Valeriya Korbina Enthalpy Change Design Practical

Due Date: 05.04.12

Valeriya Korbina

Due Date: 05.04.12

Investigating the Enthalpy Change of different types of alcohol beverages

Research question:

Experiment to investigate the enthalpy change in kJ/mol of combustion of 5 different types of 40% alcohol beverages: Red Label Johnnie Walker Whiskey, Richelieu Cognac, Cointreau liqueur, Molinari Sambuca extra, Tequila Sierra Reposado. 13 ml of each beverage will be burnt at a distance of 3.0 cm between the bottom of the copper cup filled with 200 ml of water and the crucible. Water will be measured with the help of the 250 ml measuring cylinder ( 1.5 ml). Initial and final temperatures will be measured with a Digital Temperature Probe ( 0.1 C) in order to determine the enthalpy change for each type of alcohol. Five trials for each beverage will be taken.

Hypothesis:

I predict that all alcohol beverages will have different heat capacity's and enthalpy changes, because of their's different contents. To my mind some components of the compounds are more flammable, combustible, and can burn more and therefore, the difference in temperature will increase together with an enthalpy change.

Reason:

This experiment is a combustion investigation and all its theory is based on a combustion of the alcohol beverages. Combustion is an exothermic reaction, the heat will be given to the surroundings. Exothermic reactions have to take more energy to break chemical bonds than they need to form bonds. All alcohol beverages contain ethanol (C₂H₅-OH), which is very flammable. All chosen beverages have 40% of it.

Compete combustion of ethanol forms carbon dioxode and water vapor:

C₂H₅-OH (l) + 3O₂ (g) → 2CO₂ (g) + 3H₂O (g)

Diagram 1 Diagram 2

Diagram 1 and 2: showing the full structural formula and a ball-and-stick model

Variables:

Independent variables:

Five different 40% alcohol beverages and brands:

• Red Label Johnnie Walker Whiskey

• Richelieu Cognac

• Cointreau liqueur

• Molinari Sambuca extra

• Tequila Sierra Reposado

Dependent variables:

• Temperature change will be calculated by subtracting the initial temperature from the final temperature.

• Five different enthalpy changes will be calculated by using the formulas including the specific heat capacity of water (4.184 kJ/kgK), temperature change (±0.1 C) and mas of water (200 g, 1.5 mL)

Controlled:

1. Amount of alcohol beverage will be always the same – 13 ml, measured with 25 ml measuring cylinder ( 0.38 ml).

2. Amount of water heated will be always the same – 200 ml, measured with 250 ml measuring cylinder ( 1.5 ml).

3. Distance between the bottom of the copper cup and the ceramic crucible with burning alcohol beverage will be always the same – 3 cm, measured with a ruler ( 0.1 mm).

4. The percentage of ethanol in all alcohol beverages will be the same – 40%.

Apparatus/ Materials:

• Ceramic Crucible

• Safety Goggles

• Clay Triangle

• Clamp stand

• Ring Stand

• Ruler ( 0.1 mm)

• 5 different types of alcohol beverages (40%): Red Label Johnnie Walker Whiskey

Richelieu Cognac

Cointreau liqueur

Molinari Sambuca extra

Tequila Sierra Reposado

• 25 ml Measuring cylinder ( 0.38 ml)

• 250 ml Measuring cylinder ( 1.5 ml)

• Stopwatch ( 0.1 s)

• Water

• 500 ml Copper cup

• Texas TI-84 Plus Calculator

• Vennier Data Logger

• Digital Temperature Probe ( 0.1 C)

• Matches

• Bunsen Burner

• Tongs

• 3 pipettes