Chemistry 12 Lab: Alka Seltzer Lab (Reaction Rates of a Reaction)
1. Obtain a digital mass balance. Turn on. Obtain a thermometer.
2. Obtain a small beaker and fill 1/3 to ½ full with tap water. Add a few pieces of ice from a
crushed ice cube or crushed ice chunk.
3. Make a chart to record mass readings for every 10s time interval as shown: Note you will need
to make 4 of these charts.
Time (10 s intervals)
1
2
3
4
5
6
Etc.
4.
5.
6.
7.
8.
9.
10.
Digital Scale Mass Reading
Dry the beaker on the outside if any water droplets have accumulated there. Also make sure
the digital balance does not have water drops on the balance pan.
Stir the water in the beaker until it reaches a temperature of from 0-4 degrees Celsius.
When the water/ice mixture has reached a temperature of 0-4 Celsius, remove the ice. Again
check that the outside of the beaker is dry and dry it if any water drops have accumulated.
Record the temperature and quickly move the beaker onto the mass balance to prevent it from
heating up too much before the alka seltzer is added.
Use the TARE button to zero the mass balance. Quickly add an alka seltzer tablet to the beaker
and record the first stable mass reading. Continue to record mass readings every 10s time
interval until the alka seltzer tablet stops fizzing.
Prepare a second setup identical to the first but with water at a temperature that is 10 degrees
higher than the first experiment (0-4 celsius on the first experiment). To do this, fill the beaker
½ to 1/3 with tap water and add ice pieces until the water reaches the temp of 10-14 celsius –
10 celsius warmer than the first experiment. Again make sure that the beaker and digital
balance do not have water drops on them. Rec ord the mass readings every 5 seconds rather
than 10 seconds since the reaction will proceed faster.
Prepare a third setup identical to the first but with water at a temperature that is 20 degrees
higher than the first experiment (0-4 celsius on the first experiment). To do this, fill the beaker
½ to 1/3 with tap water and add warm water from the hot water taps to get the correct
temperature (The taps with red discs on the knobs are hot water taps. Let water run from the
hot water taps for a while since it takes time for hot water to get to the lab from the hot water
tank). Again make sure that the beaker and digital balance do not have water drops on them.
Rec ord the mass readings every 5 seconds rather than 10 seconds since the reaction will
proceed faster.
Prepare a fourth setup identical to the first but with water at a temperature that is 30 degrees
higher than the first experiment (0-4 celsius on the first experiment). To do this, fill the beaker
Chemistry 12 Lab: Alka Seltzer Lab (Reaction Rates of a Reaction)
½ to 1/3 with warm water from the hot water taps to get the correct temperature (The taps
with red discs on the knobs are hot water taps. Let water run from the hot water taps for a
while since it takes time for hot water to get to the lab from the hot water tank). Again make
sure that the beaker and digital balance do not have water drops on them. Rec ord the mass
readings every 5 seconds rather than 10 seconds since the reaction will proceed faster.
Lab Write-up:
1. Use an excel spreadsheet to calculate the mass of CO2 produced every time interval for the first
experiment at 0-4 degrees Celsius. Left sample shows some made-up values, right sample
shows formulas used to get these values.
Time
Interval
Mass Recorded
CO2
Made
1
5.43
0
2
5.11
0.32
3
4.89
0.54
4
4.56
0.87
etc
Time Interval
Mass Recorded
CO2 Made
1
5.43
=$B$2-B2
2
5.11
=$B$2-B3
3
4.89
=$B$2-B4
4
4.56
=$B$2-B5
etc
etc
Etc
2. Load the Logger Pro program. Input the time intervals as x values and the mass values as y
values. Give the graph a title and label the axes : x axis is time (10s intervals) and y axis is mass
CO2. The title is the mass of CO2 produced with increasing time at ___ Celsius (your
temperature). Select the part of the graph that is a straight line and do a regression line or
trend line for this part of the graph. (A regression line is the slope of a line for the selected
section of the graph.) Recall that the slope of the straight line part of this graph represents the
reaction rate for this reaction in terms of CO2 produced per s. Copy the logger pro graph to a
separate word document.
3. Make a second graph on logger pro as before with the following changes: The title will be the
same but with a different temperature. The x axis label will be time (5s intervals). Again find
the slope of the nearly straight section of the graph and find its slope using Logger Pro. Copy
the graph to a separate word page.
4. Make a third and fourth graph based on the data from experiment three and four (temperatures
at 20+ and 30+ your first temperature.
Lab Format:
Title
Chemistry 12 Lab: Alka Seltzer Lab (Reaction Rates of a Reaction)
Purpose (Write a simple description of what you are investigating – relation of reaction rate to
temperature and the 10 celsius increase rule) (In past tense)
Procedure – a brief description of what you did (in past tense)
Data and calculations – Excel spreadsheets
Graphs – Logger Pro graphs or excel graphs
Conclusions/Sources of Error – What do your data show. Address the 10 celsius pattern in relation to
your data. Indicate the evidences of errors in your data and why these errors exist.