SSCE HSC Chemistry Reactions of Metals: Sodium reacts with water to give

Sodium reacts with water to give hydrogen gas and sodium hydroxide solution - HSC - SSCE Chemistry - Question 14 - 2013 - Paper 1

Question 14

Sodium reacts with water to give hydrogen gas and sodium hydroxide solution. What volume of gas would be produced from the reaction of 22.99 g of sodium at 25°C and... show full transcript

Worked Solution & Example Answer:Sodium reacts with water to give hydrogen gas and sodium hydroxide solution - HSC - SSCE Chemistry - Question 14 - 2013 - Paper 1

Step 1

Calculate the moles of sodium (Na)

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Answer

To find the number of moles of sodium, use the molar mass of sodium, which is approximately 22.99 g/mol:

$n = \frac{m}{M} = \frac{22.99\,g}{22.99\,g/mol} = 1\,mol$

Step 2

Determine the volume of hydrogen gas produced

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Answer

From the balanced chemical equation for the reaction of sodium with water:

$2\,Na + 2\,H_2O \rightarrow 2\,NaOH + H_2$

According to the equation, 2 moles of sodium produce 1 mole of hydrogen gas. Therefore, 1 mole of sodium will produce:

$\frac{1}{2} \cdot 1\,mol = 0.5\,mol \, H_2$

Step 3

Apply the Ideal Gas Law to find the volume

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Answer

Using the Ideal Gas Law, which states:

$PV = nRT$

Where:

P is pressure (100 kPa = 100,000 Pa)
V is volume (in m³)
n is the number of moles (0.5 mol)
R is the gas constant (8.314 J/(mol·K))
T is temperature (25°C = 298 K)

Rearranging for V gives:

$V = \frac{nRT}{P} = \frac{0.5\,mol \cdot 8.314\,J/(mol\cdot K) \cdot 298\,K}{100,000\,Pa}$

Calculating this:

$V = \frac{0.5 \cdot 8.314 \cdot 298}{100,000} \approx 0.0124\,m^3$

Converting to liters (1 m³ = 1000 L):

$V \approx 12.40\,L$

Step 4

Select the correct answer from the options

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Answer

The calculated volume of hydrogen gas produced from the reaction is approximately 12.40 L, thus the answer is (B) 12.40 L.

Sodium reacts with water to give hydrogen gas and sodium hydroxide solution - HSC - SSCE Chemistry - Question 14 - 2013 - Paper 1

Worked Solution & Example Answer:Sodium reacts with water to give hydrogen gas and sodium hydroxide solution - HSC - SSCE Chemistry - Question 14 - 2013 - Paper 1

Calculate the moles of sodium (Na)

Determine the volume of hydrogen gas produced

Apply the Ideal Gas Law to find the volume

Select the correct answer from the options

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