Questions and Answers
What is the main purpose of applying heat in organic chemical reactions?
To speed up the reactions
Why are organic compounds with low boiling points volatile?
Because they evaporate when heated
What should you do if you spill chemicals on your body?
Stand directly under the shower and pull the lever immediately to flush the affected area with plenty of water for 15 minutes.
What is the term used to describe the arrangement in which a reaction is carried out in a boiling solvent with the vapour being condensed and returned to the reaction vessel?
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What is the purpose of the water sprayers in a chemistry lab?
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What is the purpose of the condenser in a reflux set-up?
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What is the difference between reflux and distillation?
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What should you do if you get chemicals in your eyes?
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Why is it important to be familiar with chemical hazard symbols?
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Why is it essential to ensure the condenser is completely filled with water?
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What happens to the vapours given off from the liquid reaction mixture in a reflux set-up?
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What is a key safety precaution when working with flammable and combustible liquids?
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What should you do with contaminated clothing, jewellery, and shoes when treating a chemical spill?
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What is the ultimate goal of using reflux in a chemical reaction?
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Why should you not place flammable and combustible liquids near open flames and spark-producing equipment?
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What should you do with storage areas for flammable and combustible liquids?
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What are the three main ways to make chemical processes 'greener'?
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Why is it necessary to find an alternative to A or B in the reaction A + B → C + D if C is the only desired product?
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What is the advantage of using alternative oxidising agents instead of chlorination for disinfecting water?
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What does a high atom economy of a reaction indicate?
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What is the formula to calculate the atom economy of a reaction?
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Why do industrial processes aim to have high atom economy?
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What is the atom economy of the reaction Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)?
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Why is it important to consider atom economy in chemical reactions?
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What percentage of an element is represented by its relative atomic mass?
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In a mixture of two isotopes, how do you calculate the percentage abundance of one isotope if you know the relative atomic mass and the percentage abundance of the other isotope?
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What is the formula used to calculate the relative atomic mass of an element?
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If an element has two isotopes with masses 20 and 22, and the relative atomic mass is 20.18, how would you calculate the percentage abundance of each isotope?
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Why do the percentages of the isotopes in a mixture add up to 100%?
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What information is needed to calculate the relative atomic mass of an element?
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What is the significance of the relative atomic mass of an element?
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How do you calculate the relative atomic mass of an element with multiple isotopes?
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Why do anions have a larger radius than their respective atoms?
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Why do cations have a smaller radius than their respective atoms?
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Using the periodic table, arrange the elements from smallest to largest in the set: C, F, Br, Ga.
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Why does the Ca2+ ion have a smaller radius than the calcium atom?
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Why does the O2- ion have a larger radius than the oxygen atom?
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Why is the chloride ion larger than the chlorine atom?
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Why is the sodium atom larger than the chlorine atom?
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What is the trend of ionisation energy across a period?
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Study Notes
Laboratory Safety
- In case of chemical spills, use safety showers to flush the affected area with plenty of water for 15 minutes to protect the eyes from further damage.
- Remove all contaminated clothing, jewelry, and shoes.
- Familiarize yourself with chemical hazard symbols to understand the safety aspects of any chemical being used.
Chemical Hazards and Safety Measures
- Be aware of the safety measures for hazardous substances, such as:
- Not placing flammable liquids near open flames and spark-producing equipment.
- Eliminating ignition sources when working with flammable and combustible liquids.
- Using the smallest amount of flammable liquid necessary in the work area.
- Keeping storage areas cool and dry.
- Storing flammable and combustible liquids away from incompatible materials.
Reflux
- Reflux is a laboratory technique used to heat a reaction mixture while preventing the loss of volatile compounds.
- The process involves boiling the reaction mixture, condensing the vapor, and returning it to the reaction vessel.
- Reflux is used to speed up chemical reactions, especially in organic chemistry, and to increase the yield of products.
Difference between Distillation and Reflux
- Reflux helps complete a reaction, while distillation separates components of a mixture.
- Reflux is used to heat a reaction mixture, while distillation is used to separate and purify substances.
Green Chemistry
- Green chemistry aims to make chemical processes more environmentally friendly.
- Three ways to make chemical processes "greener" are:
- Redesigning production methods to use different, less hazardous starting materials.
- Using milder reaction conditions, better catalysts, and less hazardous solvents.
- Using production methods with fewer steps and higher atom economy.
- Atom economy measures the amount of reactants that become useful products, with higher atom economy indicating "greener" processes.
Calculating Atom Economy
- Atom economy can be calculated using the formula: (Molecular weight of the desired product / Sum of the molecular weight of all substances produced) x 100.
Isotopes and Relative Atomic Mass
- Isotopes are atoms of the same element with different numbers of neutrons.
- Relative atomic mass is the weighted average of the atomic masses of the isotopes of an element.
- The relative atomic mass of an element can be calculated using the percentage abundance of each isotope.
Cations and Anions
- Cations are positively charged ions that are smaller than their respective atoms due to the stronger nuclear pull.
- Anions are negatively charged ions that are larger than their respective atoms due to the weaker nuclear pull and increased electron-electron repulsion.
Ionic Radius
- Ionic radius is the distance between the nucleus of an ion and its outermost electron.
- Cations have a smaller radius than their respective atoms, while anions have a larger radius than their respective atoms.
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Description
Learn how to properly use an emergency shower in a laboratory setting to flush away harmful chemicals and substances.