Triple science – Addition polymerisation and energy changes

Recently in science we have been learning about energy changes in reactions and addition polymerisation.
Energy changes in reactions
When a chemical reaction occurs, energy is transferred from or to the surroundings. After this has happened, there is often a temperature change. There are two types of reactions, they are: endothermic reactions and exothermic reactions.
Exothermic reactions are reactions that transfer energy to the surroundings. Exothermic reactions result in a temperature increase. Examples of exothermic reactions are:
• Neutralisation reactions between acids and alkalis.
• The reaction between water and calcium oxide.
Energy is either taken in or given out during a chemical reaction. During an exothermic reaction, energy is given out. When the energy is given out it means the products have less energy than the reactants, this can be shown using an energy-level diagram. During an endothermic reaction, energy is taken in. If it’s an endothermic reaction the products will be higher than the reactants. Below is an energy level diagram showing endothermic reactions.

Addition polymerisation
Polymers are large chain of monomers joined together. Monomers are simple molecules that make up Polymers. Alkenes (methane, ethene, propene and butene) are able to act as monomers because they contain a double bond. They join end-to-end during the reaction called polymerisation. They polymers they form are called ‘addition polymers’.
The equation for addition polymers = a lot of monomers → a polymer molecule
Example 1 – with detail
Let’s start with propene and polypropene. The reaction which will take place is:
• Propene → poly(propene)

Shown below is the displayed formula for propene. In the previous blogs you should of have read how to draw and work out the displayed formula for alkenes. As you can see propene has 3 carbon atoms and 6 hydrogen atoms. The first carbon atom has 2 hydrogen atoms and is connected to a double bond which leads on to the next carbon atom with 1 hydrogen atom, then from there the final carbon atom which contains the final 3 hydrogen atoms.

Also below is the displayed formula for propene → poly(propene). As you can by the diagram to make the reaction propene → poly(propene), you have to take the propene molecule and bunch 1 carbon atom and 3 hydrogen atoms together to make CH3. After you have done that, to make the poly(propene), you take the exact same displayed formula as propene but this time you have to remove the double bond and put brackets around the formula. Once you have put the brackets in you then put a little n on the outside of it.

Shown below is the addition polymerisation reaction of polychloroethene

Uses of polyethene include:
• Material of plastic bags
• Material of dustbins
• Material of washing up bowls
• Clingfilm
• A drink bottles
• Strong material
• Easy to shape (malleable)
• Transparent

Uses of polypropene include:
• Material of certain floor tiles
• Milk bottles
• Making cable ties
• Very strong material
• Stronger than Polyethene
• More rigid than Polyethene

Questions based on these topics.
1. If you have a negative value what type of reaction do you get?
2. If you have a positive value what type of reaction do you get?
3. What is polymerisation?
4. What makes up polymers?
5. What is a monomer?
6. If you have Polybutene, what does polymerisation turn it into?
7. If you have chloroethene, what does polymerisation turn it into?
8. What does exothermic mean?
9. What does endothermic mean?
10. What term is used when describing the starting chemicals in a reaction?
1. An exothermic reaction.
2. An endothermic reaction.
3. Polymerisation is the reaction that makes polymers.
4. Long chains of monomers make up Polymers.
5. A monomer is a single molecule.
6. Butene.
7. Polychloroethene.
8. Exothermic is an increase in temperature.
9. Endothermic is a decrease in temperature.
10. Reactant.

Triple science- polymers

This week in triple science we have learnt about polymers and the structure of DNA. On Monday we learnt about polyesters. We also learnt about condensation reactions. Condensation reactions is a reaction in which two small molecules react form a larger molecule, with the elimination of water. To make a polyester by condensation you will need to draw out separately your diacid (which is a dicarboxylic acid) and your diol (which is your alcohol). You would then take away two of the H’s s and one O you take these away because they are lost to make water. After you have taken the water away you join the two together to make a polyester but you have to put a big bracket around each of then ends and draw lines through the bracket this is to show that the polyester and then be bonded on to other polyesters then you have to put a lowercase “n”. An example of how you lay it out is shown below. An example of a condensation reaction is of propanediol and butanedioic acid.

On Thursday which was our next triple science lesson we learnt about the structure of DNA. We learnt that DNA is made up of two strands and that it is made up of monomers known as nucleotide. The shape of a DNA strand is a double helix. We also learnt that there are four different nucleotides these are known as Adenine, guanine, thymine and cytosine. Adenine pairs with thymine. guanine pairs with cytosine. For example, if strand 1 was ATGGCATAGGCAT then strand 2 would be TACCGTATCCGTA. We also learnt about the structure of the DNA strands. This is a DNA strand example and what each piece breaks into

We also learnt that each 3 bases = triplet. Each triplet codes for a different amino acid. Each amino acid makes a different protein. Genes code for protein, proteins are made up of amino acids. Genetic codes are degenerate as more than 1 triplet can code for an amino acid. On Friday we did some revision on different topic in biology and created flash cards with the question and answers on them. Some of the questions were:
List the different organelles in a plant and their functions?
Nucleus- where DNA is found and controls the cell
Vacuole- stores water
Ribosomes- makes protein
Cell wall-supports the shape of the cell
Cell membrane- allows substances In and out of the cell
Chloroplast- where photosynthesis happens
Mitochondria- releases energy. site of aerobic respiration
Cytoplasm-where chemical reactions occur
Another question was:
What is active transport?
Active transport is where substances need to be absorbed against a concentration gradient from a low concentration to a high concentration. Active transport requires energy and a protein carrier. Happens across a partially-permeable membrane.

Triple science- organic chemistry

Recently in Science, we have been studying Organic Chemistry. This consists of balancing equations, alkanes, alkenes, alcohols, carboxylic acids, esters, combustion reactions, addition reactions, reactions with hydrogen, functional groups/ homologous series, reactions with sodium and ways of making ethanol.
A functional group is what gives a family of organic molecules their characteristic reactions. A homologous series is organic compounds with the same functional group. Therefore, the functional groups for the following are as below: -an alkane is C-C
-an alkene is C=C
-an alcohol is -OH
-a carboxylic acid is -C
Alkane- the general formula for an alkane is C n H 2 n+2
Alkene- the general formula for an alkene is C n H 2 n

Using the information above, answer the questions below
1. How many hydrogens would an alkane with 18 carbons have?
2. How many carbons would an alkene with 42 hydrogens have?
3. How many carbons would an alkane with 36 hydrogens have.
4. How many hydrogens would an alkene with 12 carbons have?

1. 38 hydrogens
2. 21 carbons
3. 16 carbons
4. 24 hydrogens

-The first four alkanes are methane, ethane, propane, butane.
-The first three alkenes are ethene, propene and butene.
-The first four alcohols are methanol, ethanol, propanol, butanol.
-The first four carboxylic acids are methanoic acid, ethanoic acid, propanoic acid and butanoic acid

Use the phrase “ Monkeys Eat Peanut Butter” to help to remember the prefixes for these molecules.

Combustion reactions
A combustion reaction is where a hydrogen reacts with oxygen to produce carbon dioxide and water.
For example:

Ethanol + oxygen → carbon dioxide + water
2C2H5OH + 6O2 → 4CO2 + 6H2O

Write a word and balanced symbol equation for the combustion reaction of propane.

Propane + oxygen → carbon dioxide + water
C3H8 + 5O2 → 3CO2 + 4H2O

What makes a strong acid?
– All acids make H+ ions in water.
– Strong acids are fully ionised in water to form H+ ions, therefore more H+ ions are formed.

What makes a weak acid?
– Only partially ionised to form H+ ions, therefore less H+ ions are formed.

– Carboxylic acids react with alcohols to make esters.
The general equation is:

Carboxylic acid + alcohol —> ester + water

Alkanes are saturated because they only have single bonds whereas alkenes are unsaturated because they contain both single and double bonds.

Addition Reactions
In addition reactions, alkenes lose their double bonds to become alkanes. For example:
Ethene + bromine → dibromoethane
C2H4 + Br2 → C2H4Br2

Reaction with hydrogen
Example: Ethene + hydrogen → ethane
C2H4 + H2 → C2H6
Reactions with sodium
When ethanol reacts with sodium, it effervesces. This means that it gives off bubbles of gas. The gas given off in this reaction is hydrogen. It gets smaller and smaller as it forms a solution of sodium ethoxide with ethanol.
Example: Sodium + ethanol → sodium ethoxide + hydrogen
2Na + 2CH3OH → 2CH3ONa + H2
Ways of making ethanol
Hydration of ethene and steam – ethene + steam → ethanol
C2H4 + H2O → C2H5OH
– It is a continuous process.
– It is a fast reaction.
– It makes pure ethanol.
– The raw materials are non-renewable.
– Needs to be in an area with a high temperature and high pressure.
– Requires a lot of energy.
Fermentation of yeast – glucose → ethanol + carbon dioxide (C6H12O6 → 2C2H5OH + 2CO2
– Only a little amount of energy is needed.
– The raw materials are renewable.
– It only needs to be in a warm area with a normal pressure.
– It’s a carbon neutral process.
– It’s a batch process.
– Needs to be filtered as it is impure.
– It’s a slow reaction.

Triple science week 5

This week in triple science we continued to learn about monoclonal antibodies. We began by learning about vaccinations, we learnt that vaccinations give us weakened/inactivated pathogens so our immune system can make the antibodies needed to fight them off in the future. Some of our white blood cells then become memory cells that remember how to make the specific antibodies for that pathogen.
We also found out that monoclonal antibodies are used in pregnancy tests. On a pregnancy test the monoclonal antibodies have a dye attached to them and they bind to HCG so when the person’s urine is in that area it detects if they have HCG or not. If they do, the monoclonal antibodies are trapped in an area further along the pregnancy test which makes that area turn to the colour of the dye. If they don’t have HCG the monoclonal antibodies go straight past that area. HCG is a hormone produced by the placenta when a woman is pregnant.
In our lesson we discovered that mouse lymphocytes are combined with tumour cells to make a hybridoma cell. The tumour cell divides continuously inside and outside of the body allowing many copies to be made and the mouse lymphocytes make the antibodies needed.
Our next lesson was on Wednesday and we learnt how monoclonal antibodies are used for cancer treatment. We learnt that monoclonal antibodies are used for:
• Blocking receptors on cells to prevent pathogens from binding.
• Binding to a pathogen and triggering an immune response.
• Drug delivery.
One advantage of using monoclonal antibodies is that they only bind to specific diseased or damaged cells, this way the other cells in that area won’t be harmed like they are in other treatments such as radiotherapy. A disadvantage would be that they initially created more side effects than expected, the monoclonal antibodies produced were mouse antibodies which triggered an immune response in humans.
In our last lesson of the week we learnt about growing bacteria in a lab. We now know that bacteria divide by binary fission. We also know that after a certain amount of time the bacteria would be forced to stop growing as there wouldn’t be sufficient nutrients to support all of them. We did a practical in that lesson where we grew our own bacteria. We were given agar plates which had been sterilised in an autoclave before we received them. We then had a Bunsen burner so that the heat would kill any bacteria in our working area. We had to put our inoculating loop inside the flame of the Bunsen burner in order to sterilise it. We then spread some E.coli it on the agar and sealed it with Sellotape to make it airtight and prevent cross contamination.
Exam questions that I think might come up on this topic:
1. Why do the agar plates have to be put in the autoclave before being used for experiments?
A. The agar plates are sterilised so there is no chance of cross contamination.
2. What is an antibody?
A. An antibody is a protein produced by white blood cells which bind to pathogens to kill it.
3. What is a monoclonal antibody?
A. Monoclonal antibodies are proteins produced from a single clone of cells.
4. What is a pathogen?
A. Pathogens are harmful bacteria.
5. What is a clone?
A. A clone is an organism that is genetically identical to another organism.

Triple science week 4

This week in triple science we started off the week completing a work sheet to show our understanding of finding the moment, distance and force. This helped us revise for an upcoming test to confirm we have mastered this topic.
Wednesday was our next triple science lesson. This lesson included learning about gears and how they work. A gear is made up of two teethed wheels where the teeth interlock to create movement. During this lesson we learnt that a smaller gear attached to a big gear means that bigger gear turns slower with a greater force. When two gears interlock this also causes a change in direction.
On Thursday we completed revision sheets which the teacher made for us from questions which needed to be completed. These questions were based on topics completed during this term in class. There were twelve different questions to complete.
On Friday we were introduced to monoclonal antibodies. In my opinion this was my favourite lesson of the week. This is because it was very interesting. We learnt that a monoclonal antibody is a protein produced from a single clone of cells. The antibodies are specific to a type of chemical or cell in the body. They are made by using mouse lymphocytes to make antibodies and combined with a particular tumour cell making a hybridoma cell. This allows the cell to divide and produce more copies of itself. This allows it to produce a lot of a specific antibody. This has been used in products such as pregnancy tests. It works by using unbound antibodies which detect human chorionic gonadotropin (HCG). The unbound antibodies will move down the test strip and if the woman is pregnant the antibodies will become bound to a secondary antibody and the dye attached to the antibody will make that section go blue. These monoclonal antibodies have revolutionised the diagnosis because you can now detect if somebody is pregnant earlier and they attach to HCG; a hormone present only if you are pregnant.
During our normal science lesson, we carried on about parallelogram of forces, explained to you during another student’s blog in week 3. Below are some images of what we have done this week.

Exam questions

1. Explain what the force and speed would be like if a smaller gear was attached to a larger gear.
A. The larger gear will turn with a slower speed but greater turning force.

2. What is a clone?
A. a genetically identical organism or cell.

3. How do you calculate moment?
A. forceX distance

4. What is a monoclonal specific to?
A. chemical or cell in the body

5. What hormone is present within the urine while you are pregnant?

Triple Science – Week 3

This week in triple science, we have been working on finding the moment and balancing the load and effort with the help of a lever.

During our lesson on Monday, we learnt about how less force is needed when you are further away from the pivot. For example, when opening a door, there is less force needed when you push the side furthest away from the hinges; due to there being a longer distance.

A moment is the turning effect of a force around a fixed point, also known as a pivot.

We then learnt how to work out the moment, distance and force when given certain measurements. This equation is: M
F x D
Moment is measured in Nm
Force is measured in N
Distance is measured in M

An exam type question that you may be given is:
A spanner is used to undo a nut. The force needed is 17N and is 10cm away from the centre of the nut. Find the moment.
Firstly, you convert the 10cm to metres due to the moment being measured in Nm. To find this we do 10 divided by 100= 0.1m. Then use the equation m=f x d. So, 0.1m x 17N = 1.7Nm – this is the moment.

Furthermore in another lesson we learnt about how the load of something on one side has to be the same as the effort on the other side. In a better form, the sum of the clockwise moments = the sum of the anti-clockwise moments. This therefore links with levers, a simple machine making work easier to do by reducing the effort needed to move the load. This happens by increasing the distance and levers are examples of force multipliers.

Another question you may be given is:
On the anti-clockwise side of the pivot, there is a load of 10N which is 7m away from the pivot. On the clockwise side, there is a load 2m away from the pivot but there is no measurement for the load. Please find out the force on the clockwise side if it is at equilibrium.
To do this, you multiply 10N by 7m which gives you 70Nm (the moment for the anti-clockwise side). Now use your moment (70Nm) and divide that by the 2m (the distance on the clockwise side)- giving you 35N, the force you were missing to find the moment.

In addition to this, during our normal lessons of science, we learnt about the resultant force of a parallelogram. To do this, we measured a bottom line, and then a diagonal line coming off of one of the corners. We then drew a line the same length opposite the horizontal line. Afterwards, we drew another diagonal line so all angles were the same, and all lines drawn were the same length as the other line (both horizontal lines were the same length). Finally, you draw a diagonal line through the middle and measure it accurately due to that being your resultant force of the parallelogram.

We also did a practical on finding the centre of mass of an irregular shape. We drew an irregular shape with 0 lines of symmetry, and then pierced a hole in one side and put it on a stand. We then hung a weight attached to a piece of string in front of our shape, and drew the line where the string hung. We kept doing this on different sides of our shape, and found the point at which all our lines met. This was then the centre of mass of our shape.

Below are some images of the work I have done this week.

Triple Science – Week 2

This week in triple science we were carrying out our planned experiments . We were given all the resources we needed and then it was up to us to complete the practical by using the method we had written. My hypothesis was the higher concentration of acid the faster the rate of reaction.
Some of us found that our experiments didn’t quite work and needed to be changed slightly in order to answer our hypothesis. Most of us repeated our experiments 3 times to make sure our results were reproducible and reliable. This was important because it helped us to see if we had any anomalies in our results and if we did we could see where something had gone slightly wrong.
It was quite challenging doing the experiment without being told how to do it first and without having help planning and carrying it out. I thought the practicals were a good way to help build confidence and be more independent. Also, we could get help from each other, for example if you weren’t sure what to do next instead of asking a teacher you could ask another student to help you.
In my experiment I tested the rate of reaction when adding different concentrations of hydrochloric acid to sodium thiosulfate. My concentrations of hydrochloric acid were 0.5m, 1m and 2m. This was a picture before the reaction of sodium thiosulfate and hydrochloric acid took place and a picture of it after the reaction.

I knew the reaction was finished because the clear liquids became a white colour and I could not see the cross on the paper underneath the glass beaker. The experiment went that colour because a sulphur precipitate was produced.

This was another student’s experiment measuring the effects of different concentrations on the amount of gas produced.

In Fridays lesson, the class took part in a quiz. We were separated into 4 groups, 10H1 Girls, 10H1 boys, 10H2 girls and 10H2 boys. In our groups we had to choose a runner. The runner’s job was to get a question from the middle table where our teacher was sitting and bring it back to our group. We answered the question and the runner took it back to the teacher to check. If it was correct we took another question to answer, if it was incorrect we had one more go before we lost the point. At the end of the game the scores were counted up to see which group had won. 10H1 AND 10H2 girls were joint first place followed by 10H1 boys then 10H2 boys. The quiz was a fun way for us to recap what we had learnt this term.

Exam question: Do your results support the hypothesis you investigated? Use examples from your results in your answer
Answer: Yes my results do support my hypothesis. I predicted that the higher the concentration of acid the faster the rate of reaction. My highest concentration was 2M and had the fastest time which was 24. My lowest concentration was 0.5M and took the longest time of 27 seconds.
Exam question: was your experiment reliable?
Answer: yes, my experiment was reliable because I repeated the experiment three times and got similar answers. There were no anomaly’s and when comparing results with another student, we found our results were similar. This means the experiment was reliable and reproducible.

Triple Science – Week 1

The theme of this week was the idea of being independent and being able to create an experiment to find out how certain factors affect the rate of reaction, without any help.

At the beginning of the week, we were given a booklet; within this booklet, we had to find two sources, briefly evaluate them, write a hypothesis, explain the hypothesis, write a brief method, complete a risk assessment and draw out the table for our results to go in. We started by choosing the factor we were going to test. For example, the choice were: Temperature, concentration, surface area or catalysts. I chose to do surface area. After this, we used iPads to research two different website which were appropriate to our chosen factor; we had to list what was good and bad about them. Furthermore, we used the information from our research to complete the booklet.

After we had completed the booklet, we were given another booklet to write everything up in detail and use it as preparation for our experiment. We had to explain the hypothesis, evaluate the sources, write a clear method and equipment list (describing the uses of the equipment) and then write a risk assessment and draw the exact table we would be using. All of this ensure that our experiments will run smoothly and the method needed to be clear so that anyone could look at it and repeat the same experiment.

To conclude, the part which I found the most interesting this week is that we have been given responsibility for our work and that we could choose the experiment and how we are going to investigate how our chosen factor affects the rate of reaction. Next week, we will be carrying out the experiment and finding out whether we have proved or disproved our hypothesis. One thing that I could say that I have found difficult is not being able to ask for help as I am someone who needs confidence in myself in order to be able to do my work without assistance.

Exam Questions

1) State 2 factors which affect the rate of a reaction. (2 marks)

2) Describe the effect of concentration on rate of reaction. (1 mark)

3) Explain why a reaction between concentrated acid and magnesium is faster than one with diluted acid. (3 marks)


1) 1 mark per factor.
Possible answers:
– Catalysts
– Surface area
– Concentration
– Temperature

2) 1 mark= As you increase the concentration, the rate of a reaction increases.

3) 1 mark = Concentration is increased
1 mark = Therefore there are more particles and more frequent collisions.
1 mark = Reaction will happen faster.

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