Practice exam 3

If 5.20 g of HCl is added to enough distilled water to form 3.00 L of solution, what is the molarity of the solution? [Molecular weight: HCl, 36.46 amu] -0.143 M -0.0475 M -0.428 M -2.34 M -1.73 M

.0475 M

Enough water is added to 50.0 mL of a 0.660 M NaOH solution in order to bring the total volume to 450.0 mL. What is the molarity of this diluted solution? -0.594 M -0.0733 M -5.94 M -0.0330 M -0.660 M; the molarity remains unchanged if only solvent is added.

0.0733 M

What is the molarity of a solution if 300.0 mL of it contains 16.8 g of KNO3? [Formula weight: KNO3, 101.11 amu] -5.53 × 10−4 M -0.554 M -0.056 M -0.166 M -5.66 M

0.554 M

What is the boiling point of a 1.5 m solution of NaCl? [kb = 0.52°C/m] -101.56°C -100.52°C -99.22°C -100.78°C -98.44°C

100.52?

A candy sample is completely combusted in a bomb calorimeter. The calorimeter contains 982 g of water, and the measured temperature increase is 2.62°C. What is the fuel value of the candy sample in nutritional Calories? [SHw = 1.00 cal/(g•°C)] -2.57 Cal -2.67 × 10−6 Cal -2573 Cal -2570 Cal -0.00267 Cal

2.57 Cal

Ethylene glycol has a specific heat of 0.578 cal/(g•°C). If 23.2 g of ethylene glycol absorbs 75.6 cal of heat energy, what will the temperature increase be? -0.177°C -5.64°C -1.88°C -1.01 × 103°C -3.03 × 103 °C

5.64°C

Which of the following represents an exothermic reaction? (g) + B(g) → 2C(g) ∆H = +100 kcal and A(g) → B(g) + 33 kcal are exothermic reactions. A(g) + B(g) → 2C(g) ∆H = +100 kcal and 50 kcal + 2A(g) → C(g) + D(s) are exothermic reactions. A(g) → B(g) + 33 kcal A(g) + B(g) → 2C(g) ∆H = +100 kcal 50 kcal + 2A(g) → C(g) + D(s)

50 kcal + 2A(g) → C(g) + D(s) NOT CORRECT

A student needs to prepare 250.0 mL of a 2.50 M HCl solution using the stock solution 12.0 M HCl. What volume of 12.0 M HCl is required for this dilution? -5.21 mL -25.0 mL -52.1 mL -12.0 mL -2.50 mL

52.1 mL

If the concentration of Mg2+ in solution is 3.0 × 10-3 M, what is its concentration expressed in meq/L? -6.0 × 10-6 meq/L -3.0 meq/L -6.0 meq/L -1.5 meq/L -1.5 × 10-6 meq/L

6.0 meq/L

Which statement concerning solution concentration is FALSE? -A saturated solution contains more than 100 g of dissolved solute. -The molarity of a solution is the number of moles of solute present in one liter of the solution. -A solution can be made less concentrated by adding additional solvent. -The concentration of a saturated solution is equal to the solubility of the solute. -An unsaturated solution contains less than the maximum amount of solute that can be dissolved in the solvent.

A saturated solution contains more than 100 g of dissolved solute.

The formation of rust (Fe2O3) on an exposed piece of metal typically takes several months. Which of the following statements is NOT a reasonable assumption about this chemical reaction? 4Fe(s) + 3O2(g) → 2Fe2O3(s) -The rusting of iron would occur faster in the warmer summer months than in the cooler winter months. -The reaction has low activation energy. -The reaction has a low reaction rate. -The rusting of iron would occur slower at higher altitudes where the concentration of oxygen is lower. -Adding a catalyst would increase the rate of the formation of rust.

Adding a catalyst would increase the rate of the formation of rust. NOT CORRECT

The reaction shown below is at equilibrium. Use LeChatelier's principle to predict the effect of adding ammonia gas to the equilibrium reaction mixture. N2 (g) + 3H2 (g) arrow 2NH3 (g) -Vitamin D is likely a nonpolar substance. -Vitamin D is likely a bipolar substance. -It is impossible to say anything about the polarity of Vitamin D without knowing its structure. -Vitamin D is likely a polar substance. -Vitamin D is likely an ionic compound.

The equilibrium constant will increase. NOT CORRECT

The rate of a chemical reaction increases with an increase in concentration of one or more of the reactants. This is best explained by which of the following statements? -The increased concentration of the reactants increases the speed of the molecules. -The increased concentration of the reactants increases the activation energy of the reaction. -The increased concentration of the reactants decreases the activation energy. -The increased concentration of the reactants increases the temperature of the molecules. -The increased concentration of the reactants increases the frequency of effective collisions.

The increased concentration of the reactants increases the frequency of effective collisions.

Which statement concerning solution concentration is TRUE? Multiple Choice -If a solution is 12% (m/m) it will also be 12% (m/V). -The ppm unit of concentration is typically used for very high concentrated solutions. -A 1.0 ppm solution is more concentrated than a 1.0% (m/m) solution. -A solution that is 1 ppt is less concentrated than a solution that is 1 ppm. -If a bottle is labeled 0.10 M Ba(OH)2, the concentration of OH- ions in solution is 0.20 M.

The ppm unit of concentration is typically used for very high concentrated solutions. NOT CORRECT

A student mixes 4.0 g of KNO3 with 5.0 mL of water at room temperature, and observes that most, but not all, of the KNO3 has dissolved. Which statement concerning this solution is TRUE? -In order to get the additional KNO3 to dissolve, the student can add more solute. -KNO3 is a water insoluble ionic compound. -The solubility of KNO3 in water has been exceeded. -The solution is considered unsaturated, since not all of the KNO3 dissolved. -The solution is considered supersaturated, since no additional KNO3 will dissolve.

The solubility of KNO3 in water has been exceeded.

For the reaction A(g) → 2B(g), Keq = 4.5 × 105. Which statement is TRUE for the system at equilibrium? -Changing the temperature will have no affect on the equilibrium. -There is twice as much B as there is A in the reaction vessel. -There is more than 100 times more B than there is A in the reaction vessel. -There is twice as much A as there is B in the reaction vessel. -[A] >> [B]

There is more than 100 times more B than there is A in the reaction vessel.

Vitamin D is essential for the normal development of teeth and bones. A tablet of Vitamin D is tested for its solubility in water and benzene. The results are shown in the table below. What is the most appropriate interpretation of the solubility results? -Vitamin D is likely a nonpolar substance. -Vitamin D is likely a bipolar substance. -It is impossible to say anything about the polarity of Vitamin D without knowing its structure. -Vitamin D is likely a polar substance. -Vitamin D is likely an ionic compound.

Vitamin D is likely a nonpolar substance

Which of the following statements concerning the reversible reaction below is FALSE? -At the start of the reaction, the forward reaction rate is greater than the reverse reaction rate. -As the reaction progresses and the concentration of NO2 increases, the rate of the reverse reaction increases. -As the reaction progresses and the concentration of N2O4 decreases, the rate of the forward reaction decreases. -When the reaction reaches equilibrium, the concentrations of NO2 and N2O4 are equal. -The forward reaction produces NO2, and the reverse reaction produces N2O4.

As the reaction progresses and the concentration of NO2 increases, the rate of the reverse reaction increases. NOT CORRECT

What is the equilibrium constant expression for the reaction shown below? MgCO3 (s) --> MgO (s) + CO2 (g)

CO2

What is the name and symbol of the thermodynamic quantity that represents the heat absorbed or liberated in a chemical reaction at constant pressure? -None of the choices are correct. -Enthalpy Change, ∆H -Entropy Change, ∆S -Free Energy Change, ∆G -Enthalpy Change, ∆H and Entropy Change, ∆S.

Enthalpy Change, ∆H

What thermodynamic quantity is the ultimate predictor of reaction spontaneity? -Enthalpy Change, ∆H -Entropy Change, ∆S -Free Energy Change, ∆G -None of the choices are correct. -Entropy Change, ∆S and Free Energy Change, ∆G.

Free Energy Change, ∆G

Which of the following is a process with a negative ∆S? -None of the choices are correct; ∆S cannot be negative. -CaCO3(s) → CaO(s) + CO2(g) -CO2(s) → CO2(g) -H2O(l) → H2(s) -dissolving sugar in water

H2O(l) → H2(s)

What is the law that states that vapor pressure of the solvent decreases in proportion to the concentration of the solute? -Boyle's Law -Raoult's Law -Dalton's Law -Tyndall's Law -Henry's Law

Raoult's Law

Which of the following is a TRUE statement concerning the specific heat of a substance? -Specific heat is the amount of heat required to raise one gram of a substance by one degree Celsius. -Specific heat is the heat given off in a chemical reaction. -Specific heat is 1.00 cal for all substances. -Specific heat is the amount of heat required to raise one mole of a substance by ten degrees. -Specific heat is the change in the temperature of a substance as it absorbs heat.

Specific heat is the amount of heat required to raise one mole of a substance by ten degrees NOT CORRECT

An unknown amount of water is added to 75 mL of a 3.5 M sodium chloride solution. What can be said for certain about the concentration of the solution that results? -The concentration of the resulting solution will be greater than 3.5 M. -The concentration of the resulting solution will be 0.26 M. -The concentration of the resulting solution will be 3.5 M because the amount of glucose has not changed. -It is impossible to say anything for certain about the concentration because the amount of water that was added is unknown. -The concentration of the resulting solution will be less than 3.5 M.

The concentration of the resulting solution will be less than 3.5 M.

Which of the following properly describes a colligative property of a solution? -a solution property that depends on the identity of the solute particles present -a solution property that depends on the concentration of solute particles present -a solution property that depends on the concentration, identity, and pressure of the solute particles present -a solution property that depends on the pressure of the solute particles present -a solution property that depends on the electrical charges of the solute particles present

a solution property that depends on the concentration of solute particles present

What instrument is used for measuring the heat energy absorbed or released in a chemical reaction? -thermometer -calorimeter -scale -thermos -balance

calorimeter

What type of liquid displays the Tyndall effect? -colloidal suspension -homogeneous mixture -solution -pure substance -heterogeneous mixture

colloidal suspension

Which of the following is NOT a colligative property of a solution? -boiling point elevation -osmotic pressure -conductivity -vapor pressure lowering -freezing point depression

conductivity

In general, which state of matter has the lowest entropy? -plasma -solid -gas -liquid -supercritical fluid

solid

Under normal conditions, which of the following would have the highest entropy? -steam -solid sodium chloride -ice -solid iron -liquid water

steam

Which one of the following, if changed, would change the value of the equilibrium constant, Keq, of a reaction? -concentration of the products -size of reaction vessel -concentration of reactants -temperature -catalyst

temperature

One mole of sodium chloride is added to 100 mL of water in beaker A. One mole of glucose, C6H12O6, is added to 100 mL of water in beaker B. How much more will the freezing point of water be lowered in beaker A than in beaker B? -Beakers A and B will experience the same degree of freezing point depression. -twice as much -three times as much -two thirds as much -It is impossible to determine.

twice as much