Nylon Rope Trick

Everyone has a favourite experiment, and this is one of mine. The look on the student's faces when the nylon is pulled from the interface.

Pour 5 cm3 of the aqueous diamine solution into a 25 cm3 beaker. Carefully pour 5 cm3 of the cyclohexane solution of the acid chloride on top of the first solution so that mixing is minimised. This is because the oil floats on the water layer. Do this by pouring the second solution down the beaker's wall or a glass rod.

The cyclohexane will float on top of the water without mixing.

Place the beaker below a stand and clamp it. A greyish film of nylon will form at the interface.

Pick up some of this with tweezers and lift it slowly and gently from the beaker. It should draw up behind it a thread of nylon.

Pull this over the rod of the clamp so that this acts as a pulley.

Continue pulling the nylon thread at a rate of about half a metre per second. It should be possible to pull out several metres.

The thread will be coated with unreacted monomer and maybe a narrow, hollow tube filled with monomer solution. Wearing disposable gloves is essential.

Making a salt from an insoluble metal oxide

Copper sulfate is often made because of its colour, but making white salts is just as good, just more difficult for the students to visualise, as the solution is not coloured. Therefore making Zinc Chloride is a bit more of a challenge. 

To make a salt from an insoluble metal oxide and an acid, the metal oxide must be reacted with the acid to produce a salt and water. The reaction can be represented by the following equation:

Metal oxide + Acid → Salt + Water

For example, if the metal oxide is magnesium oxide (ZnO) and the acid is hydrochloric acid (HCl), the reaction would be:

ZnO + 2HCl → ZnCl2 + H2O

In this reaction, the salt produced is magnesium chloride (ZnCl2).

 

Magnetic Field Strength

Investigating how the magnetic field strength changes as a probe is passed between two magnets, using @pascoscientific a rotatory motion sensor with a magnetic probe attached to it.

 

Model of a cell

A cell contains several structures, including:

1. Nucleus - The cell's control centre, containing DNA and regulating cell activity.

2. Endoplasmic reticulum (ER) - A network of membranes involved in protein synthesis and lipid metabolism.

3. Golgi apparatus - A stack of flattened membranes that modify, sort, and package proteins and lipids for transport to other parts or outside the cell.

4. Mitochondria - The cell's powerhouse, responsible for producing energy through cellular respiration.

5. Lysosomes - Small, spherical structures that contain digestive enzymes and break down waste and cellular debris.

6. Vacuoles - Large, fluid-filled organelles that store materials such as water, salts, and pigments.

7. Microfilaments and Microtubules - Tiny protein fibres that help maintain cell shape and support the cellular movement.

8. Peroxisomes - Small organelles containing enzymes involved in metabolic processes, including the breakdown of fatty acids and detoxifying harmful substances.

 

Spinning a wire connected to a beam galvanometer

How can spinning a single wire like a skipping rope connected to a beam galvanometer show electricity being generated? Nothing happens when both wires are spun together, but electricity is made if one of the pairs spins. And where does this energy come from? Fooled the students for quite a while. When a wire is passed through a magnetic field, a voltage, also known as an electromotive force (EMF), is generated in the wire. According to Faraday's law of electromagnetic induction, a changing magnetic field will induce an electromotive force (EMF) in a conductor. The EMF causes a flow of electric charges, which is an electric current.

In other words, the magnetic field acts as the source of energy that drives the flow of charges in the wire. The magnitude of the induced current depends on the strength of the magnetic field, the speed at which the wire moves through the field, and the length of the wire inside the magnetic field.

A beam galvanometer is a direct current (DC) electrical meter used to measure electrical current. It consists of a coil of wire suspended between the poles of a magnet. When a current flows through the coil, it creates a magnetic field that interacts with the magnetic field of the permanent magnet, causing the coil to rotate. The rotation angle is proportional to the magnitude of the current being measured. This movement is typically displayed on a scale or read out using a pointer. The coil is often attached to a lightweight metal beam or needle to increase its sensitivity, hence "the beam galvanometer."

Eureka Can

Science should be taught as a series of problems to find solutions to. Giving the student everything takes the excitement out of science. Science is about students discovering how to do something with a bit of guidance. I give out lots of the wrong equipment and get the students to choose what is best.

Charles Law

 It was the first time I had done Charles Law using a dried capillary tube and a bead of conc Sulfuric Acid to determine the volume against the temperature. The experiment took 3 hours, but I now know how to make it faster to fit into an hour lesson. Jacques Charles made a major contribution to the study of gases. In 1787, he discovered that gases have a linear relationship between their volume and temperature, provided the pressure remains constant. This is known as Charles's Law, which states that the volume of a gas is directly proportional to its temperature.