Solution Concentration and Titration
Please define solution and explain the difference between a solute and solvent with examples.
A solution is a homogeneous mixture. A solute is the substance dissolved in a solution and the solvent is the major component in the solution. There is more of solvent and less of the solute.
Ex- Saltwater, brass, tea with sugar, etc.
Explain the differences between electrolytes and nonelectrolytes.
Explain the differences between weak and strong electrolytes.
Electrolytes are substances that dissolve in water to produce conducting solutions of ions. Nonelectrolytes are substances that do not produce ions in aqueous solutions.
Strong electrolytes are compounds that dissociate to a large extent into ions when dissolved in water. Weak electrolytes are compounds that dissociate to a small extent into ions when dissolve in water.
Define wavelength, frequency and amplitude.
Wavelength is the distance between two peaks or two troughs on a wave. Frequency is the number of wave peaks that pass a given point per unit time. Amplitude is the height of the wave from the center.
Describe quantum numbers n, l, ml and ms, as well as give some examples of what the numbers l, ml and ms given n=2.
Angular-Momentum Quantum Number, l, defines the three dimensional shape of the orbital, commonly called a subshell, l can range from 0 to n-1.
Magnetic quantum number, ml, defines the spatial orientation of the orbital, values can range from -l to +l.
Spin quantum number, ms, tells the spin direction of the electron, is either +1/2 or -1/2.
Example: l = 0,1; ml = -1,0,1; ms = -1/2,+1/2
Explain electron dot structures.
Represents an atoms valence electrons by dots and indicates by the placement of the dots the way the valence electrons are distributed in a molecule.
Bonus points if you can also explain and give the formula for diluting a concentrated solution.
Molarity the number of moles of substance dissolved in each liter of solution. It tells us about the concentration of a solution.
M=Moles of Solute/Liters of Solution
Bonus: Diluting a concentrated solution involves adding more of the solvent to the solution. Mi*Vi=Mf*Vf or CV1=CV2
Identify which of the following compounds are soluble and which are insoluble.
HCl, AgCl, NaOH, MgCO3
HCl - Soluble
AgCl - Insoluble
NaOH - Soluble
MgCO3 - Insoluble
0.9*10^34 Hz
Give the subshell letter associated with the quantum number l.
l=0, l=1, l=2, l=3
For l=1 and l=1 give the shape associated with that subshell.
l=0 is s subshell and has a circular shape
l=1 is p subshell and has a dumbbell shape
l=2 is d subshell
l=3 is f subshell
Draw an electron dot structure for SF6 and PO43+.
Define titration.
A procedure for determining the concentration of a solution by allowing a measured volume of that solution to react with a second solution of another substance whose concentration is known.
Explain the differences between molecular, ionic and net ionic equations.
Molecular equations include all substances in the chemical equation written using their complete formula as if they were molecules.
Ionic equations include all of the strong electrolytes written as ions.
Net ionic equations only show the ions undergoing change.
Calculate the wavelength of light emitted by the energy transition from n=2 to n=1 for a hydrogen atom.
1.215*10^-7 m
What is the ground state electron configuration of tellurium?
Explain free radicals, draw a dot structure for NO2 and use it to help explain free radicals.
Free radicals are single unpaired electrons and will always leave an atom with an unfilled octet.
Calculate the grams of solute needed to prepare 225mL of 0.400M KBr solution.
10.710g KBr
Write the net ionic equation for
AgNO3(aq) + KCl(aq) -> AgCl(s) + KNO3(aq)
Ag+(aq) + Cl-(aq) -> AgCl(s)
Given the list of threshold frequencies for different metals, electromagnetic radiation with a wavelength of 785 nm will eject electrons from the surface of which of the follow metals?
None of them.
What is the electron configuration of Fe2+?
[Ar]3d6
Explain resonance structures. Draw a dot structure for O3 to help explain.
Resonance structures are structures for compounds that can appear in a few different forms. Certain structures are more stable than others and formal charge can be used to determine which structure is most stable.
How much water would need to be added to 500mL of a 2.4M KCl solution to make a 1M solution?
700mL, the final volume would be 1200mL.
Complete the reaction and write the net ionic equation for
MnCl2(aq) + (NH4)2CO3(aq) ->
Mn(aq)2+ + CO3(aq)2- -> MnCO3(s)
The greater the energy of a photon, the
A. shorter the wavelength and the higher the frequency
B. longer the wavelength and the higher the frequency
C. shorter the wavelength and the lower the frequency
D. longer the wavelength and the lower the frequency
A. shorter the wavelength and the higher the frequency
Which electron could be assigned to the following quantum numbers?
n=4, l=1, ml=0, m2=+1/2
4
Explain formal charge and draw a structure for OCN-, assigning formal charges to help explain this.
Formal charge helps us determine the most stable dot structure of a compound.