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Calorimetry Worksheet 2 Answers Chemsheets

Typical problem: 50.0 cm³ of 1.0 M HCl and 50.0 cm³ of 1.0 M NaOH are mixed in a styrofoam cup. Initial temperature of both = 20.0°C. Final temperature = 26.5°C. Calculate the enthalpy of neutralization (kJ/mol). Density of solution = 1.00 g/cm³, c = 4.18 J/g°C.

Step-by-step answer:

  • Moles of water formed:
  • ΔH per mole:

    • Answer: Enthalpy of neutralization = -54.3 kJ/mol (accepted value ≈ -57 kJ/mol, slight difference due to heat loss).

    Let’s be real—calorimetry can feel like a juggling act. One minute you’re calculating temperature changes (ΔT), the next you’re wrestling with specific heat capacity (c), and just when you think you’re done, someone throws in q = mcΔT for the third time just to be sure. calorimetry worksheet 2 answers chemsheets

    If you’ve just finished Chemsheets Calorimetry Worksheet 2 and want to check your work—or you’re completely stuck and need a nudge in the right direction—you’re in the right place.

    A quick heads-up: I can’t republish the entire copyrighted worksheet here, but I can give you the final answers, the key equations, and walk through the most common problem types so you can see where your numbers went right (or wrong).

    Problem: When 0.5 g of magnesium is added to 100 mL of 1 M HCl, the temperature of the solution increases from 22.0°C to 28.0°C. Calculate the enthalpy change for the reaction. Typical problem: 50

    Assumptions: Specific heat capacity of solution = 4.18 J/g°C, density of solution ≈ 1 g/mL.

    Solution:

    This value represents the heat released to the surroundings. To find the (\Delta H) per mole of magnesium reacted, we need the number of moles of magnesium: (0.5 , \textg / 24.3 , \textg/mol = 0.0206 , \textmol) Moles of water formed:

    (\Delta H = -2.508 , \textkJ / 0.0206 , \textmol = -121.7 , \textkJ/mol)

    You’ll often get an answer in Joules first. Convert to kJ (÷1000), then divide by moles of reactant to get kJ/mol.

    Using the formula Q = mcΔT, we substitute the given values: m = 50g, c = 4.18 J/g°C, and ΔT = 30°C - 20°C = 10°C. Therefore, Q = 50g * 4.18 J/g°C * 10°C = 2090 J.

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