Exam 3 Flashcards
What are strong electrolytes?
Strong electrolytes completely dissociate into their ions in solution, leading to high conductivity.
Common examples include sodium chloride (NaCl), potassium nitrate (KNO₃), calcium chloride (CaCl₂), hydrochloric acid (HCl), and sulfuric acid (H₂SO₄).
What are weak electrolytes?
Weak electrolytes partially dissociate into ions in solution, resulting in lower conductivity.
Common examples include acetic acid (CH₃COOH), ammonia (NH₃), carbonic acid (H₂CO₃), and phosphoric acid (H₃PO₄).
What occurs during precipitate reactions?
Precipitate reactions occur when two solutions containing soluble compounds are mixed, resulting in the formation of an insoluble solid, known as a precipitate.
What is the general reaction type for precipitate reactions?
Precipitate reactions are typically classified as double displacement (or double replacement) reactions.
What factors influence precipitation?
Factors influencing precipitation include:
* Concentration
* Temperature
* pH
What is the first step in balancing a chemical equation?
Write the unbalanced equation.
What is the formula for calculating molarity?
Molarity (M) = moles of solute / liters of solution.
What is a neutralization reaction?
A neutralization reaction is a chemical process in which an acid reacts with a base to produce water and a salt.
What is the general equation for a neutralization reaction?
Acid + Base → Salt + Water.
What defines oxidation in redox reactions?
Oxidation is the loss of electrons or increase in oxidation state.
What defines reduction in redox reactions?
Reduction is the gain of electrons or decrease in oxidation state.
What are single displacement reactions?
Single displacement reactions are chemical processes where one element displaces another element in a compound.
What are double displacement reactions?
Double displacement reactions are where the ions of two compounds exchange places in an aqueous solution to form two new compounds.
What is the definition of electrolytes?
Electrolytes are substances that dissolve in water to produce ions, allowing the solution to conduct electricity.
How do strong acids behave in water?
Strong acids completely dissociate in water, releasing all of their H⁺ ions.
What is the key characteristic of weak acids?
Weak acids partially dissociate in water, establishing an equilibrium between undissociated molecules and ions.
How do strong bases behave in water?
Strong bases completely dissociate in water, releasing all of their OH⁻ ions.
What characterizes weak bases?
Weak bases partially dissociate in water, establishing an equilibrium similar to weak acids.
What is the process of dilution?
Dilution is the process of reducing the concentration of a solute in a solution by adding more solvent.
What is the formula used to express dilution?
C1V1 = C2V2.
What does stoichiometry study?
Stoichiometry studies the relationships between the quantities of reactants and products in chemical reactions.
What is a balanced chemical equation?
A balanced chemical equation has equal numbers of atoms for each element on both sides.
What is the mole ratio in stoichiometry?
The mole ratio is the ratio of moles of one substance to moles of another substance in a balanced equation.
What is titration?
Titration is a technique used to determine the concentration of a solute in a solution by gradually adding a titrant until the reaction reaches an endpoint.
What characterizes gases?
Gases have no fixed shape or volume and expand to fill their containers.
How many moles of NaOH are in 0.1 mol/L of NaOH in 25 mL?
0.0025 mol
What is the concentration of HCl if the volume is 50 mL and it contains 0.0025 mol?
0.050 M
What are the four fundamental states of matter?
- Solid
- Liquid
- Gas
- Plasma
What does the Ideal Gas Law relate?
Pressure (P), volume (V), temperature (T), and number of moles (n) of a gas
What is the Ideal Gas Law formula?
PV=nRT
What happens to the pressure of a gas in a balloon when the temperature increases?
The pressure increases if the volume is constant
What does Boyle’s Law express?
P1V1=P2V2 (at constant temperature)
What does Charles’s Law express?
V1/T1=V2/T2 (at constant pressure)
What does Avogadro’s Law express?
V1/n1=V2/n2 (at constant temperature and pressure)
What is the formula for the Combined Gas Law?
P1V1/T1=P2V2/T2 (at constant number of moles)
How many moles of gas are in a volume of 10 liters at 2 atm and 300 K?
Approximately 0.81 moles
What is the result of decreasing the volume of air in a syringe from 50 mL to 25 mL at 1 atm?
Pressure increases to 2 atm
What is the new volume of a balloon that has a volume of 4 liters at 20°C when the temperature increases to 40°C?
Approximately 4.28 L
What is the volume occupied by 3 moles of gas at standard temperature and pressure (STP)?
67.2 L
What is partial pressure?
The pressure exerted by a single gas in a mixture of gases
According to Dalton’s Law of Partial Pressures, how is total pressure calculated?
Ptotal=P1+P2+P3+…
What is mole fraction?
The ratio of the number of moles of a specific component to the total number of moles in a mixture
What is the formula for calculating mole fraction?
Xi=ni/ntotal
What is internal energy?
The total energy contained within a system, including kinetic and potential energies of its molecules
What is the first law of thermodynamics formula relating to internal energy?
ΔE=q−w
If a gas absorbs 500 J of heat and does 200 J of work, what is the change in internal energy?
300 J
What does enthalpy represent?
The total heat content of a system
What is the relationship between change in enthalpy (ΔH) and internal energy (ΔE)?
ΔH=ΔE+PΔV
What is the formula for calculating pressure-volume work?
w=−PΔV
What is the heat of a reaction (enthalpy change) at constant pressure?
Measures the heat absorbed or released during a chemical reaction
What is calorimetry?
The science of measuring the heat transfer associated with chemical reactions or physical changes
What is Hess’s Law?
The total enthalpy change for a chemical reaction is the same whether the reaction occurs in one step or multiple steps
What is bond enthalpy?
The amount of energy required to break one mole of a specific type of bond in a gaseous molecule
What is the overall ΔH for the combustion of ethylene according to Hess’s Law?
−1306.3 kJ
This value indicates that the reaction releases a significant amount of energy.
Define Bond Enthalpy.
The amount of energy required to break one mole of a specific type of bond in a gaseous molecule.
It is a measure of bond strength; higher bond enthalpy indicates a stronger bond.
What is the bond enthalpy of a carbon-hydrogen (C–H) bond?
412 kJ/mol
This means it takes 412 kJ to break one mole of C–H bonds in a molecule.
What does Enthalpy of Reaction refer to?
The heat change that occurs during a chemical reaction at constant pressure.
It can be calculated using standard enthalpies of formation or by applying bond enthalpies.
What can the enthalpy change (ΔH) indicate about a reaction?
It can be positive (endothermic, absorbs heat) or negative (exothermic, releases heat).
This indicates the nature of energy transfer in the reaction.
Calculate the ΔH for the combustion of methane (CH4) given the total enthalpy of products is -1,200 kJ and that of reactants is -890 kJ.
−310 kJ
ΔH is calculated as (Enthalpy of Products)−(Enthalpy of Reactants).
What type of reaction is indicated by the enthalpy change of -310 kJ for the combustion of methane?
Exothermic reaction
This indicates that the reaction releases heat.
Fill in the blank: Bond Enthalpy is the energy required to _______.
break bonds.
True or False: A higher bond enthalpy indicates a weaker bond.
False
Higher bond enthalpy indicates a stronger bond.
