Effect of Surface Area on the Rate of the Reaction Between Calcium Carbonate and Hydrochloric Acid

1.0  Title

Investigating the effect of surface area on the rate of the reaction between calcium carbonate and hydrochloric acid in an experiment.

2.0  Research Question

How does the surface area affect the rate of the reaction of Calcium Carbonate in a powdered and chip form?

3.0  Rationale

This experiment will focus on how the surface area effects the rate of reaction between calcium carbonate and hydrochloric acid.

The rate of a chemical reaction, depends on a variety of factors. These include temperature, concentration, surface area and the presence of a catalyst.

Each reaction proceeds at its own speed. Some reactions are naturally faster or slower than others. However, the rate of a chemical reaction depends on a variety of factors. These include temperature, concentration, surface area and catalyst. almost any reaction can be modified in several ways. Collision theory helps to explain why this rate changes occur. Collision theory states that the rate of a chemical reaction is proportional to the number of collisions between reactant molecules. (

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This experiment will focus on surface area.) The effect of these factors on reaction rate can be explained by collision theory. Collision theory states that the rate of a chemical reaction is proportional to the number of collisions between reactant molecules. The more often reactant molecules collide, the more often they react with one another, and the faster the reaction rate. (BBC, 2014)

By raising the temperature, the reaction rate increases. By lowering the temperature, the reaction rate decreases. This is because at higher temperatures the motions of the reactant particles are more energetic than at lower temperatures, which also means that the particles will have enough energy to collide to form products. Lowering the temp. would have the opposite effect. Therefore, at higher temperatures the reaction rate increases, while at lower decreases. Increasing the concentration of reactants increases the number of reacting particles in a given volume that affects the rate at which reactions occur. Cramming more particles into a fixed volume increases collision frequency. Therefore, increasing the concentration of reactants increases the reaction rate. The reaction rate can also be increased by increasing the catalyst. A catalyst is a substance that increases the rate of a reaction without being used up itself in the reaction. It reduces the amount of energy that the reactant particles need to collide with and be converted into products. Because they need less energy, the reactants will be converted into products faster and so the reaction rate increases. (ChemistryLibreTexts, 2017) An increase in catalyst is not always the best way to increase the rate of a reaction. The reaction rate can also be increased, by increasing the surface area. To increase the surface area the material needs to be crushed into a powder. For less surface area the material needs to stay in a solid form.

But, the purpose of conducting this experiment was to determine the effect of surface area on the rate of reaction between calcium carbonate and hydrochloric acid. The prediction was that the reaction rate between calcium carbonate and Hydrochloric acid will be different because of a different surface area. It is well established that the larger the surface area the greater the reaction rate, this is because more surface area particles of the CaCo3 will be exposed to the dilute hydrochloric acid, so there would be more frequent and successful collisions, increasing the rate of reaction. Decreasing the surface area would have and opposite effect.

Formula used for this experiment included the following products: calcium carbonate chips (CaCo3), calcium carbonate powder (CaCo3), hydrochloric acid (HCl), a salt calcium carbonate (CaCl2), carbon dioxide (CO2) and water (H2O)

Equation 1:  CaCO3 + HCl         CaCl2 + CO2 + H2O

3.1 Aim

To investigate the effect of surface area on the rate of the reaction between chips, powder and hydrochloric acid, and to determine if a larger surface area has a faster reaction rate then a smaller surface area.

3.2  Variables

Independent variable: The independent variable within this experiment was the surface area of calcium carbonate. This was changed by using a large and a small surface area. 

Dependent variable: The dependent variable in this experiment was the time taken (sec) for the calcium carbonate to react with the hydrochloric acid.

Controlled variable: The variables that were controlled in this experiment were the mass of Calcium carbonate and the volume of hydrochloric acid (1ML) These were controlled by using the same amount of Calcium Carbonate and Hydrochloric acid throughout the experiment.

3.3 Hypothesis

It is predicted that when the surface area is increased the reaction rate between calcium carbonate and hydrochloric acid will speed up. But if the surface area decreased then the reaction rate will slow down because, with an increase of surface area there are more atoms to react with compared to a smaller surface area.

4.0 Equipment list

In order to complete this experiment, the following materials were required:

• Hydrochloric acid (1ML)
• Marble chips (5g)
• Powder (5g) 
• Stopwatch
• Conical Flask
• Scales
• Spatula
• Measuring cylinder
• Beaker (250 ml)
• Gloves
• Apron
• Goggles
• Thermometer
• Weight boat

4.1 Methodology

The equipment was set up as shown in the diagram above

3.1 Place a weight boat on the scale and tare it. Weigh 5g of caco3 chips and remove the weight boat from the scales

3.2 Place a 250ml beaker on the scales. Using the measuring cylinder, measure 50ml of 1M HCL and pour into the beaker. Zero the scales. (when adding Hydrochloric acid to the beakers, make sure eyes are at the same level of the beaker to make an accurate measurement.)

3.3 Place the thermometer into the beaker and tare it.

3.4 Pour the 5g of CaCo3 chips into the beaker and immediately start the timer. (make sure Calcium Carbonate is placed in a beaker with care)

3.5 Every 20 sec. record the weight and temperature results in a table until the time exceeds to 5 min.

3.6 Repeat steps 1-5 using the CaCo3 chips

3.7 Repeat steps 1-5 using the CaCo3 powder.

3.8 The data was recorded, tabulated and graphed.

3.9 When the experiment is completely finished, all chemicals need to be tipped into the sink. All of equipment that has been used is cleaned and packed away. Wipe the table, ensuring all the chemicals have been removed of the table.

4.2 Original experiment

The original experiment used calcium carbonate chips, calcium carbonate powder and hydrochloric acid to determine how surface area effects the rate of the reaction. The rate of the reaction was measured using the scales and the time was recorded using a stopwatch.

4.3 Modifications

To ensure relevant and accurate data, the original experiment was refined by:

1. Doing several repeats in order to get an average which would make the data collected more reliable.
2. Washing all of the equipment after each trial, to ensure that the solution left over will not affect reactants for the next test. 
3. Shortening the experimental time to 5 minutes and recording the results each 20 seconds.

4.4 Management of Risks

Table 1: Risk assessment and management implemented for the surface area experiment

5.0Results

5.1 Raw data

Table 2: Raw data – obtained from experiment

Mass loss in the reaction between CaCo3 and HCl

Qualitive results:

There was a large difference between how vigorously the reactions occurred at different …. The 1M acid was the most vigorous and a large amount of bubbles were observed during the reaction. The 1M acid was the leats vigorous and produced much less gas bubbles.

Figure 1: Mass loss in the reaction between CaCo3 and HCl

5.2 Processing of Data

The mass loss for calcium carbonate chips and powder was calculated and placed into table 2. The 20 seconds time interval was placed against the mass loss to demonstrate the mass decrease between each 20 seconds for Calcium Carbonates. As expected, for powder, the average reaction rate for the first couple of minutes was significantly higher. The same relationship is evident for chips, However, it is slightly lower, compared to the powder. 

6.0  Discussion

6.1  Interpretation of results

The results show that increasing the surface area, it increases the reaction rate (Figure 1) According to multiple sources this occurs because the reaction rate can only be increased, by increasing the surface area. To increase the surface area, the material needs to be crushed into a powder. For less surface area, the material needs to stay in a big clump. 

6.2 Evaluation of methodology

Conclusion:

The three graphs together show the trend that as the surface area increases the rate of reaction increases.This observation is supported by collision thory which states that …

Results have shown that the hypothesis was supported by the results in the experiment. The results were accurate as well.

7.0 Reference list:

• Bbc.co.uk. BBC – GCSE Bitesize: Effect of surface area, 2017 http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/chemical_economics/reaction3rev1.shtml
• David N Blauch,2012, Chemical Kinetics: Reaction rates, viewed 4 June 2012, http://www.chemguide.co.uk/physical/basicratesmenu.html
• Chemguide.co.uk.The effect of surface area on rates of reaction, 2017, http://www.chemguide.co.uk/physical/basicrates/surfacearea.html
• Chemistry LibreTexts. Collision Theory, 2017, https://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Kinetics/Modeling_Reaction_Kinetics/Collision_Theory