General Solution Questions
What is a solution and what are the two parts of it?
A homogenous mixture of two or more components; solvent & solute
0.100 mole of NaCl is dissolved into 100.0 grams of pure H2O. What is the mole fraction of NaCl?
0.018
A 1.60 g sample of napthalene (a non-electrolyte with a formula of C10H8) is dissolved in 20.0 g of benzene. The freezing point of benzene is 5.5 °C and Kf = 5.12 kg/mol. What is the freezing point of the solution?
2.3 °C
Consider the following mechanism.
A2 + B2 → R + C (slow)
A2 + R → C (fast)
Do you have an intermediate? If yes, what? If no, explain.
R is the intermediate because it is formed in one step and used in the other.
What effects the rate of chemical reactions?
Concentration and temperature
What will lead to an increase in solubility of sodium chloride in water?
Increasing in temperature of the solution
When 2.50 grams of KMnO4 (molar mass = 158.0 g/mol) is dissolved into 100. mL of solution, what molarity results?
0.158 M
The freezing point of a 0.0925 m aqueous solution of ammonium chloride was found to be 0.325 °C. What is the actual van't Hoff factor for this salt at this concentration compared to the ideal one of 2? Kf = 1.86 °C/m
1.89
Consider the following mechanism.
A2 + B2 → R + C (slow)
A2 + R → C (fast)
What is the rate law for the overall reaction?
rate = k [A2][B2]
Explain why the rate of disappearance of NO and the rate of formation of N2 are not the same in the reaction, 2CO(g) + 2NO(g) → 2CO2(g) + N2(g).
Because of the 2:1 stoichiometric ratio between NO and N2, the NO must use 2 moles for each mole of N2 produced. This means that the rate of consumption of NO is twice as fast as the rate of production of N2.
Solvents dissolve solutes because the two substances have ________________ intermolecular interactions.
- similar
- attractive
- competing
- different
- repulsive
similar
Calculate the molality when 75.0 grams of MgCl2 is dissolved in 500.0 g of solvent.
1.58 m
Isotonic saline solution, which has the same osomotic pressure as blood, can be prepared by dissolving 0.923 grams of NaCl in enough water to produce 100.0 mL of solution. What is the osmotic pressure, in atmospheres of this solution at 25.0 °Celsius?
7.72 atm
Consider the reaction: SO2 + O3 → SO3 + O2.
A rate study of this reaction was conducted at 298 K.
The data that were obtained are shown in the table. [SO2] | [O3] |Initial Rate, mol/(L . s)
0.25 | 0.40 | 0.118
0.25 | 0.20 | 0.118
0.75 | 0.20 | 1.062
What is the rate law for this reaction?
rate = k[SO2]2[O3]0
For the reaction, A → products, a graph of [A] versus time is a curve. What can be concluded about the order of this reaction?
Since [A] vs. t is a curve, the reaction can not be zero order.
When the half of the water in a 1.0 M solution of sucrose is boiled off, what happens to the concentration of sucrose?
Increases but does not double
What is the vapor pressure of water above a solution in which 32.5 g of glycerin (C3H8O3) are dissolved in 125. g of water at 343 K? The vapor pressure of pure water at 343 K is 233.7 torr.
222.4 torr
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.
65,047 g/mol
Assume you are dealing with a first order reactant. You know your rate constant is 1.5x10-4/min, but your employer wants to the half-life of the reactant?
4.62×103 mins
A 5.00 g sample of a large biomolecule was dissolved in 16.0 g of carbon tetrachloride. The boiling point of this solution was determined to be 77.85 °C. Calculate the molar mass of the biomolecule. For carbon tetrachloride, the boiling point constant is 5.03 °C/m, and the boiling point of pure carbon tetrachloride is 76.50 °C.
1160 g/mol
M, n, mass percent, volume percent, etc.
Determine the mole fraction of H2O and CH3OH in a solution whose molality is 2.00 m.
Water = 0.965
CH3OH = 0.035
How many grams of fructose (C6H12O6) must be dissolved in 937 g of acetic acid to raise the boiling point by 9.1 °C? The boiling point constant for acetic acid is 3.08 °C/m.
499 g
Consider the reaction: 2B → C + 3D. In one experiment it was found that at 300 K the rate constant is 0.134 L/(mol. s). A second experiment showed that at 450 K, the rate constant was 0.569 L/(mol. s). Determine the activation energy for the reaction.
Ea = 10.8 kJ
Draw an exothermic graph with two steps. Label the reactants, intermediates, product, activation energies, transition states, and delta H.
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