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21 Cards in this Set
- Front
- Back
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vapor pressure depends on |
number of particles, the more particles the lower the vapor pressure. Al(NO3) < NaCl < glucose |
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how to calculate the molar fraction |
moles of solute / (Moles of solvent + moles of solute). NOTE: 10% mass of a solution means 10 to 90 no 10 to 100. |
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how to calculate molality |
molality = moles of solute / kilograms of solvent. |
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the vant hoff factor is |
estimated to be the same number as dissociated ions in a molecule but is often slightly lower realistically. |
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in molecules, higher number of particles means |
a higher boiling point |
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Calculate the vapor pressure of a solution made by dissolving 109 grams of glucose (molar mass = 180.2 g/mol) in 920.0 ml of water at 25 °C. The vapor pressure of pure water at 25 °C is 23.76 mm Hg. Assume the density of the solution is 1.00 g/ml. |
moles glucose = 109 g/ 180.2 g/mol=0.605 mass water = 920 mL x 1 g/mL = 920 g moles water = 920 g/ 18.02 g/mol=51.1 mole fraction water = 51.1 / 51.1 + 0.605 =0.988 vapor pressure solution = 0.988 x 23.76 = 23.47 mm Hg |
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what are hydrophobic colloids? what do they do? |
Hydrophobic colloids can be prepared in water only if they are stabilized in some way. Otherwise, their natural lack of affinity for water causes them to separate from the water. Hydrophobic colloids can be stabilized by adsorption of ions on their surface |
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what is henrys law? |
solubilty of a gas = constant times pressure |
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A 1.35 m aqueous solution of compound X had a boiling point of 101.4 °C. Which one of the following could be compound X? The boiling point elevation constant for water is .52 what is the formula used to solve this? |
change in temp = i times boiling point elevation constant times moles of water 1.4 = i x .52 x 1.35 i is two, compound with two particles is answer |
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when a question asks about ppm concentration what is most important to know? |
the molecular formula, CaCl2, there will be twice as many Cl as Ca
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what determines freezing point? |
the more particles formed, the lower the freezing point is |
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what is the formula for the change in temperature of a boiling point? |
Kb times molality |
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George is making spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a boil. Before adding the pasta, he adds 58 g of table salt (NaCl) to the water and again brings it to a boil. The temperature of the salty, boiling water is __________°C. Assume a pressure of 1.00 atm and negligible evaporation of water. Kb for water is .52 |
ΔTb = Kb · mB x i molality = 1 mol of NaCl per 4kg water = 0.25 x 2 for full dissociation so i = 2 ΔTb = 0.52 x 0.5 water boils at 100.26 degrees celsius |
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Determine the freezing point (°C) of a 0.015 molal aqueous solution of MgSO4. Assume i = 2.0 for MgSO4. The molal freezing-point-depression constant of water is 1.86 |
.015 times 2 = .03 .03 times 1.86 = .056 0 - .056 = -.056 |
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A solution is prepared by dissolving 0.60 g of nicotine (a nonelectrolyte) in water to make 12 mL of solution. The osmotic pressure of the solution is at 25 °C. The molecular weight of nicotine is |
7.55 = C RT = C x 0.08206 x 298 K C = 0.309 = moles nicotine / 0.0120 L moles nicotine = 0.00371 molar mass = 0.60/ 0.00371= 160 |
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what is the formula for osmotic pressure?> |
molarity times R constant times temperature K |
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The molarity of urea in a solution prepared by dissolving 16 g of urea (MW = 60.0 g/mol) in 39g of H2O is __________ M. The density of the solution is 1.3 g/mL. |
Total mass of solution, g = (mass of urea, g) + (mass of water, g) Volume of solution, mL = (mass of solution, g)/(density of solution, g/mL) Volume of solution, L = (Volume of solution, mL)*(1 L/1000 mL) Moles of Urea = (mass of urea, g)/(molecular weight of urea, g/mole) molarity of urea. moles/L = (moles of urea)/(volume of solution, L) |
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A sample of hydrogen gas is generated in a closed container by reacting 10.00 g of zinc metal with 200.0 mL of 1.00 M sulfuric acid. Calculate the solubility of hydrogen gas in the solution at 25oC if the volume over the solution is 122 mL and the Henry's constant for hydrogen in water at 25oC is 7.8 x 10–4 mol/L-atm. |
Zn + H2SO4 --> ZnSO4 + H2 Next, determine the limiting reactant: 10.00 g Zn / 65.39 g/mol = 0.1528 mol Zn 0.2000 L X 1.00 mol/L = 0.200 mol H2SO4 Zn is the limiting reactant, and you will form 0.1528 mol H2 (because everything is in a 1:1 ratio in the equation) Now, use ideal gas law to calculate pressure of the gas: PV = n RT P (0.122 L) = 0.1528 mol (0.0821 Latm/molK) (298 K P = 30.6 atm Finally, use Henry's Law to calculate the solubility of H2 in the solution: Solubility = 7.8X10^-4 mol/Latm X 30.6 atm = 0.024 M |
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When increasing coeffeicients in equilibriums..? |
Notice that every factor in the first equation is squared in the second equation, or increased by whatever square factor. |
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A sealed 2.0 L flask is charged with 0.500 mol of I2 and 0.500 mol of Br2. An equilibrium reaction ensues: When the container contents achieve equilibrium, the flask contains 0.84 mol of IBr. The value of Keq is __________. |
I2 + Br2 = 2 IBr start 0.500 . .0.500 change -x. . . . ..-x. . . . +2x 2x = 0.84 x = 0.42 ar equilibrium [Br2]= [I2]= 0.500 - 0.42 = 0.080 M Kc = (0.84)^2 / 0.080 x 0.080= 110 |
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When 2.00 mol of SO2Cl2 is placed in a 2.00l flask at 303K, 56% of the SO2Cl2 decomposes to SO2 and Cl2: SO2CL2(g) <---> SO2(g) + Cl2 (g). Calculate Kc for this reaction at this temperature. |
SO2CL2(g) <---> SO2(g) + Cl2 (g). M SO2CL2 = 2.00mole/2.00L=1 mole/L at equil: SO2CL2: 1-(0.56)1=0.44 SO2: 0.56 CL2: 0.56 K= [SO2][CL2]/[SO2CL2] = 0.56*0.56/0.44=0.713 |
