Introduction to Chemistry
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Questions and Answers

Which branch of chemistry is most directly concerned with the study of the elemental composition of a newly discovered mineral?

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

A chemist is tasked with synthesizing a new polymer. Which branch of chemistry would be most applicable to this project?

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

Consider a container filled with a substance that has a definite volume but adapts to the shape of the container. What is the state of matter of this substance?

  • Solid
  • Liquid (correct)
  • Gas
  • Plasma

Which of the following properties is an example of an intensive property of matter?

<p>Density (B)</p> Signup and view all the answers

Burning wood is an example of what type of change?

<p>Chemical Change (C)</p> Signup and view all the answers

An atom has 17 protons and 18 neutrons. What is its mass number?

<p>35 (C)</p> Signup and view all the answers

What distinguishes an ion from its corresponding neutral atom?

<p>Different number of electrons (C)</p> Signup and view all the answers

Which type of chemical bond involves the sharing of electrons between atoms?

<p>Covalent Bond (D)</p> Signup and view all the answers

Which of the following best describes the nature of electron behavior in a metallic bond?

<p>Electrons are delocalized and move freely throughout the metal lattice. (C)</p> Signup and view all the answers

In a chemical reaction, 2A + B -> C, if the molar mass of A is 20 g/mol and B is 10 g/mol, How many grams of A are needed to completely react with 5 grams of B?

<p>20 grams (B)</p> Signup and view all the answers

Consider the reaction: $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$. If, at equilibrium, the concentration of $N_2$ is 2M, $H_2$ is 3M, and $NH_3$ is 4M, what is the equilibrium constant, K?

<p>K = 0.74 (D)</p> Signup and view all the answers

Which of the following is true regarding the relationship between the actual yield and the theoretical yield in a chemical reaction?

<p>The actual yield is usually less than the theoretical yield. (C)</p> Signup and view all the answers

Hydrochloric acid (HCl) is added to a solution of sodium hydroxide (NaOH). Which of the following will occur?

<p>The pH of the solution will decrease, becoming more acidic. (B)</p> Signup and view all the answers

Which of the following changes will likely increase the rate of a chemical reaction?

<p>Adding a catalyst to the reaction. (C)</p> Signup and view all the answers

Consider a reversible reaction at equilibrium: $A \rightleftharpoons B$. If the equilibrium constant K is much greater than 1, what does this indicate about the reaction?

<p>The reaction strongly favors the products. (D)</p> Signup and view all the answers

Which of the following is a direct measure of the spontaneity of a chemical reaction under constant pressure and temperature?

<p>Gibbs Free Energy (G) (A)</p> Signup and view all the answers

In an electrochemical cell, at which electrode does oxidation occur?

<p>Anode (A)</p> Signup and view all the answers

What is the molarity of a solution containing 40 grams of NaOH in 500 mL of solution? (Molar mass of NaOH = 40 g/mol)

<p>2.0 M (C)</p> Signup and view all the answers

Flashcards

What is chemistry?

The study of matter, its properties, and how it changes.

What is matter?

Anything that has mass and takes up space.

What are intensive properties?

Properties that do not change with the amount of substance.

What are extensive properties?

Properties that depend on the amount of substance.

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What is a physical change?

Alters the form of a substance without changing its chemical identity.

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What is a chemical change?

Rearrangement of atoms to form new substances.

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What are protons?

Positively charged particles in the nucleus of an atom.

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What are isotopes?

Atoms of the same element with different numbers of neutrons.

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Metallic Bond

Force of attraction between delocalized electrons and metal ions.

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Reactants

Substances that are changed in a chemical reaction.

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Chemical Equation

Symbolic representation of a chemical reaction.

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6.022 x 10^23

Avogadro's Number

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Limiting Reactant

Reactant that limits the amount of product formed.

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Molarity (M)

Moles of solute per liter of solution.

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Acids

Substances that donate protons or accept electrons.

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Catalysts

Substances that speed up reactions without being consumed.

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Equilibrium Constant

Ratio of products to reactants at equilibrium.

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Anode

Electrode where oxidation occurs.

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Study Notes

  • Chemistry is the study of matter, its properties, and how it changes.
  • Matter is anything that has mass and occupies space.

Branches of Chemistry

  • Analytical Chemistry focuses on the composition of matter.
  • Biochemistry studies chemical processes within living organisms.
  • Inorganic Chemistry studies substances lacking carbon.
  • Organic Chemistry studies carbon-containing substances.
  • Physical Chemistry studies the physics of chemical systems.

States of Matter

  • Solids have definite shape and volume.
  • Liquids have a definite volume but take the shape of their container.
  • Gases lack definite shape or volume.
  • Plasma comprises ionized gas at high temperatures.

Properties of Matter

  • Intensive properties do not depend on the amount of matter (e.g., density, color).
  • Extensive properties depend on the amount of matter (e.g., mass, volume).
  • Physical properties are observed without changing the substance's composition (e.g., boiling point, melting point).
  • Chemical properties describe how a substance changes into a new one (e.g., flammability, reactivity).

Changes of Matter

  • Physical changes alter the form without changing chemical identity (e.g., melting, boiling).
  • Chemical changes rearrange atoms to form new substances (e.g., combustion, oxidation).

Atoms

  • Atoms are the basic building blocks of matter.
  • Atoms consist of protons, neutrons, and electrons.
  • Protons are positively charged particles in the nucleus.
  • Neutrons are neutral particles in the nucleus.
  • Electrons are negatively charged particles orbiting the nucleus.
  • Atomic number is the number of protons in an atom.
  • Mass number is the total number of protons and neutrons in an atom.
  • Isotopes are atoms of the same element with different neutron numbers.

Molecules and Compounds

  • Molecules consist of two or more atoms held by chemical bonds.
  • Compounds are substances of two or more different elements chemically combined.
  • Molecular formulas show the exact number of each element's atoms in a molecule.
  • Empirical formulas show the simplest whole-number ratio of atoms in a compound.

Ions

  • Ions are atoms or molecules that have gained or lost electrons.
  • Cations are positively charged ions (lost electrons).
  • Anions are negatively charged ions (gained electrons).
  • Ionic compounds are formed through ionic bonds between ions.

Chemical Bonds

  • Ionic bonds form through the transfer of electrons between atoms.
  • Covalent bonds form through the sharing of electrons between atoms.
  • Metallic bonds are found in metals, where electrons are delocalized among a lattice of atoms.

Chemical Reactions

  • Reactions rearrange atoms and molecules to form new substances.
  • Reactants are substances undergoing change.
  • Products are substances being formed.
  • Chemical equations are symbolic representations of chemical reactions.
  • Balancing equations ensures the same number of atoms for each element on both sides.

Mole Concept

  • A mole is a substance amount containing the same number of entities as atoms in exactly 12 grams of carbon-12.
  • Avogadro's Number is 6.022 x 10^23, representing the number of entities in one mole.
  • Molar mass is the mass of one mole of a substance.

Stoichiometry

  • Stoichiometry involves the quantitative study of reactants and products in a reaction.
  • Balanced chemical equations are used to determine the amounts of reactants and products.
  • The limiting reactant is completely consumed in a reaction.
  • Theoretical yield is the maximum product amount from the limiting reactant.
  • Actual yield is the obtained product amount from a reaction.
  • Percent yield is calculated as (Actual Yield / Theoretical Yield) x 100%.

Solutions

  • Solutions are homogeneous mixtures of two or more substances.
  • The solvent is present in the larger amount.
  • The solute is present in the smaller amount.
  • Concentration is the solute amount in a given amount of solvent or solution.
  • Molarity (M) is moles of solute per liter of solution.
  • Molality (m) is moles of solute per kilogram of solvent.

Acids and Bases

  • Acids donate protons (H+) or accept electrons.
  • Bases accept protons (H+) or donate electrons.
  • The pH scale measures acidity or basicity (0-14).
  • Acidic solutions have a pH < 7.
  • Neutral solutions have a pH = 7.
  • Basic solutions have a pH > 7.
  • Strong acids/bases completely dissociate in water.
  • Weak acids/bases partially dissociate in water.
  • Neutralization is the reaction between an acid and a base, forming a salt and water.

Chemical Kinetics

  • Chemical kinetics studies reaction rates and influencing factors.
  • Reaction rate involves the change in reactant or product concentration per unit time.
  • Factors affecting reaction rate include temperature, concentration, and catalysts.
  • Catalysts accelerate reactions without being consumed.

Chemical Equilibrium

  • Chemical equilibrium is the state where the forward reaction rate equals the reverse rate.
  • The equilibrium constant (K) is the ratio of product to reactant concentrations at equilibrium.
  • Le Chatelier's Principle states that a system at equilibrium will adjust to counteract any change.

Thermodynamics

  • Thermodynamics studies energy and its transformations.
  • Energy is the capacity to do work.
  • Potential energy is stored energy.
  • Kinetic energy is the energy of motion.
  • The Law of Conservation of Energy states that energy is neither created nor destroyed, only converted.
  • Enthalpy (H) measures the heat content of a system.
  • Entropy (S) measures the disorder or randomness of a system.
  • Gibbs Free Energy (G) measures the spontaneity of a reaction.
  • Spontaneous reactions occur without external energy input (ΔG < 0).
  • Non-spontaneous reactions require external energy input (ΔG > 0).

Electrochemistry

  • Electrochemistry studies the relationship between electricity and chemical reactions.
  • Oxidation is the loss of electrons.
  • Reduction is the gain of electrons.
  • Redox reactions involve both oxidation and reduction.
  • Electrochemical cells convert chemical energy into electrical energy (voltaic) or vice versa (electrolytic).
  • The anode is the electrode where oxidation occurs.
  • The cathode is the electrode where reduction occurs.

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Overview of chemistry, the study of matter and its properties. Covers branches like analytical, organic, and physical chemistry. Discusses the states and properties of matter.

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