There are a number of
ways to express concentration of a solution. This includes molarity. Molarity
is expressed as the number of moles of solute per volume of the solution. The
concentration of the solution is calculated as follows:
<span> </span><span>Molarity = 15.5 g NaOH (1 mol NaOH / 40 g NaOH) / .250 L
solution</span>
<span>Molarity = 1.55 M</span>
Answer is: ph value is 3.56.
Chemical reaction 1: H₂CO₃(aq) ⇄ HCO₃⁻(aq) + H⁺(aq); Ka₁ = 4,3·10⁻⁷.
Chemical reaction 2: HCO₃⁻(aq) ⇄ CO₃²⁻(aq) + H⁺(aq); Ka₂ = 5,6·10⁻¹¹.
c(H₂CO₃) = 0,18 M.
[HCO₃⁻] = [H⁺<span>] = x.
</span>[H₂CO₃] = 0,18 M - x.
Ka₁ = [HCO₃⁻] · [H⁺] / [H₂CO₃].
4,3·10⁻⁷ = x² / (0,18 M -x).
Solve quadratic equation: x = [H⁺] =0,000293 M.
pH = -log[H⁺] = -log(0,000293 M).
pH = 3,56; second Ka do not contributes pH value a lot.
<span>0.38
You first calculate the total moles by dividing the grams by molecular weight:
45 g N2 / 28.02 g/mol = 1.6 mol N2
40 g Ar / 39.95 g/mol = 1.0 mol
Then you divide the moles of Ar by the total number of moles:
1.0 / (1.6 + 1.0) = 0.38 mol fraction</span>
Answer:
4.99 × 10³ g/mol
Explanation:
Step 1: Given and required data
- Mass of the covalent compound (m): 62.4 g
- Volume of the solution (V): 1.000 L
- Osmotic pressure (π): 0.305 atm
- Temperature (T): 25°C = 298 K
Step 2: Calculate the molarity (M) of the solution
The osmotic pressure is a colligative pressure. For a covalent compound, it can be calculated using the following expression.
π = M × R × T
M = π / R × T
M = 0.305 atm / (0.0821 atm.L/mol.K) × 298 K
M = 0.0125 M
Step 3: Calculate the moles of solute (n)
We will use the definition of molarity.
M = n / V
n = M × V
n = 0.0125 mol/L × 1.000 L = 0.0125 mol
Step 4: Calculate the molar mass of the compound
0.0125 moles of the compound weigh 62.4 g. The molar mass is:
62.4 g/0.0125 mol = 4.99 × 10³ g/mol
