Semester 2 chem final
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90 Terms
What is a reactant?
The elements/compounds that start a reaction.
What is a product?
The elements/compounds that end a reaction.
List the 7 diatomic elements.
Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), Iodine (I2).
What does (s) mean in a chemical equation?
Solid.
What does (l) mean in a chemical equation?
Liquid.
What does (g) mean in a chemical equation?
Gas.
What does (aq) mean in a chemical equation?
Aqueous.
What is meant by the term 'aqueous'?
In aqueous solution; dissolved in water.
What are the numbers used to balance a chemical equation called?
Coefficients.
What are the numbers used to signify how many of each atom are in a compound called?
Subscripts.
What is a synthesis reaction?
Two elements or compounds combine to make one compound.
What is the 'ABC' version of a synthesis reaction?
A + B → AB.
What is a decomposition reaction?
One compound (reactant) falls apart into two or more elements or compounds.
What is the 'ABC' version of a decomposition reaction?
AB → A + B.
What is a single replacement reaction?
One element replaces another in a compound; reactants must be an element and a compound.
What is the 'ABC' version of a single replacement reaction?
A + BC → B + AC.
What is a double replacement reaction?
Two things replace each other; reactants must be two ionic compounds or acids.
What is the 'ABC' version of a double replacement reaction?
AB + CD → AD + CB.
What is a combustion reaction?
A reaction in which a compound (often carbon-based) reacts with oxygen; products are always CO2 and H2O.
What is the 'ABC' version of a combustion reaction?
CH4 + O2 → CO2 + H2O.
What is a catalyst?
What happens to a catalyst when it is added to a reaction?
A substance that speeds up the reaction rate by lowering the activation energy.
It isn't changed; it isn't considered a reactant or a product
What are the observations that indicate a chemical reaction has occurred?
Emission of light or heat, formation of a gas, formation of a precipitate, color change, emission of odor.
What are the products of all combustion reactions?
CO2 and H2O.
What are the factors that increase a reaction rate?
Temperature, concentration, surface area, catalysts, pressure.
Hydrogen Bonds
A strong type of dipole-dipole attraction between molecules that occurs when a hydrogen atom is bonded to a highly electronegative atom.
Single Covalent Bond
A bond formed by the sharing of one pair of electrons between two atoms.
Double Covalent Bond
A bond formed by the sharing of two pairs of electrons between two atoms.
Polar Covalent Bond
A type of covalent bond where electrons are shared unequally, resulting in a dipole moment.
Nonpolar Covalent Bond
A type of covalent bond where electrons are shared equally between two atoms.
Metallic Solids
Solids composed of metal atoms that are held together by metallic bonds, characterized by high electrical conductivity and malleability.
Molecular Solids
Solids composed of molecules held together by intermolecular forces, typically having lower melting points.
Ionic Solids
Solids composed of ions held together by ionic bonds, characterized by high melting points and electrical conductivity when melted or dissolved.
Dipole-Dipole Forces
Intermolecular forces that occur between polar molecules, where positive and negative ends attract each other.
London Dispersion Forces
Weak intermolecular forces arising from temporary dipoles in molecules, present in all molecular substances.
Unique Properties of Water
High surface tension, cohesion, adhesion, high boiling point, high specific heat, high heat of vaporization, less dense when frozen, and being a universal solvent.
Viscosity
A measure of a fluid's resistance to flow, which decreases with an increase in temperature.
Allotropes
Different forms or structures of the same element, such as graphite and diamond for carbon.
Polar Molecule
A molecule with an unequal distribution of charge, resulting in the molecule having a positive end and a negative end
What is an exothermic reaction?
An exothermic reaction releases heat.
What is an endothermic reaction?
An endothermic reaction absorbs heat.
What is the potential chemical energy of reactants in endothermic reactions?
It is less than that of the products.
What is the potential chemical energy of reactants in exothermic reactions?
It is greater than that of the products.
What is enthalpy?
Enthalpy is the heat content of a system at constant pressure.
What is the sign of ΔH for exothermic reactions?
ΔH is negative.
What is the sign of ΔH for endothermic reactions?
ΔH is positive.
What is calorimetry?
Calorimetry is the measurement of heat absorbed or released during a chemical reaction.
What does heat (q) represent?
Heat (q) is the amount of energy transferred from one object to another due to a difference in temperature.
What is a calorie?
A calorie is the amount of energy required to raise 1g of water by 1°C. A common unit of energy.
What is the heat of vaporization?
It is the amount of heat necessary to vaporize one mole of a given liquid.
What is the heat of fusion?
It is the heat absorbed by one mole of a solid substance as it melts to a liquid at a constant temperature.
What is the critical point?
The critical point is where liquid and vapor exist together.
What is the triple point?
The triple point is where all three phases exist together.
What does the equation q = mcΔT represent?
It represents the heat transfer in a substance.
What is the relationship between energy in exothermic and endothermic reactions?
Energy released in an exothermic reaction was once stored in the chemical bonds of the reactants; energy absorbed in an endothermic reaction is stored in the chemical bonds of the products.
How do you calculate heat transfer using mass and specific heat?
q = mcΔt.
What is a calorimeter?
An instrument used to measure changes in thermal energy
Desposition
gas to solid
Sublimation
solid to gas
condensation/vaporization
gas to liquid/liquid to gas
Energy is , to break bonds, while energy is to form bonds.
absorbed, released
List the SI unit used for heat and energy
Joule
1 calore = ___ Calores
1,000
Freezing/melting
liquid to solid/solid to liquid
Heat
The energy transferred between objects that are at different temperatures
What are the four points regarding Ideal Gas molecules according to the Kinetic Molecular Theory?
- Motion of molecules: A gas consists of molecules traveling in straight-line motion and obeying Newton's Laws. 2. Volume of molecules: The molecules in a gas occupy no volume (they are points). 3. Collisions of molecules: Collisions between molecules are perfectly elastic (no energy is gained or lost). 4. Forces between molecules: There are no attractive or repulsive forces between the molecules.
In what units must temperature be for gas law problems?
Kelvin.
How do you convert from °C to K?
K = °C + 273.
How do you convert from K to °C?
°C = K - 273.
List all standard pressure values that need to be memorized.
760 mmHg, 14.7 psi, 1 atm, 101.3 kPa, 101,300 Pa.
What are the two 'R' values used in the Ideal Gas Law equation?
0.0821 L⋅atm/mol·K and 8.314 L·Pa/mol·K.
What is the Combined Gas Law?
It expresses the relationship between pressure, volume, and temperature of a fixed amount of gas. Equation: P1V1/T1 = P2V2/T2.
What is Boyle's Law?
Gas pressure is inversely proportional to volume when temperature is held constant. Equation: P1V1 = P2V2.
What is Charles' Law?
The volume of a fixed mass of gas is directly proportional to the Kelvin temperature when pressure is held constant. Equation: V1/T1 = V2/T2.
What is Gay-Lussac's Law?
The pressure and Kelvin temperature of a gas are directly proportional, provided that the volume remains constant. Equation: P1/T1 = P2/T2.
What is Avogadro's Law?
It identifies the relationship between the volume and the amount of a gas. Equal volumes of gases contain equal numbers of particles.
What is the Ideal Gas Law?
Pressure times Volume equals the number of moles (n) times the Ideal Gas Constant (R) times the Temperature in Kelvin. Equation: PV = nRT.
What is Dalton's Law of Partial Pressures?
The sum of the partial pressures of gases in a mixture is equal to the total pressure of the mixture of gases. Equation: PTotal = P1 + P2 + P3 + …
What would be the volume at STP of a gas with a pressure of 370 torr at 27 °C occupying 400 mL?
1200 mL.
What would be the new volume of a gas sample with a volume of 20 mL at 2 atm if the pressure is changed to 0.2 atm?
200 mL.
What is the new volume of a soccer ball that has a volume of 1.5 liters at 21°C when taken outside to 37°C?
1.6 L.
Which gas has the smallest volume at STP: 5 g of NH3 or 5 g of CO2?
5 g of NH3.
What is the volume in liters of 25 grams of iodine gas at STP?
2.2 L.
Calculate the pressure in kPa of 1.5 moles of chlorine gas in a 0.50 liter flask at 25.0 °C.
7,432.72 kPa.
What is the temperature in °C of 12 grams of carbon dioxide gas in a 5,000 mL container at 210 kPa?
200 °C.
How many moles of gas are in a balloon filled with 0.25 liters at 2 atm and -15 °C?
0.02 mol.
How many grams of hydrogen gas were used to fill a 2,570 mL balloon at -22.7°C with a pressure of 999 torr?
10.332 g.
What is the total pressure of a mixture of nitrogen (300 mm Hg), oxygen (200 mm Hg), and hydrogen (100 mm Hg)?
600 mm Hg.
What is the partial pressure of oxygen if the atmospheric pressure is 444 torr and oxygen makes up 11% of the air?
48.84 torr.
What is the partial pressure of helium in the atmosphere if the total pressure is 877 kPa, and the partial pressures of oxygen and nitrogen are 159 kPa and 542 kPa?
176 kPa.