INCREASING SURFACE AREA:
In this experiment, we chose to change the surface area of the Tums and not the liquid since to increase the surface area of the liquid, we must heat it to evaporate it. By evaporating it, the surface area would increase as the particles moves faster and collide more frequently with each other. However, this reaction rate would then be of raising the temperature, another factor that speeds up reaction rates. Although we have increased the surface area by increasing the space between the molecules, we have also raised the temperature. On the other hand, by crushing the Tums tablet, a solid, we have just simply increased the surface area by exposing a bigger area to react. In this process we have not brought any other factors in.
SECTION 2
Affect of Temperature on the Rate of Reaction of Alka-Seltzer
In order for a chemical reaction to occur, the reactants must physically come into contact with one another. Many factors increase the occurrence of these encounters which speed of the reaction. This investigation is to observe how any increase in temperature will affect the rate of reaction. It is expected that the greater temperature will result in increase in the rate of reaction.
MATERIALS/METHODS
- Safety goggles
- 2 Film canisters
- 10-mL graduated cylinder
- 2 Alka-Seltzer tablets (1.8 g each)
- Hot water
- Kettle
- Balance
- Stopwatch or timer
- Thermometer
- Safety goggles were put on
- Heated water in kettle, using thermometer to determine temperature
- 10 mL of water was measured in the graduated cylinder and poured into the film canister
- One Alka-Seltzer tablet was measured in mass and placed into the heated water
- The lid was secured on the film canister to prevent gas from leaking in or out
- The stopwatch recorded the time it took for the Alka-Seltzer tablet to react from the time the lead was put on, to when it came off
- Repeated steps 3-6 using room temperature water
- Calculated the data into rates of reaction using the formula g/s
OBSERVATIONS AND CALCULATIONS
Change in the Rate of Reaction: Temperature
DISCUSSION QUESTIONS
This investigation turned out as hypothesized and proved that an increase in temperature results in an increase in the rate of reaction. In the experiment, the rate of reaction of water at room temperature was 0.3 g/s and when the water temperature was increased by 49°C, the rate of reaction increased to 0.325, almost twice. These results seem right since according to the collision theory, raising the temperature makes the particles move faster. This means that the particles more frequently with each other and the rate of the reaction increases. The stronger the collisions, the easier the chemical bonds break apart and therefore, the quicker the reaction. The rate of reaction of the Alka-Seltzer could have been higher in the heated water. The water was poured in the beaker to measure the temperature by using a thermometer, this took a few seconds. During these seconds, the water had cooled off a little. Also, the accuracy of the time is somewhat questionable since the tablet begins to react from the time it is put in the heated water. However, we only calculated the time from when the cap of the film canister was put on.
RAISING TEMPERATURE:
We convert the data into rates of reactions because it is more difficult to compare data when they have different units. Some groups may have used half of an Alka-Seltzer tablet; others may have used one whole. It is therefore easier to find an accurate comparison using rate of reaction.
SECTION 3
Affect of Concentration on the Rate of Reaction of Alka-Seltzer
The rate of a chemical reaction depends on the frequency of the collisions between the atoms or ions of the reactants. The purpose of this investigation is to see how a greater concentration of liquid affects the rate of reaction. It is expected that as the concentration of the reaction increases, the frequency of collisions increases, and the rate of the reactions increases.
MATERIALS/METHODS
- Safety goggles
- 2 Film canisters
- 10-mL graduated cylinder
- 2 Alka-Seltzer tablets (1.8 g each)
- 10 mL of HCL
- Balance
- Stopwatch or timer
- Safety goggles were put on
- 10 ml of HCL was poured into the film canister, using a graduated cylinder to measure quantity
- An Alka-Seltzer tablet was measured in mass using a balance and placed into the canister
- The cap was placed quickly and firmly on the film canister to prevent gas from leaking in and out
- The stopwatch recorded the time it took for the Alka-Seltzer tablet to react from the time the lead was put on, to when it came off
- Repeated steps 2-5 using water
- Calculated the data into rates of reaction using the formula g/s
OBSERVATIONS AND CALCULATIONS
Change in the Rate of Reaction: Concentration
DISCUSSION QUESTIONS
This investigation’s results were as hypothesized and that the rate of reaction speeds up when the concentration of one of the reactants is increased. The cap of the film canister containing water popped after 6 seconds, while the cap of the canisters containing HCL, a higher concentration, popped only after 4 seconds. The rate of reaction is almost doubled with the increase in concentrations.
These results seem right since according to the collision theory, the more particles that are in the same volume, the closer to each other the particles will be. This means that the particles more frequently with each other and the rate of the reaction increases. A higher concentration makes it easier for compound bonds to break apart.
INCREASING THE CONCENTRATION:
In this experiment, we chose to increase the concentration of the liquid and not the Tums.
The concentration of the liquid was increased by using Hydrochloric acid instead of water. By doing this, we increased the concentration of a substance in a solution as the number of particles increased. The more particles that are in the same volume, the closer to each other the particles will be. However if we were to increase the concentration of Tums, there would still be an increased rate of reaction, however this rate of reaction would be from increasing the surface area since crushing it into smaller pieces would mean more particles. However, this would not be accurate because this reaction is a result of an increased surface area, not the concentration.
STSE QUESTIONS
A chemical reaction is the pathway by which two substances bond together. This reaction does not always happen in a laboratory or a science class room; Chemical reactions happen all around us. An essential example can be found in agriculture. The most basic chemical reaction that all life depends on is Photosynthesis: water and carbon dioxide react to form sugar and oxygen or 6H2O + 6CO2 → C6H1206 + 6O2. Photosynthesis is the basis of all life and, no plant or animal, could exist on earth without it. Photosynthesis is harnessed by plants while a similar reaction, photochemical reaction, is harnessed by humans. Photochemical reaction is involved in photography which reproduces permanent images on light sensitive materials. Light reacts with silver halide crystals on the paper to form a hidden image. Photon energy from the lights takes out electrons on the paper. The paper is then placed in a basic solution such as Dektol which magnifies the reaction causing silver to clump together and darken in certain areas forming the image. Lastly, cold packs are used by athletes to minimize swelling injuries such as muscle and joint sprains. These packs consist of two compounds- urea and ammonium chloride in separate containers within the package. When the bag is bent and the containers are broken, the two compounds mix together and begin to react. Because the reaction is endothermic, it absorbs heat from the surrounding environment and the bag gets cold.
The chemical reaction involved in photosynthesis is:
Carbon dioxide + water glucose + oxygen
The main factors affecting the rate of photosynthesis are carbon dioxide concentration and temperature. An increase in the carbon dioxide concentration increases the rate at which carbon is incorporated into carbohydrate in the reaction and so the rate of photosynthesis generally increases. This is because increasing the concentration means that there will be more particles in that volume, decreasing the space between the carbon and the carbohydrate particles. Photosynthesis is also dependent on temperature. Temperature speeds up all chemical reactions and photosynthesis is no exception. Photosynthesis requires enzyme activity; enzymes work better in warm conditions. For instance, increasing the temperature from 10°C to 20°C could double the rate ph photosynthesis as the plants enzymes will be at their working temperature. As the temperature increases, molecules in the cells will be moving at a faster rate therefore, they will be colliding with each other more, breaking more bonds and reacting at a higher rate.