Chemistry SL Internal Assessment: Enthalpy Change Design Lab Experiment: Reaction of distilled water and solid sodium hydroxide RESEARCH QUESTION
How does the heat released during the reaction between distilled water and Group 1 elements (lithium, sodium and potassium) vary as one goes down the group? OBJECTIVE
The objective of the experiment is to measure the heat change during the reactions with minimal heat loss to the surroundings. MATERIALS
The materials to be used in this experiment are:
Lithium, sodium, and potassium metal are the three Group 1 elements and reactants. •
Distilled water is a reactant.
250ml beaker to measure the water.
Polystyrene cup to hold the water.
Knife to cut the metals.
Digital balance to measure the mass of the metals.
Calorimeter to trap the heat during the reactions.
Thermometer to measure the initial and final temperatures during the reaction. •
Paper and pencil to record data such as masses and temperatures. •
Lab coat and goggles for safety.
Independent: Type of substance
The mass of the substance is the control variable, since there is a fixed amount of substance being used in the reaction to control the rate of reaction. UNCERTAINTIES
Temperature: There is an uncertainty of ± 0.1 oC since the calorimeter is not closed at all times and there can be inaccuracies in the thermometer. •
Mass: There is an uncertainty of ± 0.1 g due to inaccuracy of the digital balance. PROCEDURE
Cut out a small piece of lithium metal.
Measure about 2g of lithium on a digital balance and place it in a beaker. •
Measure about 100 ml (100 g) of distilled water in a 250 ml beaker. •
Use a thermometer to measure the temperature of the water. •
Pour the water into a polystyrene cup and place it in a calorimeter. •
Add lithium to the water.
Allow the reaction to occur and then measure the temperature.
Cut out a small piece of...
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