Experiment: Test the effect of temperature on reaction time

May 18, 2023

Figure 1. In this experiment, we investigate how to make Alka-Seltzer tablets plunked in water fizzle faster and more furiously.

asadykov/iStock/Getty Images Plus

By Science Buddies

July 12, 2023 at 6:30 am

Objective: To measure the effect of temperature on the rate of a chemical reaction

Areas of science: Chemistry, science with your smartphone

Difficulty: Easy intermediate

Time required: 2–5 days

Prerequisites: None

Material availability: Readily available

Cost: Very low (under $20)

Safety: Adult supervision may be needed when working with hot water solutions

Credits: Andrew Olson, PhD, Science Buddies; edited by Svenja Lohner, PhD, Science Buddies

You may have seen a television commercial for Alka-Seltzer tablets or heard one of their advertising slogans: “Plop, plop, fizz, fizz, oh what a relief it is!” When you drop the tablets in water, they make a lot of bubbles, like an extra-fizzy soda, as shown in the main image up top (Figure 1). And like a soda, the bubbles are carbon dioxide gas (CO2). However, with Alka-Seltzer, the CO2 is produced by a chemical reaction that occurs when the tablets dissolve in water.

Alka-Seltzer is a medical drug that works as a pain reliever and an antacid (antacids help neutralize stomach acidity, such as heartburn). The pain reliever used is aspirin and the antacid used is baking soda (sodium bicarbonate, NaHCO3). To take the tablets, they should be fully dissolved in a glass of water. When sodium bicarbonate dissolves in water, it dissociates (splits apart) into sodium (Na+) and bicarbonate (HCO3) ions. (An ion is a molecule that has a charge, either positive or negative.) The bicarbonate reacts with hydrogen ions (H+) from citric acid (another ingredient in the tablets) to form carbon dioxide gas and water. In other words, carbon dioxide gas is a product of this reaction. The reaction is described by Equation 1 below:

Equation 1.3HCO3− + 3H+ → 3H2O + 3CO2

So how is temperature related to this bicarbonate reaction? In order for the reaction shown above to occur, the bicarbonate ions have to come into contact with the hydrogen ions. Molecules in a solution are in constant motion and are constantly colliding with one another. The hydrogen and bicarbonate ions must collide at the right angle and with enough energy for the reaction to occur. The temperature of a solution is a measure of the average motion (kinetic energy) of the molecules in the solution. The higher the temperature, the faster the molecules are moving. What effect do you think temperature will have on the speed, or rate, of the bicarbonate reaction?

In this chemistry science project, you will find out for yourself by plopping Alka-Seltzer tablets into water at different temperatures and measuring how long it takes for the chemical reaction to go to completion. In addition, you can record the sound of the Alka-Seltzer fizzle using a smartphone equipped with a sensor app. Do you think it will fizz more loudly in hot or cold water?

Note: In this science project, you will investigate how water temperature affects the dissolving time of an Alka-Seltzer tablet. You will use a smartphone equipped with a sensor app to record the fizzing sound of the Alka-Seltzer reaction in water and measure the time it takes for one Alka-Seltzer tablet to react completely in water. The app creates a graph that will not only give you information about the reaction time but will also allow you to assess how loud each reaction was based on the measured sound intensities. If you do not have a phone, you can observe the reaction and use a stopwatch to time how long it takes for each tablet to dissolve.

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This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

amplitude: A measure of the height of a recurring wave in some signal, water or beam of radiation. In sound, wave amplitude corresponds with intensity — loudness or softness.

angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

antacid: A medicine used to neutralize the acid in the stomach.

app: Short for application, or a computer program designed for a specific task.

aspirin: A common non-prescription drug, also known as acetylsalicylic acid. For more than a century, it has been widely used to treat headaches, joint pain, muscle pain, toothaches and more. It also reduces fevers and inflammation. Ancient papyrus texts indicate that as long as 5,000 years ago, the Sumerians and Egyptians were using willow bark (the source of aspirin’s active ingredient) to treat aches and pains.

audio: Having to do with sound.

average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

carbon: A chemical element that is the physical basis of all life on Earth. Carbon exists freely as graphite and diamond. It is an important part of coal, limestone and petroleum, and is capable of self-bonding, chemically, to form an enormous number of chemically, biologically and commercially important molecules.

carbon dioxide: (or CO2) A colorless, odorless gas produced by all animals when the oxygen they inhale reacts with the carbon-rich foods that they’ve eaten. Carbon dioxide also is released when organic matter burns (including fossil fuels like oil or gas). Carbon dioxide acts as a greenhouse gas, trapping heat in Earth’s atmosphere. Plants convert carbon dioxide into oxygen during photosynthesis, the process they use to make their own food.

constant: Continuous or uninterrupted.

data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

decibel: A measurement scale used for the intensity of sounds that can be picked up by the human ear. It starts at zero decibels (dB), a sound hardly audible to people with good hearing. A sound 10 times louder would be 10 dB. Because the scale is logarithmic, a sound 100 times louder than 0 dB would be 20 dB; one that’s 1,000 times louder than 0 dB would be described as 30 dB.

degree: (in geometry) A unit of measurement for angles. Each degree equals one three-hundred-and-sixtieth of the circumference of a circle.

dissolve: To turn a solid into a liquid and disperse it into that starting liquid. (For instance, sugar or salt crystals, which are solids, will dissolve into water. Now the crystals are gone and the solution is a fully dispersed mix of the liquid form of the sugar or salt in water.)

equation: In mathematics, the statement that two quantities are equal. In geometry, equations are often used to determine the shape of a curve or surface.

error: (In statistics) The non-deterministic (random) part of the relationship between two or more variables.

error bar: A line (it can be vertical or horizontal) drawn through a point or a bar on a graph. The distance from one end of the line to the other represents how precise a measurement is, or how far the real value of something might fall from the data point reported in the experiment.

factor: Something that plays a role in a particular condition or event; a contributor.

function: The specific role some structure or device plays. (in math) A relationship between two or more variables in which one variable (the dependent one) is exactly determined by the value of the other variables.

glass: A hard, brittle substance made from silica, a mineral found in sand. Glass usually is transparent and fairly inert (chemically nonreactive). Aquatic organisms called diatoms build their shells of it.

hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless and highly flammable. It’s an integral part of many fuels, fats and chemicals that make up living tissues. It’s made of a single proton (which serves as its nucleus) orbited by a single electron.

ion: (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.

kinetic energy: The energy held by an object due to its being in motion. The amount of this energy contained will depend on both the mass (usually weight) of the object and its speed.

liquid: A material that flows freely but keeps a constant volume, like water or oil.

molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).

particle: A minute amount of something.

plastic: Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation. (adj.) A material that is able to adapt by changing shape or possibly even changing its function.

point: (in mathematics) A precise point in space that is so small that it has no size. It merely has an address.

range: The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which values can vary (such as the highest to lowest temperatures). Also, the distance within which something can be reached or perceived.

right angle: A 90-degree angle, equivalent to any inside corner on a square.

sensor: A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly.

smartphone: A cell (or mobile) phone that can perform a host of functions, including search for information on the internet.

sodium: A soft, silvery metallic element that will interact explosively when added to water. It is also a basic building block of table salt (a molecule of which consists of one atom of sodium and one atom of chlorine: NaCl). It is also found in sea salt.

sodium bicarbonate: Also known as baking soda, this white, chemical powder occurs naturally. Its formula is NaHCO 3 . It also has been used as a natural product to extinguish small electrical and grease fires. When ingested, it can help settle acid stomachs. Indeed, it is the main ingredient of many antacids sold in grocery stores.

solid: Firm and stable in shape; not liquid or gaseous.

solution: A liquid in which one chemical has been dissolved into another.

standard deviation: (in statistics) The amount that each a set of data varies from the mean.

tool: An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.

vertical: A term for the direction of a line or plane that runs up and down, as the vertical post for a streetlight does. It’s the opposite of horizontal, which would run parallel to the ground.

Website:​ Bayer HealthCare, LLC. (2005.). Experiment 1: The Effects of Temperature on Rate. Retrieved July 3, 2013.

Book: Swanson, G.C. (n.d.). Chemistry Experiments for the Home: Bubble Rate. Science Department, Daytona Beach Community College.

Website: Brown, W.P. (2007). GCSE Notes on the Rates of Chemical Reactions. Retrieved February 24, 2010.

Website: Clark, J. (2002). Understanding Chemistry: Rates of Reaction Menu. Retrieved May 11, 2007.

Website: Helmenstine, A.M. (2007). Understanding Endothermic and Exothermic Reactions. Retrieved July 14, 2020.

Website: Rader's Chem4Kids.com. (n.d.). Chemical Reactions. Retrieved July 14, 2020.

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Readability Score: 8.3