Question

Heat Flow and Calorimetry Prelab Questions Section: Name: 1. Prepare for It! Prelab Question A A 235.0 g sample of metal is heated to 100.0C and poured into a calorimeter containing 50.0 g of water at 20.5°c. The equilibrium temperature of the water and metal is 30.5 C. Using the specific heat of water, 4.18 J/goC, determine the specific heat of the metal from equation 3. Use equation 5 to find the approximate molar mass of the metal. Show your work! Use back if needed. 2. Prepare for It! Prelab Question B If 3.1 g of NaOH(s) is dissolved in 57.9 g of water with an initial temperature of 22.5°C and the temperature rises to 36.6°C, then find the enthalpy of solution (in J) using equation 6 Determine the enthalpy in J/g and kJ/mole. Show your work! J/g kJ/mol

Answer 1

1) w represent water and m represents metal

Heat taken by water = heat given by metal

M(w) * S(w) * Delta T(w) = M(m) * S(m) * Delta T(m)

50 * 4.18 * (30.5 - 20.5) = 235 * S * (100 - 30.5)

S = 0.128 J/°C g ....Answer

2)

Heat or enthalpy of solution (H) = m * s * Delta T

H = (3.1+57.9) * 4.18 * (36.6 - 22.5) = 3595.22 J ...Answer

Enthalpy per gram = 3595.22/3.1 = 1159.75 J/g ....Answer

Moles of NaOH = mass/molar mass = 3.1/40 = 0.0775 moles

Thus, enthalpy per mole = 3595.22/0.0775 = 46389.91 J/mol = 46.39 KJ/mol ...Answer

Let me know if any doubts.