Concentrations
What concentration unit is temperature dependent? Write the equation.
Molarity = n/ V
What are the 4 colligative properties?
When the concentration of solute INCREASES, what happens for each property?
Freezing point depression
boiling point elevation
vapor pressure reduction
osmotic pressure (increases)
Given the reaction A + B ---> 2C write the rate of appearance for C.
1/2 dC/dt
What is the equation for osmotic pressure? Label all variables and units
Pi = MiRT
molarity, vant hoff, gas constant, temperature
Write the reaction in water and what kind of electrolyte this is:
CH4
CH4 --> NR
nonelectrolyte
The stockroom has a bottle of 5.42 M MgSO4. You need to make 250.0 mL of 0.85 M MgSO4. How much of the stockroom solution do you need?
0.039 L or 39 mL.
The solubility of a solid solute _____________ with increasing temperature.
The solubility of a gas solute _____________ with increasing temperature.
increases, decreases
-dA/dt
-1/2 dB/dt
1 mole of CH3OH in water
1 mole HCl in water
1 mole Mg(NO3)2 in water
Which contains the most ions?
1 mole Mg(NO3)2 has a vant hoff factor of 3
Write the reaction in water and what kind of electrolyte this is:
HClO4
HClO4 + H2O ---> H3O+ + ClO4-
Strong electrolyte
Calculate the mole fractions of ethyl alcohol, C2H5OH, and water in a solution made by dissolving 9.2 grams of alcohol in 18 grams of H2O. (Atomic Weights: H = 1, C = 12, and O = 16)
X (ethyl alcohol) = 0.1667
X (water) = 0.833
A 1 mole of CH3OH in water
B 1 mole HCl in water
C 1 mole Mg(NO3)2 in water
RANK FROM HIGHEST TO LOWEST; vapor pressure, freezing point, boiling point, osmotic pressure.
VP: A > B > C
FP: A > B > C
BP: C > B > A
OP: C > B > A
The reaction 3A + B → 2C has the rate law:
rate = k[A]^2 [B]
What is the order in A? What is the order in B? What is the overall reaction order?
A second
B first
Third order overall
Whos law allows us to calculate the vapor pressure of a solution?
Raoults law
Write the reaction in water and what kind of electrolyte this is:
C6H6
C6H6 --> NR
nonelectrolyte
Hydrochloric acid is sold as a concentrated aqueous solution. If the molarity of commercial HCl is 12.0 M and its density is 1.18 g/mL.
Calculate the molality of the solution.
16 m
A 0.55 g sample of an unknown nonelectrolyte is dissolved in 5.31 g of lauric acid. (Kf = 3.9 C/m). The freezing point depression is determined to be 4.20 C. What is the molar mass of this compound?
96.2 g/mol
The reaction A + 2 B → C has the rate law:
rate = k[A][B]
By what factor does the rate of reaction increase when both [A] and [B] are doubled?
Quadrupled
Lests say Dr. Dunlavys new cat eats cat food at a rate 3.5 times that of her old cat.
Her old cat used to eat 0.5 cans of cat food a day. How many cans of cat food does the new cat eat?
1.75 cans of cat food.
Write the reaction in water and what kind of electrolyte this is:
HF
HF <--> H+ + F-
You want to create a 55% by mass solution of MgSO4. What is the molality of this solution?
0.37 m
A solution is prepared by dissolving 35.0 g of hemoglobin in enough water to make up 1.00 L in volume. The osmotic pressure of the solution is found to be 10.0 mmHg at 25.0 °C. Calculate the molar mass of hemoglobin.
MM hemoglobin = 65,047 g/mol
Set up a rate law for the following reaction:
NH4 + (aq) + NO2 (aq) → N2 (g) + 2H2O(ℓ)
What is the overall reaction order?
Rate = k[NH4 + ]^n [NO2 − ]^m
The stockroom has a 0.75 m H2SO4 solution. What is the mole fraction of H2SO4 in this solution?
Do we assume a sample size? If so what is it?
Yes, 1kg solvent
Write the reaction in water and what kind of electrolyte this is:
Zn3(PO4)2
Zn3(PO4)2 <--> 3Zn 2+ + 2PO4 3+
weak electrolyte