The aim of this investigation is to investigate the time that it takes the jelly block to completely dissolve in water.

Jelly Blocks

Aim:

The aim of this investigation is to investigate the time that it takes the jelly block to completely dissolve in water. I can alter the size of jelly block, the amount of water in the beaker or the temperature of the water and see the time taken for the block to completely dissolve

Factors:

The main factors for this experiment are:

The Size of the jelly block. The size of the jelly block is a vital factor because a jelly block with a larger mass will be built up of more molecules. So if the mass of the block is larger than the dissolving will be much slower because dissolving occurs as the water molecules pull out the jelly molecules. Therefore more jelly molecules will mean that the water has to take a longer time to pull them out. If the mass of the jelly block is small then the time will be less because there are fewer molecules that have to be dissolved. To ensure that this factor works I have to make sure that I keep the amount of water and the temperature of water constant. The problem will be to get the exact amount of water and temperature. To keep the amount of water constant we can use a measuring cylinder. Similarly to obtain a constant temperature of the water we can use a thermometer. This is an easy factor providing you have digital scales, which we do.

The amount of water in the container. The amount of water in the container is an important factor because if there is more water in a container then that will mean that there are more water molecules. If there are more water molecules in the container that means that there will be more molecules that will bombard the jelly mass. Therefore one jelly molecule will be pulled out by more water molecules than before producing a stronger pull between the water molecules and the jelly molecule. This means that the more water, the quicker the time for the jelly to dissolve. If there is less water then there will be less water molecules so the dissolving will be much more slower. To make sure that this factor works I have to ensure that I keep the mass of the jelly and the temperature of the water constant. The trouble in this factor is that it will be hard to get the mass of the jelly block exactly equal so we can use a digital scale to insure accuracy. For the same amount of temperature we can use a thermometer. This is an easy factor to investigate and should give good results.

The temperature of the water. The temperature of the water is also an important factor because if the temperature of the water is higher then the water molecules will gain more Kinetic energy. If they gain more Kinetic energy that means that they will start to move around a lot more in the water. This means that the water molecules will collide more often with the jelly mass as a result of which the jelly will be dissolved much quicker. However if the temperature is cold then the opposite would happen and the time taken for the jelly to dissolve would be more because the water molecules will have less Kinetic energy. To investigate this factor I have to keep the amount of water and the mass of the jelly block constant. To solve the problem of getting the same amount of water I can use a measuring cylinder. To keep the mass of the jelly block constant I can use digital scales to insure ACCURACY. However this factor would be a difficult one to investigate because I would need very sophisticated equipment and if the temperature reaches the desired temperature then there will always be plus or minus 2 due to the time taken in removing the Bunsen burner from underneath and putting the jelly inside.

Factor to investigate (Input variable):

Mass of the jelly block in grams (g)

Outcome variable:

The time taken for the jelly block to completely dissolve in the water in seconds (s)

Prediction:

My prediction is that the larger the mass of the jelly block the longer it will take to completely dissolve. The reason is because in a larger jelly block there will be more molecules to be dissolved. This will affect the dissolving because the water molecules will have more molecules of the jelly to separate which will take more time.

...

This is a preview of the whole essay

Factor to investigate (Input variable):

Mass of the jelly block in grams (g)

Outcome variable:

The time taken for the jelly block to completely dissolve in the water in seconds (s)

Prediction:

Relationship between variables:

The relationship between the variables is that as the mass of the jelly block is increased the time taken for the jelly block to dissolve will be longer. Therefore the mass of the jelly block is directly proportionate to the time taken for the jelly block to completely dissolve in the water.

Fair test:

To make my experiment a fair test I have to use the same amount of water in each experiment. I have to do so because if there is more water than the dissolving will be much quicker due to the increase in the water molecules. If there is less water the dissolving will take much more time. So the experiment will be unfair if there is more or less water and it can affect my results. I can make sure that I have the same amount of water by using a measuring cylinder to measure the amount of water that I need

I also have to keep the temperature of the water constant. The reason for this is that if the temperature of the water is higher then the water molecules will gain more Kinetic energy therefore pulling out the jelly molecules much faster.

Another minor thing is to use the same type of stopwatch because some stopwatches require a bit more strength while others are too delicate. Minor but important if you want 100% ACCURACY.

Input variable+ Value or Values:

The input variable will be the mass of the jelly block and I will have three different measurements: 0.45g, 0.9g and 1.8g

Outcome variable + How it will be measured

The outcome variable is the time taken for the jelly block to completely dissolve in the water and it will be measured in (seconds) using a stopwatch

Controlled variables + values

Type of water + tap water
Type of jelly + English orange flavoured
Amount of water + 300ml
Temperature of water + 80°C

Method:

Get out all the equipment which is: A Bunsen burner, tripod stand, burning mat, wire gauze, measuring cylinder, beaker, water, pieces of jelly, digital scales, cutting boards, scalpels, stopwatch and a thermometer.
Take the blocks of jelly and cut them according to the way you want them to be. i.e. cut both the jelly blocks in half and then get three different masses of jelly with four trials each.
To make sure that each of your blocks are equal in weight, measure it using a digital scale.
First you get your measuring cylinder and put 300ml inside it. Once it’s checked you pour that 300ml into a beaker.
Get your Bunsen burner ready. Put the Bunsen burner on the mat and put the tripod over the Bunsen burner. Place the wire gauze over the tripod.
Using some matches turn on the gas and light up the Bunsen burner on the safety flame. Be very careful when using fire. When lighting a Bunsen burner always wear safety goggles. Whenever you aren’t using the Bunsen burner always put the flame on the safety flame.
Now you have to wait till the water reaches the desired temperature of 80oC. In the meantime you can fill the measuring cylinder again to speed up things.
As you’re checking the temperature occasionally stir the water so that you get the overall temperature as heat always rises.
Once the temperature reaches 80oC you do the following things quickly: remove the Bunsen burner from under the beaker and put your jelly block into the water. However when you put the jelly block into the water you have to start timing at the same time.
You keep timing until all the jelly is dissolved and everything is liquid. You then note down the time in seconds and milliseconds to be precise into the table.
Then using an oven glove you take your beaker and empty out the beaker. Be careful while handling the beaker, as it will be hot.
Then you start again and put the water in the beaker and repeat steps 7-11, till you have done the 4 trials with that same amount of mass.
Now you use a different mass of jelly and do 4 trials. You do the same for the 3rd mass.

NOTE: When you’re cutting out the jelly be sure to cut it in such a way that you have some left over incase something goes wrong.

Diagrams:

Trials:

I have to do the 2nd and 4th trial of my 0.4 g experiment again as my results are way of the line of best fit and don’t fit in with the pattern. I could have made an error with the timer or while measuring the mass of the block. However I still have some jelly leftover, which I can use.

Results:

When I am drawing my graph I am going to use only the average heights. However to make my graph easier to draw I’m just going to round of my results. Here are the averages that I’m going to use for my graph:

(They don’t make much of a change)

Now that I’ve done my 3rd and 4th trial for the 0.45g I can now tell that the results are right because they fit on the line of best fit. Here they are:

Discussion:

According to my graph and my table the main pattern that I discovered was that as you increase the mass of the jelly block the time taken for the jelly to dissolve in the water also increases. This shows me that the mass of the jelly block is directly proportionate to the time taken for the jelly block to dissolve in the water. From points 0.9g to 1.8g my graph is a straight line however the 0.45g point is quite off the line. It’s not on the line of best fit while the other two are.

The reasons for the 0.45g point not being on the line of best fit can be as follows:

When we were measuring the mass of the jelly block, even though we were using digital scales human error was likely and probably there could have been an error in weighing the mass of the jelly block as sometimes the scale is not exactly on zero at baseline.
The experiment was done on different days, which means that I could have used different types of stopwatches. Some stopwatches are different to others as some are very sensitive while others require a bit more strength. The 0.45g experiment was done on the different day then the rest, which could explain all the errors.
As I did the experiment on different days I could have used a different thermometer, as some have alcohol and some mercury. Both things have different rising points as they are heated. Minor difference but still worth considering as it can add up the error.
A very possible thing could be that once the water had reached 80oC we sometimes left the Bunsen burner underneath for a bit longer which would heat up the water more and cause errors. The other thing could be that when we took the Bunsen burner out from underneath we probably took too long to put the jelly inside and in that time the water could have cooled down.

One kind of mathematical pattern that I notice is that as you increase the mass of the jelly by twofold (i.e. from 0.9g to 1.8g) the time taken in seconds for the jelly to dissolve also roughly doubles. Here’s an example:

As the mass of the jelly block doubles from 0.9g to 1.8g the time taken for the block to dissolve roughly doubles from 21.60s to 41.40s. Ideally it should be 21.60s to 43.20s, however various errors, as explained earlier, are likely and that’s why it is not a perfect result. That’s more proof to show that the 0.45g is wrong because 13.20s comes to 26.40s for the 0.9g. However the 0.9g was 21.60s. Also if you compare the 0.45g to the 1.8g then according to the 0.45g the 1.8g should come to 52.8s. However the real 1.8g is 41.40s

Explanation:

The way dissolving occurs is that the electrons in a water molecule are unevenly spread out i.e. the oxygen end of the water molecule is partially negative while the hydrogen end of the water molecule is partially positive. As the water is heated the water molecules gain more Kinetic energy. This makes them move around more. As they are moving around they collide against the jelly and therefore the energy is transferred into the jelly molecules. Before the collision the molecules of the jelly are held together by a covalent bond and they are quite close to each other. However since the energy has been transferred from the water molecule to the jelly molecule the jelly molecules start to vibrate. Slowly the bonds that were holding the jelly together start to become weaker as there is less attraction. The jelly molecule would also have partial negative and partial positive so therefore the water molecule will create a new temporary bond with the jelly molecule and slowly the jelly molecule will be pulled out because there will be more water molecules surrounding it later. One by one the jelly molecules are pulled out from the giant structure and the jelly dissolves. Therefore to sum it up the water is the solvent, the jelly is the solute and once the jelly is dissolved it becomes a solution.

Evaluation:

My overall evaluation is that as you increase the mass of the jelly block you increase the time it takes the jelly to completely dissolve in the water, which means that the mass of the jelly block is directly proportionate to the time taken for the jelly to dissolve in water. This means that mass of the jelly block does affect the time taken for the jelly to dissolve in water. This proves my prediction right as I said “My prediction is that the larger the mass of the jelly block the longer it will take to completely dissolve.”

Overall my experiment was a fair test as I used the same amount of water; used the same stopwatch; and the same type of water and jelly. However there may be one thing, which could affect my experiment, which was that it was done on a different day and I could have used a different stopwatch. I could also have probably been a bit more accurate in my weighing and instead of just weighing the mass of the jelly block once, I should have done it two or three times, because sometimes the scale is not on zero.

If I were given the opportunity to do the experiment again I would try to complete it all on the same day so that there would be no errors. Also I would change the factor that I was investigating because if you’re measuring the mass of the jelly block then you are prone to mistakes in the weighing. I would change my factor instead and investigate whether the amount of water affects the time it takes the jelly to dissolve. It will be easier to accurately measure the amount of water and therefore the chances of mistakes are less. The reason for that being that even though you are still measuring the amount of water using a measuring cylinder you are using the same mass of jelly for each experiment. I enjoyed the experiment and I think it was accomplished with success!