Chapter 6 Test Flashcards
Study quizlets from every quiz in unit 6
What rule do you need to follow in Hess’ law?
Whatever you do to the equation, do it to the enthalpy change
What do you need to remember when doing the Hess’ law problems?
Look at the physical state of stuff before finalizing a problem
How do you determine limiting reactant?
Turn both substances into moles and the smallest one is the limiting reactant
What should you make sure to be careful about with all of these heat equations?
LOOK AT THE SIGNS
What is the equation for heat with phase changes?
q=m delta H
mass times enthalpy change
What does positive mean for an ion on the periodic table?
You lose an electron
What does negative mean for an ion on the periodic table?
You gain an electron
What is ground state when talking about electron configurations?
It is the normal, basic electron configuration
What results in a greater lattice enthalpy?
The greater the charge, the smaller the ion
The lattice enthalpy of LiCl is positive, indicating that it takes energy to break the ions apart in LiCl. However, the dissolution of LiCl in water is an exothermic process. Identify all particle-particle interactions that contribute significantly to the dissolution process being exothermic. For each interaction include the particles that interact and the specific type of IMFs between those particles.
There are interactions between Li+ with polar water molecules and Cl- with polar water molecules.
These are both ion-dipole interactions.
How do you calculate formal charge?
(# valence electrons)- (# lone electrons(count each dot as one) + # bonds connected(one dash counts as 1))
The sum of the formal charges of each atom should add up to zero for a molecule or add up to the charge for a polyatomic ion.
How do you determine the most valid structure based on formal charges?
Formal Charges as close to zero for all atoms. (Most preferable is “no formal charge.”) Also, negative formal charges will be placed on the most electronegative atom.
What is the most electronegative element?
Fluorine
When a question asks about the magnitude of heat energy what can you assume about the signs?
Don’t worry about the signs just the magnitude
A second student performs the experiment using the same mass of water at the same initial temperature. However, the student uses an alcohol burner containing C3H7OH(l) that is contaminated with water, which is miscible with C3H7OH(l). The difference in mass of the alcohol burner before and after the combustion in this experiment is also 0.55 g. Would the final temperature of the water in the beaker heated by the alcohol burner in this experiment be greater than, less than, or equal to the final temperature of the water in the beaker in the first student’s experiment? Justify your answer.
The final temperature measured by the second student would be less than that measured by the first student because the actual mass of C3H7OH(l) combusted will be less than .55 g.
Oxidation
OIL
Oxidation is when an atom LOSES electrons so there is an INCREASE in oxidation number
Reduction
RIG
Reduction is when an atom GAINS electrons so there is a DECREASE in oxidation number
How to write a net ionic equation?
Only include the things that weren’t repeated on both sides(aka the two aqueous things that make the solid and the solid)
Based on the arrangement of electrons in the Br and F atoms, explain why the bond length in an HBr molecule is greater than that in an HF molecule.
Br has two additional occupied electron shells (n = 3 and n = 4) compared to F (n = 2). The extra electron shells increase the distance between the H and Br nuclei, giving HBr a greater bond length.
What is happening on a heating curve during the constant parts?
Heat is being added to overcome the IMFs so that the phase can change
Molar heat capacity formula
Specific heat capacity divided by molar mass
