Investigating the rate of reaction between hydrochloric acid and calcium carbonate

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  Investigating the rate of reaction between  

 hydrochloric acid and calcium carbonate  


I will carry out an experiment to find out how the changing the concentration affects the reaction between hydrochloric acid and calcium carbonate. The Balanced equation for this is  

CaCo3 + 2HCL ----> CaCl3 + H2O + CO2  

calcium carbonate + Hydrochloric acid --> calcium chloride + water + carbon dioxide  

The variable I will change is the concentration to find out what effect more concentrated and dilute solutions have on how long it takes for the mixture to turn clear  

I am going to time the reaction until it finishes I will know when to stop the reaction by placing a cross under the conical flask which will determine when the calcium carbonate is used up because the mixture will turn clear and the cross will be visible. Calcium carbonate is a solid that turns Hydrochloric acid translucent when reacted together but it is expected to turn cloudy & bubble. The time taken for a certain amount of calcium carbonate to disappear can indicate the rate of reaction. I will time the reaction by using a stop watch when calcium carbonate is added to Hydrochloric acid. I will vary the reaction by using different concentrations which require water to dilute the solution.  


Background Knowledge Rate of Reaction: This is the speed at which a reaction takes place. The chemical definition of rates of reaction is the rate of the chemical reaction as the change in  concentration of any reactant or product  in a solution is increased which is measured by unit in time. increasing the concentration , surface area ,adding a catalyst, gas pressure, reactants in solution , and temperature are all variables that can affect the rate of reaction. by increasing the amount of reactants in the chemical reaction  there is a higher chance of particles colliding because there are more of them in the same volume the more frequently the particles collide the more chance of an increase in the rate of reaction.Increasing the concentration of acid molecules increases the frequency or chance at which they hit the surface of calcium carbonate to dissolve them. The effect of Pressure If one or more of the reactants is a gas then increasing pressure will effectively increase the concentration of the reactant molecules and speed up the reaction. The effect of Surface Area If a solid, reactant or a solid catalyst is broken down into smaller pieces the rate of reaction increases. The speed increase happens because smaller pieces of the same mass of solid have a greater surface area compared to larger pieces of the solid.  


Two beakers -   one for water and one to hold the contents of hydrochloric acid it is more efficient and safer when pouring into the measuring cylinder to measure amount needed for experiment. overall accurate and reliable but doesn't have enough integers to use for mixing reactants so must be measured in measuring cylinder and mixed in conical flask  

Two measuring cylinders - accurate measure of liquid contents two needed to measure amount of water and hydrochloric acid to be used in the experiment more integers and better scale bigger and easier to record accurate readings with.  

scales - measures mass of calcium carbonate very sensitive particles in the air or surroundings can have a small impact on the reading of scales and surface where the scales are placed but overall very reliable and can be double checked for an accurate reading.  

watch glass - holds calcium carbonate powder and is easier to pour into the conical flask to mix the reactants is effective when moving when calcium carbonate on the watch glass is being poured into the conical flask it is easier to make sure exact amount of solid is used.  

goggles - safety measure taken to avoid toxic , irritant chemicals from harming eyes. useful and accurate/reliable because it has a thick layer of plastic for protection.    

spatula - allows small amounts of calcium carbonate powder to be measured and put onto the watch glass to avoid mess and is more efficient. certain of accuracy and reliability  

stopwatch - times the reaction reliable but to make sure it works should be tested before starting the experiment.  

2conical flask - is where the reactants are mixed together good integers reliable because of the shape transparent to it is clear to observe reaction taking place.  using 2 conical flasks keeps the test fair because when the concentration of acid is not diluted to avoid any traces of water it is better to use a separate conical flask.

Small mat with a cross - this is key to this experiment and will give me an idea of how quickly the reaction is occurring and whether the reaction is neutralized or not because the cross is only visible when the mixture turns clear.  

all very accurate and reliable but to avoid any complications and a fair test to be safe all equipment should be tested to see if they work effectively.  I believe my equipment are accurate because when I am using multiple equipment for example 2 beakers they are the same size and the integers on the measuring cylinder and conical flask are accurate especially with the volume of acid I am using throughout the experiment this allows me to keep track of  the volume of reactants and the product formed.  

Fair test  

To keep my test fair it is important to maintain the same variables and use the exact measurements repeatedly. variables that can affect the rate of reaction in this investigation are :  

1. The temperature of the hydrochloric acid.  

2. The amount of hydrochloric acid.  

3. The concentration of the hydrochloric acid.  

4. The surface area of the calcium carbonate.  

5. The amount of calcium carbonate.  

6. The form of calcium carbonate. (It is available in three forms  

powder, small stones or large stones)  

7. You can speed up the reaction by stirring the solution.  

8. You can also change the rate of the reaction by adding a catalyst,  

which is something that speeds up the reaction.  

In my investigation I will be trying to find out the affect of concentration on the timing of the reaction therefore I will only variable I will be changing is the volume of hydrochloric acid by diluting it with water.

which means to keep it a fair test  I will use the same amount (0.1g) of calcium carbonate which is a powder because this allows us to see the cross disappearing I will time the reaction until it finishes.  I will use five different dilutions of hydrochloric acid and water which have a difference of 5 between them to keep it a fair test and in order to have the most accurate results.I will also wash out the beaker in which I will perform the experiment after each use. I will also repeat my experiment twice to confirm that the results are correct and that there are outliers. I will also use the same person to do each specific task in the experiment for example one person measuring the mass of calcium carbonate to get an accurate set of results. and by making no changes to the method using the same method throughout the experiment is crucial and has a large impact on the results I get. If one step in the method goes wrong for example using the wrong amount of hcl in one of the experiments the results we get will not be recorded but not all variables can be controlled for example room temperature can affect the results and we cannot change that. we also don't know the amount of particles are the same this could affect the results but is a variable that cannot be changed.

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I could get results for this experiments by recording a number of  

things, I could record:  

The effect of temperature.  

The amount of gas produced by the reaction in a certain amount of time  

The mass lost during the reaction.  

I am going to record the amount of time it takes for the calcium carbonate to dissolve I will time this until the reaction is finished when the mixture is no longer cloudy. This is a neutralization reaction  so when the mixture turns clear this means the base has neutralized the acid I predict that ...

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