CHEM 111 Exam 2 review UPDATED ACTUAL QUESTIONS AND CORRECT ANSWERS
What is molarity? the number of moles of solute per liter of solution. (moles/ liter); concentration of
a solution.
What's the molarity of a solution with 100.0 g of CH3OH 100.0 g CH3OH (1mol CH3OH/32 g) = 3.215 moles CH3OH
dissolved in 500 mL of water?
3.215/ .500 L = 6.25 M
How many grams of CH3OH are there in 100 mL of .5 M 1.6 g of CH3OH
solution?
What's the concentration of Cl- ions in .25 M CaCl2 .5 M of Cl- ions
solution?
What's the ideal gas law? PV=nRT
*R=.0821
Pressure volume = moles constant * temperature (K)
, How are pressure and volume of a gas related? inversely related; as pressure increases the volume decreases
How are pressure and temperature of a gas related? directly related; as temperature increase so does pressure. (particle collide more
are temperature increase, so there are more collisions with the container walls)
How do colvalent and ionic substances behave in water? Covalent substances don't break apart and ionic substances break apart into ions.
Also refer to solubility rules for exceptions to this rule.
Does CH3OH break into ions in water? no because it's a covalent compound
Does CaCO3 break into ions in water? no carbonate isn't soluble *solubility rules
Does AgCl break into ions in water? no Ag is not soluble *solubility rules
Does SrF2 break into ions in water? no not soluble *solubility rules
Does Pb(NO3)2 break into ions in water? yes, it's soluble
What is the formula used for dilutions? M1V1 = M2V2
Find the final concentration if 100 mL of .05 M NaCl is M1V1 = M2V2
diluted to 500 mL. (.05M)(100mL) =(M2)(500mL)
M2 = .01 M
Find the final concentration if 100 mL of water is added to M1V1 = M2V2
200 mL of .05 M NaCl. (.05M)(200mL) =(M2)(200 + 100 mL)
*final solution is 300 mL
M2=.033 M
Find the final concentration of NaCl if 100 mL of .05 M *This is NOT a dilution
NaCl is mixed with 50 mL of 1.0 M NaCl final moles/ final volume(L) (M= moles/L)
.05 M = x moles/ .100 L
.005 moles NaCl in the .05 M solution
1.0 M = x moles/.050 L
.05 moles of NaCl in the 1.0 M solution
(.005 + .05)/ (.100 L + .050 L)= .37 M
At a constant temperature, 12.5 L of N2 at .30 atm is PV=nRT
compressed to 4.15 L. What is the final pressure? *since the variables we're interested in are on the same side you set it up like ...
P1V1=P2V2
P1V1=P2V2
(.30atm)(12.5L) = (P2)(4.15L)
P2= .90 atm
What is molarity? the number of moles of solute per liter of solution. (moles/ liter); concentration of
a solution.
What's the molarity of a solution with 100.0 g of CH3OH 100.0 g CH3OH (1mol CH3OH/32 g) = 3.215 moles CH3OH
dissolved in 500 mL of water?
3.215/ .500 L = 6.25 M
How many grams of CH3OH are there in 100 mL of .5 M 1.6 g of CH3OH
solution?
What's the concentration of Cl- ions in .25 M CaCl2 .5 M of Cl- ions
solution?
What's the ideal gas law? PV=nRT
*R=.0821
Pressure volume = moles constant * temperature (K)
, How are pressure and volume of a gas related? inversely related; as pressure increases the volume decreases
How are pressure and temperature of a gas related? directly related; as temperature increase so does pressure. (particle collide more
are temperature increase, so there are more collisions with the container walls)
How do colvalent and ionic substances behave in water? Covalent substances don't break apart and ionic substances break apart into ions.
Also refer to solubility rules for exceptions to this rule.
Does CH3OH break into ions in water? no because it's a covalent compound
Does CaCO3 break into ions in water? no carbonate isn't soluble *solubility rules
Does AgCl break into ions in water? no Ag is not soluble *solubility rules
Does SrF2 break into ions in water? no not soluble *solubility rules
Does Pb(NO3)2 break into ions in water? yes, it's soluble
What is the formula used for dilutions? M1V1 = M2V2
Find the final concentration if 100 mL of .05 M NaCl is M1V1 = M2V2
diluted to 500 mL. (.05M)(100mL) =(M2)(500mL)
M2 = .01 M
Find the final concentration if 100 mL of water is added to M1V1 = M2V2
200 mL of .05 M NaCl. (.05M)(200mL) =(M2)(200 + 100 mL)
*final solution is 300 mL
M2=.033 M
Find the final concentration of NaCl if 100 mL of .05 M *This is NOT a dilution
NaCl is mixed with 50 mL of 1.0 M NaCl final moles/ final volume(L) (M= moles/L)
.05 M = x moles/ .100 L
.005 moles NaCl in the .05 M solution
1.0 M = x moles/.050 L
.05 moles of NaCl in the 1.0 M solution
(.005 + .05)/ (.100 L + .050 L)= .37 M
At a constant temperature, 12.5 L of N2 at .30 atm is PV=nRT
compressed to 4.15 L. What is the final pressure? *since the variables we're interested in are on the same side you set it up like ...
P1V1=P2V2
P1V1=P2V2
(.30atm)(12.5L) = (P2)(4.15L)
P2= .90 atm
