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Chapter 4: Problem 82

A 30.0 -mL sample of an unknown strong base is neutralized after the addition of 12.0 \(\mathrm{mL}\) of a 0.150 \(\mathrm{M} \mathrm{HNO}_{3}\) solution. If the unknown base concentration is 0.0300 M, give some possible identities for the unknown base.

Short Answer

Expert verified
Given a 30.0 mL sample of an unknown 0.0300 M strong base that is neutralized by 12.0 mL of a 0.150 M HNO₃ solution, the possible identities for the unknown base are calcium hydroxide (Ca(OH)₂), strontium hydroxide (Sr(OH)₂), and barium hydroxide (Ba(OH)₂). These bases have the empirical formula M(OH)₂ and are strong bases that can react with HNO₃ to form water and salt.

Step by step solution

01

Calculate the moles of HNO₃

First, we need to calculate the moles of HNO₃ using the given volume and concentration. The formula for this is: Moles of HNO₃ = Volume of HNO₃ × Concentration of HNO₃ Plugging in the given values, we get: Moles of HNO₃ = 12.0 mL × 0.15 M = 1.8 × 10⁻³ mol
02

Calculate the moles of the unknown base

Now, we need to calculate the moles of the unknown base using its given volume and concentration. The formula for this is: Moles of unknown base = Volume of the base × Concentration of the base Plugging in the given values, we get: Moles of unknown base = 30.0 mL × 0.0300 M = 9.0 × 10⁻⁴ mol
03

Calculate the mole ratio between HNO₃ and the unknown base

Since the strong acid and base react with each other in a neutralization reaction, the mole ratio between them must be equal. Therefore, Mole ratio = Moles of HNO₃ / Moles of the unknown base Mole ratio = (1.8 × 10⁻³ mol) / (9.0 × 10⁻⁴ mol) = 2 This means that in the neutralization reaction, 1 mole of the unknown base reacts with 2 moles of HNO₃.
04

Determine the empirical formula of the unknown base

Considering the mole ratio and the fact that the base is strong, the general neutralization reaction can be defined as: Unknown base + 2 HNO₃ → Water + Salt This implies that the unknown base has two replaceable hydroxide (OH⁻) ions. Therefore, the empirical formula of the unknown base is M(OH)₂, where M is the unknown metal cation.
05

Suggest possible identities for the unknown base

Since the empirical formula of the unknown base is M(OH)₂ and it's a strong base, some possible identities for the unknown base include: 1. Calcium hydroxide (Ca(OH)₂) 2. Strontium hydroxide (Sr(OH)₂) 3. Barium hydroxide (Ba(OH)₂) These are strong bases with the empirical formula M(OH)₂.

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Most popular questions from this chapter

Saccharin $\left(\mathrm{C}_{7} \mathrm{H}_{5} \mathrm{NO}_{3} \mathrm{S}\right)$ is sometimes dispensed in tablet form. Ten tablets with a total mass of 0.5894 g were dissolved in water. The saccharin was oxidized to convert all the sulfur to sulfate ion, which was precipitated by adding an excess of barium chloride solution. The mass of BaSO\(_{4}\) obtained was 0.5032 g. What is the average mass of saccharin per tablet? What is the average mass percent of saccharin in the tablets?

A 1.42 -g sample of a pure compound, with formula $\mathrm{M}_{2} \mathrm{SO}_{4}$ was dissolved in water and treated with an excess of aqueous calcium chloride, resulting in the precipitation of all the sulfate ions as calcium sulfate. The precipitate was collected, dried, and found to weigh 1.36 g. Determine the atomic mass of M, and identify M.

What volume of 0.100\(M \mathrm{Na}_{3} \mathrm{PO}_{4}\) is required to precipitate all the lead(II) ions from 150.0 \(\mathrm{mL}\) of 0.250$M \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} ?$

A mixture contains only sodium chloride and potassium chloride. A 0.1586-g sample of the mixture was dissolved in water. It took 22.90 mL of 0.1000 M AgNO3 to completely precipitate all the chloride present. What is the composition (by mass percent) of the mixture?

A stream flows at a rate of \(5.00 \times 10^{4}\) liters per second (L/s) upstream of a manufacturing plant. The plant discharges $3.50 \times 10^{3} \mathrm{L} / \mathrm{s}\( of water that contains 65.0 \)\mathrm{ppm} \mathrm{HCl}$ into the stream. (See Exercise 135 for definitions.) a. Calculate the stream's total flow rate downstream from this plant. b. Calculate the concentration of \(\mathrm{HCl}\) in ppm downstream from this plant. c. Further downstream, another manufacturing plant diverts $1.80 \times 10^{4} \mathrm{L} / \mathrm{s}$ of water from the stream for its own use. This plant must first neutralize the acid and does so by adding lime: $$\mathrm{CaO}(s)+2 \mathrm{H}^{+}(a q) \longrightarrow \mathrm{Ca}^{2+}(a q)+\mathrm{H}_{2} \mathrm{O}(i) $$ What mass of CaO is consumed in an 8.00-h work day by this plant? d. The original stream water contained 10.2 \(\mathrm{ppm} \mathrm{Ca}^{2+}\) . Although no calcium was in the waste water from the first plant, the waste water of the second plant contains \(\mathrm{Ca}^{2+}\) from the neutralization process. If 90.0% of the water used by the second plant is returned to the stream, calculate the concentration of \(\mathrm{Ca}^{2+}\) in ppm downstream of the second plant.
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