Answer:
3.
Explanation:
- Al(OH)₃ reacts with HCl to produce AlCl₃ and water according to the balanced equation:
<em>Al(OH)₃ + 3 HCl → AlCl₃ + 3H₂O,</em>
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<em>It is clear that 1.0 mole of Al(OH)₃ reacts with 3.0 mole of HCl to produce 1.0 mole of AlCl₃ and 3.0 moles of H₂O,</em>
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<em>So, the coefficient of HCl is 3.</em>
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The formula here is:
pH = -log[H+]
3.6 = -log[H+]
[H+] = 2.51 x 10⁻⁴ mol / Liter
The first option is correct.
Adding carbon (12g) and oxygen (16g) you get 28g
First let us calculate the moles of K2Cr2O7 that was
supplied.
moles K2Cr2O7 = 0.0010 M * 0.0083 L = 8.3x10^-6 mol
From the chemical formula itself, we see that there are 7
O for every mole of K2Cr2O7 or 3.5 O2. Therefore:
moles O2 = 8.3x10^-6 mol K2Cr2O7 * (3.5 mol O2 / 1 mol K2Cr2O7)
moles O2 = 2.905x10^-5 mol O2
Calculating for the mass of O2 in mg:
mass O2 = 2.905x10^-5 mol O2 * (32 g / mol) * (1000 mg /
g)
mass O2 = 0.9296 mg
Therefore the chemical oxygen demand (COD) is:
COD = 0.9296 mg / (0.025 L)
<span>COD = 37.184 mg/L</span>