College Entrance Exam Tips and Chemistry Pointers
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Questions and Answers

What is the study of chemicals containing the element carbon?

  • Organic Chemistry (correct)
  • Inorganic Chemistry
  • Physical Chemistry
  • Analytical Chemistry

    • Plasma is sometimes referred to as the fourth state of matter.

    True

    Define a compound.

    A compound is a substance in which two or more elements are joined by chemical bonds.

    An atom is the smallest unit of an element that has the properties of the element; a molecule is the smallest unit of a compound or the form of an element in which atoms bind together that has the properties of the compound or element.

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

    Match the following sub-atomic particles with their descriptions:

    <p>Nucleus = Contains most of the atomic mass Electrons = Negatively charged particles Proton = Carries a positive electric charge Neutron = No electric charge</p> Signup and view all the answers

    What law, proposed by Dalton, states that in every compound, the proportion by weight of each element may be expressed by the atomic weight or a multiple of the atomic weight of each element?

    <p>The law of combining weights</p> Signup and view all the answers

    What does stoichiometry deal with?

    <p>Quantitative relationships between reactants and products of a chemical reaction</p> Signup and view all the answers

    For every 2 moles of butane, how many moles of water will be produced according to the reaction: 2CH4H______ + 13O2 --> 8 CO2 + ______H20?

    <p>10</p> Signup and view all the answers

    If 0.25 moles of sodium carbonate is heated, what mass of sodium oxide will be produced?

    <p>15.50 grams</p> Signup and view all the answers

    Balancing a chemical equation requires the same number of atoms for each element on both sides.

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

    What does Boyle's Law state?

    <p>The volume of a certain amount of dry gas held at constant temperature is inversely proportional to the pressure exerted by the gas.</p> Signup and view all the answers

    What is Charles' Law?

    <p>The volume of a certain amount of dry gas at constant pressure is directly proportional to its absolute temperature.</p> Signup and view all the answers

    State Avogadro's Law.

    <p>At a given temperature and pressure, the same volume of any two gases contain an equal number of molecules.</p> Signup and view all the answers

    What is the Ideal Gas Law equation?

    <p>PV = nRT</p> Signup and view all the answers

    What law is expressed as Pt = P1 + P2 + P3 + .... + Pn?

    <p>Dalton's Law of Partial Pressure</p> Signup and view all the answers

    What is the relationship between the rate of effusion of a gas and its molecular weight, according to Graham's Law?

    <p>Inversely proportional</p> Signup and view all the answers

    What are monosaccharides made of?

    <p>One simple sugar unit</p> Signup and view all the answers

    What are disaccharides made up of?

    <p>Two simple sugar units</p> Signup and view all the answers

    What are polysaccharides made of?

    <p>More than two simple sugar units</p> Signup and view all the answers

    What is the main objective of the Academic-Clinic website?

    <p>Providing college entrance exam tips</p> Signup and view all the answers

    In an ionic bond, electrons are shared between atoms.

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

    How many common amino acids are found in the body?

    <p>About 20</p> Signup and view all the answers

    What type of bonding occurs when atoms share outer electrons?

    <p>covalent bonds</p> Signup and view all the answers

    RNA uses thymine as one of its bases.

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

    What is responsible for the replication of DNA?

    <p>Double-helix structure</p> Signup and view all the answers

    ______ can be expressed through equations that resemble mathematical equations.

    <p>chemical reactions</p> Signup and view all the answers

    Match the following nucleic acid sugars with the type of nucleic acid they form:

    <p>Ribose = RNA Deoxyribose = DNA</p> Signup and view all the answers

    Match the following types of chemical reactions with their descriptions:

    <p>Composition Reaction = A type of reaction where a complex substance breaks down into simpler substances Decomposition Reaction = A type of reaction where a complex substance breaks down into simpler substances Single Replacement Reaction = A type of reaction where a less reactive element is displaced by a more reactive element Double Displacement Reaction = A type of reaction where cations of two compounds switch anions to form new products</p> Signup and view all the answers

    Calculate the mole fraction of the Ca(OH)2 in the solution.

    <p>0.17</p> Signup and view all the answers

    What is the molarity of the solution with 45g of sodium hydroxide in 200 cc of solution?

    <p>5.6 molar</p> Signup and view all the answers

    Find the molality of a solution containing 35g of ammonia in 500g of water.

    <p>4.1 molal</p> Signup and view all the answers

    Calculate the normality of a 1.5L solution containing 18.3g of sulfuric acid.

    <p>0.25 normal</p> Signup and view all the answers

    What is the classification of acids that yield OH- ions in aqueous solutions?

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

    Describe the taste of bases.

    <p>Bitter taste</p> Signup and view all the answers

    What is the pH range for acids?

    <p>pH &lt; 7</p> Signup and view all the answers

    Explain the difference between alkanes and alkenes in hydrocarbons.

    <p>Alkanes have only single bonds, while alkenes have at least one carbon-to-carbon double bond.</p> Signup and view all the answers

    What type of hydrocarbons contain cyclical hydrocarbon rings with all atoms sp2 hybridized?

    <p>Aromatic compounds</p> Signup and view all the answers

    What are the two components of a solution?

    <p>Solute and solvent</p> Signup and view all the answers

    What is the measure of the quantity of a solute in a given amount of solution or solvent?

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

    Solubility is the measure of the amount of solute that can be dissolved in a given quantity of ________ at a specific temperature.

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

    The solubility of gases in water increases with temperature.

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

    Match the following factors with their effects on the rate of dissolution:

    <p>Size of particles = Faster dissolution Rate of stirring = Increased contact between solute and solvent Heating = Increased kinetic energy</p> Signup and view all the answers

    What is the formula for percent concentration by mass (Pm)?

    <p>Mass of solute / total mass of solution x 100%</p> Signup and view all the answers

    Calculate the percent by mass of hydrogen chloride in the cleanser.

    <p>33%</p> Signup and view all the answers

    How much water must be added to 50 grams of salt to prepare a 50% solution?

    <p>50 grams</p> Signup and view all the answers

    Calculate the concentration of benzene in percent by volume.

    <p>30%</p> Signup and view all the answers

    Determine the volume of the 0.84% sodium chloride solution to be administered if 208 grams of sodium chloride are used.

    <p>322 mL</p> Signup and view all the answers

    What is the formula for mole fraction?

    <p>Mole of solute / Mole solution</p> Signup and view all the answers

    Calculate the mole fraction of calcium hydroxide in water.

    <p>0.45</p> Signup and view all the answers

    Study Notes

    Chemistry Basics

    • Chemistry is the physical science that deals with the composition, structure, and properties of substances and their transformations.
    • It is central to the understanding of other sciences.

    Branches of Chemistry

    • Organic chemistry: concerned with the study of chemicals containing the element carbon.
    • Inorganic chemistry: the study of all elements of compounds other than organic compounds.
    • Analytical chemistry: the study of qualitative and quantitative analysis of elements and compounds.
    • Physical chemistry: the study of reaction rates, mechanisms, bonding, and structure.

    Matter

    • Matter is a general term applied to anything that has the property of occupying space and the attributes of gravity and inertia.
    • States of matter: plasma, solid, liquid, and gas.

    Physical and Chemical Changes

    • Physical change: characterized by a change in the phase or state of a substance, with no change in its chemical composition.
    • Chemical change: characterized by a change in the composition of molecules, with new substances produced.

    Phase Changes

    • Phase transition: a change in the state of matter caused by a change in temperature and/or pressure.
    • Examples: solid to liquid, liquid to gas, etc.

    Elements and Compounds

    • Element: a substance that cannot be broken down into simpler substances by ordinary means.
    • Compound: a substance made up of two or more elements joined by chemical bonds.

    Atoms and Molecules

    • Atom: the smallest unit of an element with the properties of the element.
    • Molecule: the smallest unit of a compound or an element in which atoms bind together.

    Subatomic Particles

    • Nucleus: the central part of an atom, contains most of the atomic mass.
    • Electrons: small, negatively charged particles that orbit the nucleus.
    • Protons: positively charged particles in the nucleus.
    • Neutrons: particles with no electric charge in the nucleus.

    Atomic Number and Mass Number

    • Atomic number: the number of protons in an atom's nucleus.
    • Mass number: the total number of protons and neutrons in an atom's nucleus.

    Isotopes

    • Isotopes: atoms of the same element with the same number of protons but different numbers of neutrons.

    Atomic Weight

    • Atomic weight: the average weight of an atom of an element, taking into account the masses of all its isotopes.

    Models of the Atom

    • An atom of an element is denoted by aXb, where X is the nucleus, a is the mass number, and b is the atomic number.

    Electron Configuration

    • Electron configuration: the arrangement of an atom's electrons with respect to its nucleus.
    • Valence electrons: electrons in the highest energy level of the electron cloud.

    Chemical Bonds

    • Ionic bonds: formed when electrons are transferred from one atom to another to achieve noble gas configuration.
    • Covalent bonds: formed when sharing of available outer electrons of the atoms occurs.

    Chemical Reactions

    • Chemical reactions: involve the breakage and reformation of chemical bonds to form different substances.
    • Types of chemical reactions: composition, decomposition, single replacement, and double displacement reactions.

    Types of Chemical Reactions

    • Composition reaction: a reaction in which a more complex substance is formed from simpler substances.
    • Decomposition reaction: a reaction in which a more complex substance is broken down into simpler substances.
    • Single replacement reaction: a reaction in which a less reactive element is displaced from a compound by a more reactive element.
    • Double displacement reaction: a reaction in which cations of two compounds switch anions to form new products.

    Exothermic and Endothermic Reactions

    • Exothermic reaction: a chemical reaction that releases energy.

    • Endothermic reaction: a chemical reaction that absorbs energy.### Photosynthesis

    • Photosynthesis requires light from the sun to proceed and is an example of an endothermic reaction.

    Factors Affecting the Rate of a Chemical Reaction

    • The rate of a chemical reaction is affected by several factors:
      • Nature of the reactants: the more reactive the reactants, the faster the reaction.
      • Temperature: generally, the higher the temperature, the faster the reaction.
      • Concentration of the reactants: the higher the concentration, the faster the reaction.
      • Surface area: the smaller the surface area, the faster the reaction.
      • Effect of a catalyst: the presence of a catalyst makes the reaction faster.

    Laws of Chemical Combination

    • The laws of chemical combination were formulated in the early 19th century and are based on quantitative measurements in chemistry.
    • The laws include:
      • Law of Definite Proportions (also called the Law of Constant Composition): compounds contain elements in certain fixed proportions, regardless of the method of preparation.
      • Law of Multiple Proportions: if two elements combine to form more than one compound, the ratio of the weights of the second element will be small whole numbers.
      • Law of Combining Weights: in every compound, the proportion by weight of each element can be expressed by the atomic weight or a multiple of the atomic weight of each element.

    Balancing Equations

    • The numbers of atoms for each element should be equal on the reactant and product sides of a chemical equation.
    • A chemical equation is considered balanced if there are exactly the same number of atoms for each element on both sides of the equation.

    Stoichiometry

    • Stoichiometry is the branch of chemistry that deals with quantitative relationships between the reactants and products of a chemical reaction.
    • Examples of stoichiometry include:
      • Mole to Mole: calculating the amount of product formed based on the amount of reactant used.
      • Mole to Mass: calculating the mass of product formed based on the amount of reactant used.
      • Mass to Mass: calculating the mass of product formed based on the mass of reactant used.
      • Mass to Mole: calculating the amount of product formed based on the mass of reactant used.

    Kinetic Molecular Theory

    • The kinetic molecular theory is a model that explains the behavior of gases.
    • The postulates of the kinetic molecular theory are:
      • Gases are made up of very tiny particles, called molecules, with big empty spaces between them.
      • Gaseous molecules are in constant random motion.
      • The intermolecular forces of attraction between gaseous particles are very weak.
      • The collision of gas particles with each other or with the walls of its container is perfectly elastic.
      • The average kinetic energy of the gas particles is directly proportional to the absolute temperature.

    The Gas Laws

    • The gas laws are a set of laws that govern the behavior of gases.
    • Examples of the gas laws include:
      • Boyle's Law: the volume of a gas is inversely proportional to the pressure exerted by the gas, at constant temperature.
      • Charles' Law: the volume of a gas is directly proportional to its absolute temperature, at constant pressure.### Combined Gas Laws
    • The combined gas law states that P1V1 = P2V2 / T1T2
    • It is used to relate the initial and final conditions of a gas
    • The law is derived from Boyle's Law, Charles' Law, and Avogadro's Law

    Ideal Gas Law

    • The ideal gas law states that PV = nRT
    • It relates the pressure, volume, and temperature of an ideal gas
    • The universal gas constant, R, is equal to 0.0821 atm-L/molK

    Avogadro's Law

    • Avogadro's Law states that at a given temperature and pressure, the same volume of any two gases contain equal numbers of molecules
    • The molar volume of any gas at STP is 22.4 L

    Graham's Law

    • Graham's Law states that the rate of effusion of a gas is inversely proportional to the square root of its molecular weight
    • Heavier gases have a slower rate of effusion

    Dalton's Law of Partial Pressure

    • Dalton's Law states that the pressure exerted by a mixture of non-reacting gases is the sum of the partial pressures of each gas
    • The law is expressed mathematically as Pt = P1 + P2 + ... + Pn

    Solutions

    • A solution is a homogeneous mixture of two or more substances whose components are uniformly distributed
    • Solutions have two components: a solute and a solvent
    • The concentration of a solution is the measure of the quantity of solute in a given amount of solution or solvent

    Factors Affecting the Rate of Dissolution

    • Size of particles: smaller particles have a faster rate of dissolution
    • Rate of stirring: stirring increases the rate of dissolution
    • Heating: heating increases the kinetic energy of the system and the rate of dissolution

    Modes of Expressing Concentration

    • Percent concentration: the ratio of the amount of solute to the total amount of solution, expressed as a percentage
    • Percent by mass: the ratio of the mass of solute to the total mass of solution, expressed as a percentage
    • Percent by volume: the ratio of the volume of solute to the total volume of solution, expressed as a percentage
    • Mole fraction: the ratio of the number of moles of solute to the total number of moles of solution

    Applications of Concentration

    • Preparing a ceramic tile cleanser: calculating the percent by mass of hydrogen chloride in the cleanser
    • Preparing a solution: calculating the amount of water needed to prepare a solution of a given concentration
    • Administering a medication: calculating the volume of a solution needed to administer a certain amount of medication

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