Assuming the volumes are additive, what is the \(\left[\mathrm{NO}_{3}^{-}\right]\) in a solution obtained by mixing \(275 \mathrm{mL}\) of \(0.283 \mathrm{M} \mathrm{KNO}_{3}, 328 \mathrm{mL}\) of \(0.421 \mathrm{M} \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2},\) and \(784 \mathrm{mL}\) of \(\mathrm{H}_{2} \mathrm{O} ?\)

Short Answer

Expert verified
Hence, the concentration of nitrate ions \([NO_{3}^{-}]\) in the solution will be \(0.255M\)

Step by step solution

01

Calculate the number of moles of nitrate from potassium nitrate

Number of moles can be calculated using the formula: \(Moles = Molarity \times Volume\). \nSo, for the first solution \(Moles = 0.283 mol/L \times 275 mL × (1 L/1000 mL) = 0.077825 mol\)
02

Calculate the number of moles of nitrate from magnesium nitrate

The same formula will be used for finding the moles in the second solution with small modification, since in each formula unit of magnesium nitrate, there are two nitrate ions - Mg(NO3)2 . Thus: \nMoles = 2 × Molarity × Volume. So, Moles = 2 × 0.421 mol/L × 328 mL × (1 L/1000 mL) = 0.275776 mol.
03

Find the total moles of nitrate

As we have the total moles from step 1 and step 2, we just need to add those: Total nitrate = 0.077825 Mol (from KNO3) + 0.275776 Mol (from Mg(NO3)2) = 0.353601 mol.
04

Calculate the total volume

The total volume of the resultant solution will be the sum of the volumes of its constituents, that is: Total volume = \(275 mL + 328 mL + 784 mL = 1387 mL = 1.387 L\).
05

Find the concentration of nitrate ions

The concentration or molarity can be found out by dividing the total number of moles of nitrate ions by the total volume of the solution. Thus: \([NO_{3}^{-}] = \frac{Total \, moles}{total \, volume} = \frac{0.353601 mol}{1.387 L} = 0.255 M\)

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Most popular questions from this chapter

The highest \(\left[\mathrm{H}^{+}\right]\) will be found in an aqueous solution that is (a) \(0.10 \mathrm{M} \mathrm{HCl} ;\) (b) \(0.10 \mathrm{M} \mathrm{NH}_{3} ;\) (c) \(0.15 \mathrm{M}\) \(\mathrm{CH}_{3} \mathrm{COOH} ;(\mathrm{d}) 0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}\).

Balance these equations for redox reactions occurring in acidic solution. (a) $\mathrm{P}_{4}(\mathrm{s})+\mathrm{NO}_{3}^{-} \longrightarrow \mathrm{H}_{2} \mathrm{PO}_{4}^{-}+\mathrm{NO}(\mathrm{g})$ (b) $\mathrm{S}_{2} \mathrm{O}_{3}^{2-}+\mathrm{MnO}_{4}^{-} \longrightarrow \mathrm{SO}_{4}^{2-}+\mathrm{Mn}^{2+}$ (c) $\mathrm{HS}^{-}+\mathrm{HSO}_{3}^{-} \longrightarrow \mathrm{S}_{2} \mathrm{O}_{3}^{2-}$ (d) $\mathrm{Fe}^{3+}+\mathrm{NH}_{3} \mathrm{OH}^{+} \longrightarrow \mathrm{Fe}^{2+}+\mathrm{N}_{2} \mathrm{O}(\mathrm{g})$

A \(\mathrm{KMnO}_{4}(\) aq) solution is to be standardized by titration against \(\mathrm{As}_{2} \mathrm{O}_{3}(\mathrm{s}) .\) A \(0.1078 \mathrm{g}\) sample of \(\mathrm{As}_{2} \mathrm{O}_{3}\) requires \(22.15 \mathrm{mL}\) of the \(\mathrm{KMnO}_{4}(\) aq) for its titration. What is the molarity of the \(\mathrm{KMnO}_{4}(\) aq)? \(5 \mathrm{As}_{2} \mathrm{O}_{3}+4 \mathrm{MnO}_{4}^{-}+9 \mathrm{H}_{2} \mathrm{O}+12 \mathrm{H}^{+} \longrightarrow\) \(10 \mathrm{H}_{3} \mathrm{AsO}_{4}+4 \mathrm{Mn}^{2+}\)

Following are some laboratory methods occasionally used for the preparation of small quantities of chemicals. Write a balanced equation for each. (a) preparation of \(\mathrm{H}_{2} \mathrm{S}(\mathrm{g}): \mathrm{HCl}(\mathrm{aq})\) is heated with \(\mathrm{FeS}(\mathrm{s})\) (b) preparation of \(\mathrm{Cl}_{2}(\mathrm{g}): \mathrm{HCl}(\mathrm{aq})\) is heated with \(\mathrm{MnO}_{2}(\mathrm{s}) ; \mathrm{MnCl}_{2}(\mathrm{aq})\) and \(\mathrm{H}_{2} \mathrm{O}(1)\) are other products (c) preparation of \(\mathrm{N}_{2}: \mathrm{Br}_{2}\) and \(\mathrm{NH}_{3}\) react in aqueous solution; \(\mathrm{NH}_{4} \mathrm{Br}\) is another product (d) preparation of chlorous acid: an aqueous suspension of solid barium chlorite is treated with dilute \(\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})\)

Every antacid contains one or more ingredients capable of reacting with excess stomach acid (HCl). The essential neutralization products are \(\mathrm{CO}_{2}\) and/ or \(\mathrm{H}_{2} \mathrm{O} .\) Write net ionic equations to represent the neutralizing action of the following popular antacids. (a) Alka-Seltzer (sodium bicarbonate) (b) Tums (calcium carbonate) (c) milk of magnesia (magnesium hydroxide) (d) Maalox (magnesium hydroxide, aluminum hydroxide) (e) Rolaids \(\left[\mathrm{NaAl}(\mathrm{OH})_{2} \mathrm{CO}_{3}\right]\)

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