Reaction Rates and Effects of Temperature, Concentration, and Surface Area

Introduction

When an acid and a base are reacted, a neutralization reaction occurs whereby a solution and a gas are formed. This experiment tests the effect of temperature, concentration, and surface area on the rate of reaction. Temperature is defined as the degree of hotness or coldness of a substance, measured in degrees Celsius (Flowers et al., 2019). Concentration is a measure of the amount of a solute in a solution, which is expressed in Kilograms per liter (Kg/l). In reference to chemical elements, surface area describes the exposed area of a substance that can take part in a chemical reaction (Flowers et al., 2019). The temperature of reactants, the concentration of a substance, and the surface area are directly proportional to the rate of reaction.

The collision theory is a mathematical model for predicting the speeds of chemical reactions, especially in gases. The collision theory assumes that in order for a reaction to occur, the interacting species must collide with each other (Flowers et al., 2019). In reference to temperature, the increase in temperature raises the kinetic energy, thereby increasing the rate of collisions. The higher the concentration, the more the number of particles and, therefore, the higher the rate of collisions. According to the collision theory, increasing the surface area increases the surfaces available for collisions, increasing the rate of reaction (Flowers et al., 2019). In essence, the theory proposes that an increase in reacting elements, surfaces, and kinetic energy translates to more collisions and consequently faster reactions.

Hypothesis

The reaction between calcium carbonate and dilute hydrochloric acid results in the production of calcium chloride solution, carbon dioxide gas, and water, as shown in the equation below. Under normal temperature, an increase in concentration and surface area will increase the rate of reaction (Flowers et al., 2019). Concentration will be determined by how much of the 350 g of CaCO3 is dissolved in water. As the solution is heated, the rate of reaction increases, given by the equation below.

CaCO₃ + 2 HCl → CaCl₂ + CO₂ + H₂O.

Procedure

1. Measure 50 g of CaCO₃ in a water jar with 100 ml water and stir completely.
2. Add HCl in a titration tube.
3. Slowly titrate the solution while measuring the volume of gas produced every 5 minutes in a gas jar.
4. Repeat part 1 and heat the war the solution.
5. Titrate and measure the new volumes of gas.
6. Now mix 100 g of CaCO₃ as in step 1 above.
7. Titrate and measure the volume of gas.
8. Take 50 g of CaCO₃ and crush them.
9. Repeat steps 2 and 3.

Data Tables

Relating Result to Scenarios

Crushed ice has a larger surface area than ice cubes, which increases the area exposed to collisions and reactions. Therefore, crushed ice will cool a soda faster than ice cubes, according to the collision theory. In hot tea, sugar would dissolve faster than in iced due to faster collisions in high temperatures. Lastly, a strong powdered milk concentration would be easier to taste because of the increased number of particles which increase the probability of collisions and, therefore, being tasted.

Conclusion

This lab was designed to test the effects of temperature, concentration, and surface area on the rate of reaction. The reactants used were CaCO₃ and dilute hydrochloric acid. The lab was set to generate four data sets: under normal temperature and low concentration, higher temperature, higher concentration, and increased surface area. The results imply an increase in temperature, surface area, and concentration increases the rate of reaction. This relates to the collision theory, which proposes that an increase in the rate of collisions leads to faster reactions.

Reference

Flowers, P., Theopold, K., Langley, R., Neth, E. J., & Robinson, W. R. (2019). Chemistry (2nd ed.). Openstax.