Chemistry A Study Of Matter 114 Answer Key

Chemistry A Study Of Matter 114 Answer Key Chemistry A Study of Matter Answer Key Grade 1112 This comprehensive answer key is designed to accompany the textbook Chemistry A Study of Matter for Grade 11 and 12 students It provides detailed solutions and explanations for all the exercises and problems found in the book enabling students to check their understanding and reinforce their learning Note This document provides a sample of answer keys for a few representative sections For complete coverage of all chapters and exercises please refer to the official answer key provided by the textbook publisher Chapter 1 to Chemistry Section 11 What is Chemistry Exercise 111 List five examples of how chemistry is used in everyday life Answer 1 Food preparation Cooking involves chemical reactions like oxidation browning of meat and chemical changes baking bread 2 Medicine Medications are designed using chemical principles to treat illnesses and alleviate pain 3 Cleaning Cleaning products use chemical reactions to break down dirt and grime 4 Agriculture Fertilizers and pesticides are developed based on chemical understanding of plant growth and pest control 5 Technology Electronics polymers and energy production rely heavily on chemical principles Exercise 112 Explain the difference between a pure substance and a mixture Answer Pure substance A substance composed of only one type of atom or molecule with a fixed composition and properties Examples water sugar gold Mixture A combination of two or more substances that are not chemically bonded 2 Components retain their individual properties and can be separated by physical means Examples salt and pepper air sand and water Chapter 2 Matter and Its Properties Section 22 Physical and Chemical Properties Exercise 221 Classify the following properties as physical or chemical Color Flammability Boiling point Reactivity with acid Density Answer Physical properties Color boiling point density These properties can be observed without changing the chemical composition of the substance Chemical properties Flammability reactivity with acid These properties describe how a substance reacts with other substances or under certain conditions leading to a change in its chemical composition Exercise 222 Explain the difference between a physical change and a chemical change Answer Physical change A change in the physical appearance of a substance without altering its chemical composition Examples melting ice dissolving sugar in water cutting paper Chemical change A change that results in the formation of new substances with different chemical compositions Examples burning wood rusting iron cooking an egg Chapter 3 Atomic Structure Section 31 The Atom Exercise 311 Describe the three main subatomic particles and their properties Answer Protons Positively charged particles located in the nucleus of the atom They determine the elements identity 3 Neutrons Neutrally charged particles located in the nucleus of the atom They contribute to the atoms mass Electrons Negatively charged particles orbiting the nucleus in specific energy levels called electron shells They participate in chemical bonding Exercise 312 What is the atomic number of an element How does it relate to the number of protons and electrons in a neutral atom Answer Atomic number The number of protons in the nucleus of an atom It defines the elements identity Relationship In a neutral atom the number of protons positive charge is equal to the number of electrons negative charge resulting in a balanced net charge Chapter 4 Periodic Table Section 42 Periodic Trends Exercise 421 Explain the trends in atomic radius ionization energy and electronegativity as you move across a period and down a group in the periodic table Answer Atomic radius Across a period Decreases The increasing number of protons in the nucleus attracts the electrons more strongly pulling them closer to the nucleus Down a group Increases The addition of electron shells pushes the outermost electrons further away from the nucleus Ionization energy Across a period Increases The stronger attraction between the nucleus and electrons makes it harder to remove an electron Down a group Decreases The outermost electrons are further from the nucleus experiencing weaker attraction and easier to remove Electronegativity Across a period Increases Atoms become more likely to attract electrons in a chemical bond due to increasing nuclear charge Down a group Decreases Atoms become less likely to attract electrons in a chemical bond 4 due to increased atomic size and shielding effects Chapter 5 Chemical Bonding Section 51 Ionic Bonding Exercise 511 Explain the formation of an ionic bond using the example of sodium chloride NaCl Answer Sodium Na has one valence electron and readily loses it to achieve a stable electron configuration Chlorine Cl has seven valence electrons and gains one electron to achieve a stable octet When sodium and chlorine react sodium loses its valence electron to chlorine forming a sodium ion Na and a chloride ion Cl The oppositely charged ions attract each other electrostatically forming an ionic bond in sodium chloride Exercise 512 Write the chemical formula for the ionic compound formed between magnesium Mg and oxygen O Answer MgO Chapter 6 Chemical Reactions Section 61 Types of Chemical Reactions Exercise 611 Identify the type of chemical reaction for each of the following equations A B C AB A B A BC AC B A B AB Answer A B C Synthesis reaction AB A B Decomposition reaction A BC AC B Single displacement reaction A B AB Combination reaction a specific type of synthesis reaction 5 Exercise 612 Write the balanced chemical equation for the combustion of methane CH4 in oxygen O2 Answer CH4 2O2 CO2 2H2O Chapter 7 Stoichiometry Section 71 Mole Concept Exercise 711 How many moles are present in 250 grams of sodium chloride NaCl Answer Molar mass of NaCl 5844 gmol Moles of NaCl 250 g 5844 gmol 0427 mol Exercise 712 Calculate the mass of 0750 moles of calcium carbonate CaCO3 Answer Molar mass of CaCO3 10009 gmol Mass of CaCO3 0750 mol 10009 gmol 7507 g Note This sample answer key provides a glimpse into the content and structure of the complete answer key for the textbook Chemistry A Study of Matter Remember to consult the official answer key for a thorough and comprehensive guide to all exercises and problems