Gen Chem 1a Riverside Community College Midterm 2

Openstax che-2e is used as textbooko

what is a complete ionic equation

A complete ionic equation is a chemical equation that shows all the ions present in a solution, including both the reactants and products, indicating how they dissociate in an aqueous solution.

what is a net ionic equation?

A net ionic equation is a chemical equation that shows only the ions and molecules that participate in a chemical reaction, omitting the spectator ions. It illustrates the actual chemical change taking place in a solution.

What is ionization in acid-base reactions?

Ionization is when an acid releases H+ ions, (H₃O⁺ because H+ is unstable).

what is dissociation in acid-base reactions?

When a base releases OH- ions in a solution

What is the form of a neutralization reaction

acid + base → salt + water

What is oxidation

When an element gains oxidation state by loosing electrons

What is reduction

When an element loses oxidation number by gaining electrons

What is an oxidation and reduction agent

An oxidation agent gains electrons (reduces) for other terms to oxidize

A reduction agent looses electrons (oxidizes) for other terms to reduce

What are the steps for balancing a redox reaction in acid

1. Write the 2 half-reactions for the reducing and oxidizing terms

2. Balance any elements on both sides of the half-reaction that aren’t oxygen or hydrogen

3. Add water on one side to balance oxygen

4. Add H+ ions on one side to balance hydrogen

5. Add electrons to balance charge

6. Combine half-reactions, simplify H2O and H+ as well as e-

What are the steps for balancing a redox reaction in base

1. Write the 2 half-reactions for the reducing and oxidizing terms

2. Balance any elements on both sides of the half-reaction that aren’t oxygen or hydrogen

3. Add water on one side to balance oxygen

4. Add H+ ions on one side to balance hydrogen

5. Add electrons to balance charge

6. Combine half-reactions, simplify H2O and H+ as well as e-

7. Add enough OH- ions to combine with H+ on both sides

8. Simplify by combing OH- ions with H+ ions to make water

What is heat (q) defined as

A transfer of thermal energy between two bodies at different temperatures

What does a negative heat (-q) mean

an exothermic process is taking place

What does a positive heat (+q) mean

An endothermic process is taking place

What is heat-capacity (C)

An extensive property defined as the amount of heat an object needs to absorb to raise by 1 degree celsius. J/C

What is specific heat capacity c

An intensive property which is the amount of heat required to raise 1 gram of a substance by 1C. J/gC

What is the equation for calorimetry in a styrofoam setup and real setup.

1. In a styrofoam (complete insulation) setup: q_{reaction/system}= -q_surroundings

2. In a real setup: q_system= -(q_insides+q_{calorimetry setup})

what is internal energy

Internal energy is the sum of all possible energies in a substance

\Delta U=q+w

What is expansion work

When a system pushes back on the surroundings because of a restraining pressure

What is a state function

A function that depends only on what state the system is in, not how it is reached

What is the definition enthalpy

Enthalpy is a state function equal to the sum of internal energy and pressure times volume

H=U+PV

But because expansion work cancels out PV, under constant pressure, it is said that enthalpy just equals heat

\Delta H=q

What is standard state change of enthalpy

\Delta H^{o} is the change of enthalpy under standard conditions.

• The standard state change of formation & combustion are for 1 mol of the forming or combusting substance

What is the standard enthalpy of formation

The change of enthalpy required to form 1 mol of a pure substance from it’s free components in their most stable states under STP conditions

What does λ refer to in a wave

λ is the wavelength of a wave

What does ν refer to in a wave

v is the frequency of a wave

What is the relationship between frequency and wavelength in a wave

c=\lambda\nu Where c is the speed of light within a vacuum, lambda is the wavelength, and nu is the frequency

What is the formula for the energy of a photon given either frequency or wavelength?

E=h\nu;

E=\frac{hc}{\lambda}

What is the equation for the energy of a photon emitted based on the energy level changes of the electron

\Delta E=E_{f}-E_{i}=h\nu=\frac{hc}{\lambda}

E_f is the final energy level of the electron

E_i is the initial energy level of the electron

What is the energy of an electron based on it’s principal energy level

E_{n}=-\frac{kZ^2}{n^2} where n is the principal energy level, k is the constant (Rydenbergs constant for atoms with one electron), and Z is the amount of protons in the atom

What is the combined equation to find the energy of a photon given principal energy changes

\Delta E=k\left(\frac{1}{n_1^2}-\frac{1}{n_2^2}\right)=\frac{hc}{\lambda}=h\nu

Where k is rydenbergs constant

Where n is the principal energy level