a 3.81 g sample of NaHCO3 was completely decomposed. After decomposition, Na2CO3 had mass of 2.86g. Determine mass of H2CO3 prod
1 answer:
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Answer:
- A) pH = 2.42
- B) pH = 12.00
Explanation:
<em>The dissolution of HCl is HCl → H⁺ + Cl⁻</em>
- To solve part A) we need to calculate the concentration of H⁺, to do that we need the moles of H⁺ and the volume.
The problem gives us V=2.5 L, and the moles can be calculated using the molecular weight of HCl, 36.46 g/mol:
= 9.60*10⁻³ mol H⁺
So the concentration of H⁺ is
[H⁺] = 9.60*10⁻³ mol / 2.5 L = 3.84 * 10⁻³ M
pH = -log [H⁺] = -log (3.84 * 10⁻³) = 2.42
- <em>The dissolution of NaOH is NaOH → Na⁺ + OH⁻</em>
- Now we calculate [OH⁻], we already know that V = 2.0 L, and a similar process is used to calculate the moles of OH⁻, keeping in mind the molecular weight of NaOH, 40 g/mol:
= 0.02 mol OH⁻
[OH⁻] = 0.02 mol / 2.0 L = 0.01
pOH = -log [OH⁻] = -log (0.01) = 2.00
With the pOH, we can calculate the pH:
pH + pOH = 14.00
pH + 2.00 = 14.00
pH = 12.00
Answer:
85.8 g
Explanation:
The molar mass of BaCl₂ is 208.233 g/mol, so 210.1 g is about ...
210.1/208.233 ≈ 1.009 mol
The molar mass of K is about 39.089 g/mol, so 45 g is about ...
45/39.089 ≈ 1.1509 mol
The balanced equation seems to be ...
BaCl₂ + 2K ↔ 2KCl + Ba
This reaction requires 2 moles of potassium for each mole of barium chloride, so the available potassium limits the reaction. The result is as many moles of potassium chloride as there are moles of potassium.
The 1.1509 moles of KCl, at 74.551 g/mol will have a mass of about 85.8 g.
The reaction produces 85.8 g of KCl.
