Assignment: Enthalpy, Energy, and Temperature Change

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Complete the following thermochemistry problems – show all of your work as you set up equations and make calculations.

    1. The Travis Scott promotional meal at McDonald’s had 1180 Calories (note the capital letter- this indicates nutritional Calories). Find the amount of energy in Joules.
    2. A 9.00 g nugget of pure gold absorbed 276 J of heat. What was the final temperature of the gold if the initial temperature was 25.0° C? The specific heat of gold is 0.129 J/(g °C).
    3. A sample of silver with a mass of 63.3 g is heated to a temperature of 384.4 K and placed in a container of water at 290.0K. The final (equilibrium) temperature of the silver and water is 292.4K. What volume of water is in the container? The specific heat of silver is 0.235 J/(g °C).
    4. NSU Chemistry 101L class conducted an experiment in which a measured amount of NaOH is dissolved in water inside a foam cup calorimeter. A student collected data throughout the experiment. Calculate ΔH for the process in kJ/mol.
      • Data table from the experiment:
        Mass of NaOH + weigh boat 14.13 g
        Mass of weigh boat 0.70 g
        Mass of NaOH
        Mass of foam cup+water 109.85 g
        Mass of foam cup 10.25 g
        Mass of water
        Initial temp of water 24.5°C
        Final temp of water 36.8°C
        Change in temperature (ΔT)
    5. You can light a charcoal grill in about a minute. If the grill is prepared using one 20 pound bag of charcoal (primarily carbon) and two 1 gallon buckets of liquid oxygen (the density of LOX (liquid oxygen) is 1142 kg/m3, CRC Handbook of Chemistry and Physics.)
      • Write a balanced chemical equation describing this reaction.
      • Determine the limiting reagent for this reaction.
      • Calculate the mass of each product and any remaining reactant.
      • Calculate the amount of heat released by this reaction.
      • If this heat is used to warm a 500 gallon tank of water at 15C, what is the final temperature?
      • If this heat is used to warm 40 kg of ice at 200K, what is the final temperature?