Question

Calculate the work done when 1.0 ml of 6.0 m hcl(aq) is placed on a block of limestone, caco3 (s) and allowed to react completely at 1 bar and 25 degrees
c. assume the volume of the liquids and solids participating in the reaction are negligible

Answer 1

Answer:

The system does 7.4 J of work on the surroundings.

Explanation:

Step 1. Write the chemical equation

2HCl(aq) + CaCO₃(s) ⟶ CaCl₂(aq) + H₂O(ℓ) + CO₂(g)

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Step 2. Calculate the moles of HCl.

n = cV

c = 6.0 mol/L

V = 1.0 mL = 0.0010 L              Calculate the moles of HCl

Moles of HCl = 0.0010 × 6.0/1

Moles of HCl = 0.0060 mol

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Step 3. Calculate the moles of CO₂

The molar ratio is 1 mol CO₂:2 mol HCl

Moles of CO₂ = 0.0060 × ½

Moles of CO₂ = 0.0030 mol CO₂

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Step 4. Calculate the volume of CO₂

We can use the Ideal Gas Law

pV =nRT                                          Divide both sides by p

V =(nRT)/p

R = 0.083 14 bar·L·K⁻¹mol⁻¹

T = (25 + 273.15) K = 298.15 K

p = 1 bar                                           Calculate the volume

V = (0.0030× 0.083 14 × 298.15)/1

V = 0.074 L

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Step 5. Calculate the work done.

w = -pΔV

ΔV = V₂ - V₁ = 0.074 L – 0 = 0.074 L     Calculate the work done

w = -1 × 0.074

w = -0.074 bar·L                                      Convert to joules

1 bar·L = 100 J

w = -0.074× 100/1

w = -7.4 J