Properties and Changes in Chemistry
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Questions and Answers

Which of the following describes a chemical property?

  • The boiling point of a substance.
  • Whether a substance will react with another substance. (correct)
  • The mass of a substance.
  • The colour of a substance.

    • Which of these observations is considered qualitative?

  • The volume of gas produced was 50 mL
  • The solution turned a shade of blue. (correct)
  • The temperature of the water increased by 10 degrees Celsius.
  • The mass of the precipitate was 12 grams.

    • What is the correct name for the ionic compound $FeSe$?

  • Iron selenide
  • Iron(I) selenide
  • Iron monoselenide
  • Iron(II) selenide (correct)

    • What is the correct formula for the compound formed between Magnesium and the polyatomic ion hydroxide?

    <p>$Mg(OH)_2$</p> Signup and view all the answers

    What would the name of $H_3PO_4$ be, based on the naming rules for acids?

    <p>Phosphoric acid</p> Signup and view all the answers

    Which of the following is an example of a hydrate?

    <p>$CuSO_4 \cdot 5H_2O$</p> Signup and view all the answers

    In an atom, where is the majority of mass concentrated?

    <p>In the nucleus.</p> Signup and view all the answers

    Which of the following is an example of extensive physical property?

    <p>Volume</p> Signup and view all the answers

    What type of chemical reaction is represented by the general equation $A + BC \rightarrow AC + B$?

    <p>Single replacement</p> Signup and view all the answers

    In a balanced chemical equation, which numbers are adjusted to ensure the same number of atoms on both sides of the equation?

    <p>Coefficients</p> Signup and view all the answers

    In an exothermic reaction, how does the energy stored in the products compare to the energy stored in the reactants?

    <p>The energy in the products is less than the reactants.</p> Signup and view all the answers

    What is the enthalpy change ($\Delta H$) for an endothermic reaction?

    <p>Positive</p> Signup and view all the answers

    Which of the following must be converted to moles before conducting stoichiometric calculations?

    <p>All of the above</p> Signup and view all the answers

    Which term describes the reactant that is completely consumed during a chemical reaction?

    <p>Limiting reactant</p> Signup and view all the answers

    How is percent yield calculated in a chemical reaction?

    <p>Experimental yield / Theoretical yield * 100%</p> Signup and view all the answers

    If a solution has a pH of 5, how many times less acidic is it than a solution with a pH of 2?

    <p>1000</p> Signup and view all the answers

    If a reaction's percent yield is greater than 100%, what is a likely cause?

    <p>The final product was not completely dry</p> Signup and view all the answers

    What is a key difference between ionic and molecular solutions in water?

    <p>Ionic solutions break apart into ions, allowing them to conduct electricity and molecular solutions do not</p> Signup and view all the answers

    Which of the following is NOT a necessary piece of data to record during a titration?

    <p>The temperature of the reactants</p> Signup and view all the answers

    Which of the following describes a substance that does not dissolve easily in water, and may form a precipitate?

    <p>Low soluble compound</p> Signup and view all the answers

    When should a trial be rejected during a titration experiment?

    <p>If the difference between a trial is more than double the other difference.</p> Signup and view all the answers

    Which of the following is considered a polar solvent?

    <p>Water</p> Signup and view all the answers

    What is represented in a net ionic equation?

    <p>Only ions that undergo a reaction</p> Signup and view all the answers

    According to the Arrhenius theory, what ion do acids release in water?

    <p>Hydrogen ($H^+$) or Hydronium ($H_3O^+$)</p> Signup and view all the answers

    What type of substances dissolve best in non-polar solvents?

    <p>Non-polar substances</p> Signup and view all the answers

    Which of following is NOT a characteristic of a base from Arhenius theory?

    <p>Turns blue litmus paper red</p> Signup and view all the answers

    What is the primary focus of organic chemistry?

    <p>The study of carbon-based molecules</p> Signup and view all the answers

    What does a lower pH value indicate on the pH scale?

    <p>More acidic</p> Signup and view all the answers

    How many bonds can a carbon atom form?

    <p>4</p> Signup and view all the answers

    What suffix do all alkanes end with?

    <p>-ane</p> Signup and view all the answers

    What is the pH of a neutral solution at room temperature?

    <p>7</p> Signup and view all the answers

    If you had substituent groups containing a Bromine and a Chlorine, how would the names be written?

    <p>Bromo, then Chloro</p> Signup and view all the answers

    What are organic compounds with the same formula but different structures called?

    <p>Isomers</p> Signup and view all the answers

    Which best describes structural isomers?

    <p>Same chemical formula, different connections between atoms</p> Signup and view all the answers

    What is the primary goal of 'atom economy' in green chemistry?

    <p>To minimize waste by using as many atoms as possible in a reaction</p> Signup and view all the answers

    Which of the following is an example of 'design for energy efficiency' in green chemistry?

    <p>Using reactions at room temperature and neutral pressure.</p> Signup and view all the answers

    How does catalysis contribute to green chemistry?

    <p>By improving the efficiency and effectiveness of reactions</p> Signup and view all the answers

    Which of the following best describes the relationship between atomic number and the periodic table?

    <p>The periodic table is arranged by increasing atomic number.</p> Signup and view all the answers

    What does the principle of 'design for degradation' aim to achieve in green chemistry?

    <p>To make chemicals break down in the environment after use</p> Signup and view all the answers

    What is the mass of an atom with 15 protons, 16 neutrons, and 15 electrons?

    <p>31 amu</p> Signup and view all the answers

    What do isotopes of an element always have in common?

    <p>The same number of protons.</p> Signup and view all the answers

    Which of the following electron configurations is correct for a neutral vanadium (V) atom, which has 23 electrons?

    <p>1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³</p> Signup and view all the answers

    What is the correct electron configuration for the N³⁻ ion?

    <p>1s² 2s² 2p⁶</p> Signup and view all the answers

    Which subshells are considered to be the valence shell in most cases?

    <p>s and p orbitals</p> Signup and view all the answers

    According to the octet rule, most atoms are most stable when they have how many electrons in their valence shell?

    <p>8</p> Signup and view all the answers

    What type of bond is formed when electrons are shared equally between two atoms?

    <p>True Covalent Bond</p> Signup and view all the answers

    Which of these intermolecular forces is the strongest?

    <p>Hydrogen Bonding</p> Signup and view all the answers

    Which of the following is NOT a shape that can be associated with polar molecules?

    <p>Linear</p> Signup and view all the answers

    How does electronegativity difference affect the type of chemical bond formed?

    <p>Large electronegativity differences lead to ionic bonds.</p> Signup and view all the answers

    What causes London dispersion forces?

    <p>Fluctuations in electron density</p> Signup and view all the answers

    What is the correct electron configuration for Mn²⁺ ion?

    <p>[Ar] 4s⁰ 3d⁵</p> Signup and view all the answers

    Which of the following elements is an exception to the typical filling order of electron orbitals?

    <p>Chromium</p> Signup and view all the answers

    What is the formula for calculating the number of bonds an atom will form?

    <p>(# electrons wanted - #electrons present)/2</p> Signup and view all the answers

    Which of the following correctly describes the relationship between intermolecular forces and the state of a substance at a given temperature?

    <p>Stronger intermolecular forces favor the liquid or solid state.</p> Signup and view all the answers

    If a measurement is taken and the reading falls directly on a marked line on a ruler, how should it be recorded?

    <p>Record the value to the line and add a trailing '0'.</p> Signup and view all the answers

    A student performs a calculation involving measurements. The original measurements have 3 and 4 significant figures, respectively. According to significant figure rules, how many significant figures should the answer have IF the operation was multiplication?

    <p>3</p> Signup and view all the answers

    What is the correct scientific notation for 0.0006070?

    <p>$6.070 \times 10^{-4}$</p> Signup and view all the answers

    Which of the following is considered an intensive property?

    <p>Density</p> Signup and view all the answers

    In a graph examining the relationship between the mass and volume of a substance, what does the slope of the line of best fit represent?

    <p>The density of the substance.</p> Signup and view all the answers

    How many molecules are present in 2.5 moles of a substance?

    <p>$1.505 \times 10^{24}$ molecules</p> Signup and view all the answers

    How many atoms of oxygen are present in 0.25 moles of $O_2$?

    <p>$0.50 \times 6.02 \times 10^{23}$ atoms</p> Signup and view all the answers

    What is the molar mass of $H_2SO_4$?

    <p>98 g/mol</p> Signup and view all the answers

    What volume does 2 moles of an ideal gas occupy at STP?

    <p>44.8 L</p> Signup and view all the answers

    How many moles of $CH_2O$ are present in 60g of $CH_2O$? (Molar mass of $CH_2O = 30 g/mol$)

    <p>2 mol</p> Signup and view all the answers

    What is the mass of 0.5 moles of NaCl? (Molar mass of NaCl = 58.5 g/mol)

    <p>29.25 g</p> Signup and view all the answers

    What is the concentration, in molarity, of a solution containing 0.5 moles of solute in 500 mL of solution?

    <p>1.0 M</p> Signup and view all the answers

    Which of the following is an example of a synthesis reaction?

    <p>$H_2 + Cl_2 \rightarrow 2HCl$</p> Signup and view all the answers

    Which one of these is a base unit in the metric system?

    <p>grams</p> Signup and view all the answers

    Study Notes

    Properties, Changes, and Observations

    • Physical change: A change in form or shape, but not chemical makeup.
    • Chemical change: A change where a new substance or molecule forms. Indicators include color change, bubble formation, temperature change, combustion.
    • Physical property: A feature describing how a substance exists at a given temperature (e.g., color, texture).
    • Chemical property: A feature describing how a substance reacts (e.g., flammability, reactivity with acids).
    • Intensive property: A property that remains consistent regardless of the amount of substance.
    • Extensive property: A property that changes with the amount of substance.
    • Observation: The basis of science; noting and recording what is seen, heard, smelled, felt, or tasted. Focus on what happens, not why.
    • Qualitative observation: Descriptive (color, feel, size).
    • Quantitative observation: Based on numbers.

    Naming and Formulas for Ionic Compounds

    • Ionic compound formulas: Determine charges of ions, then balance the charges. Example: Li₂O, FeSe, Mg(OH)₂
    • Ionic compound names: Name the cation first, indicate oxidation state if multivalent, then name the anion. If the anion is a polyatomic ion, do not change the ending. If the anion is a single element, change the ending to "-ide."

    Acids

    • Acids: Compounds releasing hydrogen ions (H⁺) in solution (aqueous state).
    • Acid formulas: Often start with "H" or end in "COOH."
    • Acid naming (no oxygen): Hydro- + root name + -ic acid (e.g., H₂S – hydrosulfuric acid)
    • Acid naming (with oxygens): Root name of polyatomic ion, "-ate" ending becomes "-ic acid," "-ite" ending becomes "-ous acid" (e.g., H₂SO₄ – sulfuric acid, H₂SO₃ – sulfurous acid).

    Hydrates

    • Hydrates: Compounds trapping water in their crystal structure (e.g., NiCl₂ • 2H₂O – Nickel(II) chloride dihydrate).

    Atoms

    • Atom: Tiny piece of matter, comprising a nucleus and electron cloud.
    • Nucleus: Dense center containing protons and neutrons.
    • Proton: Particle with +1 charge and 1 amu mass, determining the element.
    • Neutron: Particle with neutral charge and 1 amu mass.
    • Electron cloud: Space where electrons are found, virtually no mass, -1 charge.
    • Atomic number: Number of protons.
    • Atomic mass/mass number: Number of protons + neutrons (whole number).
    • Neutral atom: Protons = electrons.
    • Ion: Charged particle, electron loss or gain.
    • Isotope: Atoms of same element, different number of neutrons.
    • Atomic Orbital: Spaces around an atom where electrons are likely to be found.

    Electron Configurations

    • Electron configurations: Electrons fill orbitals from lowest to highest energy levels.
    • Degenerate orbitals: Orbitals with the same energy.
    • Shell Filling Order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p ...
    • Electron configuration notation: Shows which subshells contain electrons (e.g., Carbon: 1s²2s²2p²).
    • Core notation: Using noble gas symbol to represent inner electrons (e.g., Manganese: [Ar] 4s²3d⁵).

    Ions

    • Valence electrons are removed/added first, then s electrons, then d electrons for positive ions.
    • Negative ions add electrons. This changes their electron configuration.

    Bonds

    • Covalent bonds: Electrons shared between atoms.
    • Polar covalent bonds: Unequal sharing of electrons due to electronegativity differences.
    • Ionic bonds: Complete transfer of electrons.
    • Electronegativity: Ability to attract electrons.

    Molecular Forces

    • Intermolecular forces: Forces holding molecules together in liquids and solids.
    • Dipole-dipole forces: Attraction between polar molecules.
    • Hydrogen bonding: Special dipole-dipole force in molecules with H-O, H-N, or H-F bonds.
    • London dispersion forces: Temporary dipoles in all molecules due to electron cloud fluctuations.

    Measurement and Significant Figures

    • Measurement Uncertainty: All measurements have some degree of uncertainty; estimate the last digit reported.
    • Significant Figures: Indicate how well a number is known. Rules for determining significant figures

    Moles

    • Mole: Unit for counting atoms/molecules (Avogadro's number = 6.02 x 10²³).
    • Molar mass: Mass of 1 mole of a substance, found on the periodic table.
    • Molar mass conversion: Use for converting between moles and grams.
    • Molar volume (STP): 22.4 L/mol for any gas at standard temperature and pressure (STP).

    Solution Concentration

    • Concentration: Amount of solute per unit volume (e.g., molarity = moles/liter).
    • Dilution: Changing the concentration of a solution by adding more solvent.

    Chemical Reactions

    • Chemical Reactions: Breaking and forming of bonds, changing chemical potential energy.
    • Reaction Types: Synthesis, decomposition, single replacement, double replacement, neutralization, combustion.
    • Chemical Equations: Balancing equations to maintain atom conservation.
    • Exothermic reaction: Energy released as a product (enthalpy is Negative).
    • Endothermic reaction: Energy absorbed as a reactant (enthalpy is Positive).
    • Stoichiometry: Using balanced equations to calculate reactant/product ratios.
    • Limiting Reactant: Reactant used up first, controls product yield.
    • Percent Yield: Comparing actual yield to theoretical yield.

    Solution Properties

    • Aqueous Solutions: Substances dissolved in water.
    • Ionic Solutions: Dissolve into separate ions and conduct electricity.
    • Molecular Solutions: Do not form ions, do not conduct electricity easily.
    • Solubility: Ability of a substance to dissolve in a solvent.
    • Precipitate: Insoluble solid formed in a reaction of different aqueous solutions.

    pH and Titration

    • pH Scale: Logarithmic scale measuring acidity (0-14). Lower pH means more acidic.
    • Titration: Analytical technique to precisely determine the concentration of a solution.

    Organic Chemistry

    • Organic Chemistry: Study of carbon-based molecules.
    • Alkanes: Carbon chains with single bonds.
    • Substituent groups: Groups attached to the main carbon chain.
    • Isomers: Molecules with the same formula, different structures. (structural, geometric, optical isomers)
    • Alkenes: Carbon chains with at least one double bond.

    Green Chemistry Principles

    • Waste Prevention: Minimize waste generation.
    • Atom Economy: Maximize use of atoms in the reaction.
    • Less Hazardous Chemical Synthesis: Use less hazardous reagents.
    • Safer Chemicals Design: Design less toxic chemicals.
    • Safe Solvents and Auxiliaries: Use less hazardous solvents.
    • Energy Efficiency: Minimize energy consumption.

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    Test your knowledge on the properties, changes, and observations relating to physical and chemical substances. Explore intensive and extensive properties, as well as how to distinguish between qualitative and quantitative observations. Take this quiz to solidify your understanding of these fundamental concepts in chemistry.

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