CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle. The pressure of CO₂ above the water was raised to 3.00 atm and the gaseous CO₂ came to equilibrium with the CO₂ dissolved in the water. At equilibrium, the mass of CO₂ dissolved in the water was 5.00 g. a. The equilibrium constant for this reaction, in atm M⁻¹, can be written as: $$K_{eq} = \frac{p(CO_2, \ g)}{[CO_2(aq)]}$$ where $p(CO_2)$ represents the pressure of CO₂. Calculate the value of this equilibrium constant at 25°C.

SSCE VCE Chemistry Rates of Chemical Reactions: CO₂ is added to 1.00 L of pure w

CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle - VCE - SSCE Chemistry - Question 6 - 2004 - Paper 1

Question 6

CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle. The pressure of CO₂ above the water was raised to 3.00 atm and the gaseous CO₂ came to equilibr... show full transcript

Worked Solution & Example Answer:CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle - VCE - SSCE Chemistry - Question 6 - 2004 - Paper 1

Step 1

Calculate the number of moles of CO₂

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Answer

To find the number of moles of CO₂ dissolved, we use the formula:

$n(CO_2) = \frac{mass}{molar \\ mass}$

The molar mass of CO₂ is 44.01 g/mol:

$n(CO_2) = \frac{5.00 \, g}{44.01 \, g/mol} \approx 0.1136 \, mol$

Step 2

Calculate the concentration of CO₂ in the solution

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Answer

The concentration of CO₂ in the 1.00 L of solution is given by:

$[CO_2(aq)] = \frac{n(CO_2)}{volume} = \frac{0.1136 \, mol}{1.00 \, L} = 0.1136 \, M$

Step 3

Calculate the pressure of CO₂ using the ideal gas law

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Answer

Using the ideal gas law, we can find the pressure:

$p(CO_2) = \frac{nRT}{V}$

Where $R = 0.0821 \, L \, atm \, K^{-1} \, mol^{-1}$ , $T = 273 + 25 = 298 \, K$ , and $V = 1.00 \, L$ :

$p(CO_2) = \frac{0.1136 \, mol \times 0.0821 \, L \ atm \, K^{-1} \, mol^{-1} \times 298 \ K}{1.00 \, L} \approx 2.78 \ atm$

Step 4

Calculate the equilibrium constant K_eq

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Answer

Now, we can use the values obtained to calculate the equilibrium constant:

$K_{eq} = \frac{p(CO_2, \ g)}{[CO_2(aq)]} = \frac{3.00 \, atm}{0.1136 \, M} \approx 26.4 \, atm \ M^{-1}$

CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle - VCE - SSCE Chemistry - Question 6 - 2004 - Paper 1

Worked Solution & Example Answer:CO₂ is added to 1.00 L of pure water at 25°C in a pressurised bottle - VCE - SSCE Chemistry - Question 6 - 2004 - Paper 1

Calculate the number of moles of CO₂

Calculate the concentration of CO₂ in the solution

Calculate the pressure of CO₂ using the ideal gas law

Calculate the equilibrium constant K_eq

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