution used in the experiment?
What is the volume of the sodium hydroxide solution used in the experiment?
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What is the purpose of shaking the conical flask?
What is the purpose of shaking the conical flask?
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What happens when the colour of the solution disappears?
What happens when the colour of the solution disappears?
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What is the purpose of using blue and red litmus papers?
What is the purpose of using blue and red litmus papers?
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What is the name of the apparatus used to add the acid drop by drop?
What is the name of the apparatus used to add the acid drop by drop?
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What is the purpose of closing the stop cock of the burette?
What is the purpose of closing the stop cock of the burette?
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Study Notes
Scientific Investigation
- A scientific investigation involves testing a hypothesis through experimentation and collecting data.
- The experiment involves lighting a candle, covering it with an inverted gas jar, and observing how it extinguishes when the oxygen in the air is used up.
- This proves that air is necessary for combustion or burning of substances.
Atomic Structure
- An atom is represented by the notation AZX, where X is the symbol of an element, Z is the atomic number, and A is the mass number.
- The number of neutrons in an atom is equal to the difference between the mass number and the atomic number (or proton number).
- A molecule is the smallest particle of an element or a compound that can exist freely in nature.
- Molecules of elements can be classified as monoatomic, diatomic, or polyatomic, and consist of only one type of atoms.
- Molecules of compounds consist of two or more different types of atoms.
Acids
- The general formula for acids is HnX, where X is a monoatomic or polyatomic anion combined with as many hydrogen ions as needed to make the anion electrically neutral.
- There are rules for naming acids based on the anion:
- If the anion name ends in -ide, the acid name begins with the prefix hydro-.
- If the anion name ends in -ite, the acid name is the stem of the anion with the suffix -ous, followed by the word acid.
- If the anion name ends in -ate, the acid name is the stem of the anion with the suffix -ic, followed by the word acid.
Investigating Acid Properties
- An experiment involves testing the effects of sulphuric acid on litmus paper and methyl orange.
- The procedure involves pouring dilute H2SO4 into test tubes, adding indicators, and observing color changes.
- The experiment is repeated using dilute HCl and HNO3 solutions.
Neutralization Reaction
- An experiment involves investigating the neutralizing effect of sulphuric acid on sodium hydroxide.
- The procedure involves setting up an apparatus, mixing sodium hydroxide solution with phenolphthalein, and adding hydrochloric acid drop by drop while shaking the flask.
- The experiment demonstrates the neutralization reaction of hydrochloric acid with sodium hydroxide, and the resulting solution does not affect the color of litmus papers.
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Description
Experiment to test the hypothesis that air is necessary for combustion, by observing the effect of oxygen availability on a burning candle. Analyze the results and draw conclusions.
