Chapter 10 Problems

20 original chapter problems from Chemistry II, Chapter 2. Review quizzes remain in their original lessons.

Original reading → · Source answers and worked examples →

1. What is the solubility of $NaCl$ ($K_{sp}=37.3$) in a 1M solution of $MgCl_2$ ?

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2. AP edition reviewed standalone replacement.

   At fixed temperature and solvent composition, explain how crushing and stirring can speedMgCl₂ dissolution. Does a faster rate prove a greater equilibrium solubility? Give the particle/transport explanation.

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3. You have $15L$ of water, and you add 41mol of $LiBr$ and 10mol of $PbCl_2$ . After bringing the solution to equilibrium, you find out you have $2.5kg$ of the less soluble salt left. What is the new boiling point of the solution?

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4. A solution of 0.3M $NaOH$ and 0.75M $MgCl_2$ is saturated with $NaCl$ ($K_{sp}=37.3$). What is the concentration of $NaCl$ in the solution?

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5. You have 5L of water, 200g of $KCl$ ($K_{sp}=21.7$), 400g of $KOH$ ($K_{sp}=364$), and 330g of $K_2SO_4$ ($K_{sp}=1.32$). After adding two salts, you are able to completely dissolve them. The third salt is unable to be fully dissolved in the solution. Which salt is left, and how much is left undissolved?

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6. Acid rain can occur if the concentration of $HCl$ exceeds $10^{-4}M$ . What would the concentration (in ppm) need to be in the air for acid rain to develop. Assume $P=0.9atm$ , and $T=10^\circ C$ .

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7. An evaporation tower is used to strip dissolved gas from water. If a water treatment plant is removing $H_2S$
   ($k_{H,\ 298}=11.49,\ C=2100$) from groundwater, what is the minimum concentration that can be met if they heat up the water during the process to $30^\circ C$ ? In ambient air, H2S has a concentration of $2\cdot10^{-4} mol\%$.

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8. How much does the concentration of Carbon Dioxide change throughout the year if pressure is constant at 0.9 atm (remember $CO_2$ makes up $0.03\%$ of the atmosphere)? The maximum temperature is $32^\circ C$ and the minimum temperature is $2^\circ C$ .

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9. At what temperature will the solubility of $HCl$ exceed $NH_3$?

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10. If seawater is about $3.5\%$ by weight $NaCl$ , the rest being water, what is the freezing point?

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11. You have three solutions of the same compound at varying molarities. Name two ways you can easily rank the three solutions in order of increasing concentration if you only know the compound involved in the solution?

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12. A chemist decides he wants to invent a new type of windshield washer fluid that won’t freeze in a Russian winter. If he wants to use $MgCl_2$ and Aluminum Sulfate at a $2:1$ ratio by mass, what will the molality of $MgCl_2$ be if winter can reach $-68^\circ C$ ?

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13. A beaker of water is held under $0.05atm$ of $NH_3$ gas. What temperature do you need if you want an equilibrium concentration of $60\frac gL \ NH_3$ ?

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14. A solution of Lithium Sulfate is being heated. At $80^\circ C$ , Lithium Sulfate is added until it remains as a precipitate in the solution. What would you expect to happen after you take the solution off of heat?

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15. If rain forms at a height where $P=0.52atm$, at a temperature of $8^\circ C$, what will the $CO_2$ concentration be in the raindrop, assuming it spends enough time in the cloud to equilibrate and it doesn’t gain any further $CO_2$ along its descent?

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16. AP edition reviewed standalone replacement.

    Explain why placing copper metal inNaCl solution does not by itself justify the claimed formation of a copper-ion hydrate or a boiling-point prediction from a3g block-mass increase. What reaction and measurement information is missing?

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17. Seawater meets river water at an estuary. The salinity of the seawater begins to infiltrate the river. If the salinity of the water can be shown to be $\left[\text{Salt}\right] = 3.0\cdot\exp\left(-0.0005d\right)$, where $d$ is distance from river mouth in $m$ and $\left[\text{Salt}\right]$ is the concentration of salt as $NaCl$ in $\frac{mol}{kg}$ . At what point up the river will the water freeze if the surface temperature reaches $-1^\circ C$ ?

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18. Carbon dioxide is dissolved into the oceans of the world. If the top $1m$ of our oceans were to increase in average temperature from $17^\circ C$ to $18^\circ C$, what would be the mass of CO2 released? The surface area of the oceans is $361\, 000\, 000km^2$.

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19. When Ammonia gas dissolves in water, it reacts to form Ammonium and Hydroxide ions. If you have 4 atm of ammonia over water at 25ºC and 30% of the dissolved ammonia dissociates, what is the solubility of Ammonium Chloride (ksp = 30.9)?

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20. If a bubbler keeps a fish tank saturated in oxygen, what temperature does the tank need to be kept at to ensure that the concentration is at least 11mg/L?

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