Experiment One: Specific Heat of Metal

Experiment One: The Specific Heat of Metal

• Calorimetry is the measurement of heat flow into or out of a system
• Heat flow is measured using a device called a calorimeter.
• An ideal calorimeter insulates the substance to prevent heat loss to surroundings.
• When heat flows into or out of a substance, its temperature changes.
• Specific heat capacity is the amount of heat energy required to raise the temperature of one gram of a substance by one degree Celsius.
• Water has a specific heat capacity of 4.184 J/g.°C.
• The mathematical relationship relating heat flow (q), mass (m), temperature change (ΔT), and specific heat capacity (c) is: q = m * c * ΔT
• In this experiment, the specific heat of a metal is determined.
• A heated metal sample is placed in a calorimeter containing cool water.
• The metal and water reach the same temperature.
• Heat lost by the metal equals heat gained by the water.
• Heat gained by the water is calculated using the formula: heat gained_water = specific heat_water * mass_water * ΔT_water
• Heat lost by the metal is calculated using a similar formula: heat lost_metal = specific heat_metal * mass_metal * ΔT_metal
• The heat gained must equal the heat lost: specific heat_water * mass_water * ΔT_water = - specific heat_metal * mass_metal * ΔT_metal
• The negative sign indicates heat exchange. The metal loses heat while the water gains heat

Experiment 2: Enthalpy of Formation of Magnesium Oxide

• Calorimetry is a technique used to measure primary thermodynamic data.
• Every calorimeter has a unique heat capacity (C_cal) that must be determined.
• Hess's Law states that the enthalpy change of a reaction is the same whether it occurs in one step or multiple steps.
• Enthalpy change (ΔH) of a chemical reaction is the amount of heat gained or lost by the reaction.
• Standard (molar) enthalpy of formation (ΔH_f) is the ΔH when one mole of a compound is formed from its elements in their reference form and standard states.
• Enthalpy is a state function, meaning its change depends only on the initial and final states, not the path taken.
• This experiment measures the enthalpy of formation of magnesium oxide (MgO) using calorimetry and Hess's Law.

Experiment 4 Determining Heat of Solution by Solubility Method

• Solubility of a solid in a liquid is temperature-dependent.
• At a given temperature, only a certain maximum amount of solute will dissolve in a given amount of solvent (saturated solution).
• Excess solute remains as a solid.
• A saturated solution can contain more solute than normally held in equilibrium with the solid state (supersaturated).
• Heat is evolved or absorbed when a substance dissolves in a solvent—this change is temperature-dependent.
• Vant' Hoff Equation calculates heat of solution with the equation ΔHf = -R*[(ln s2/s1) / (1/T2- 1/T1)]

Experiment 2: Molar Mass of a Solid from Freezing Point Depression

• The vapor pressure of a pure liquid is a characteristic property.
• Dissolving a non-volatile solute in a liquid lowers the vapor pressure.
• Colligative properties depend on the number of solute particles and not their nature.
• The freezing point of a solution is lower than the freezing point of a pure solvent (freezing point depression)
• The change in freezing point is directly related to the concentration of the solute (molality).
• This experiment determines the molar mass of an unknown solute by measuring its freezing point depression Using the freezing point depression of cyclohexane, the molar mass is calculated.

This quiz covers Experiment One, focusing on the specific heat of metals and the principles of calorimetry. You will learn about heat flow, the calorimeter's role, and the calculations necessary to determine the specific heat capacity of a substance. Understanding these concepts is crucial for anyone involved in physical sciences or engineering.