States of matter and kinetic theoryIB MYP Chemistry: Mind map

Exam questions on States of matter and kinetic theory

1. In a science lesson in Lagos, students seal the nozzles of two identical syringes. One syringe holds 20 cm³ of air and the other holds 20 cm³ of water. When the students push each plunger in firmly, the air syringe squashes to about 5 cm³ but the water syringe hardly changes volume. The teacher then draws the particles in each syringe as small hard spheres.
   Explain why the water in the syringe hardly changes volume when the plunger is pushed.2 marks
2. A metal worker in Seoul heats a solid iron bar from 20 °C to 300 °C in a workshop. The bar becomes slightly longer but stays solid and keeps its shape. Later in the day the same bar is heated in a furnace until it melts.
   Explain, using the particle model, why the iron bar becomes slightly longer when heated but stays solid.2 marks
3. Students in Santiago want to test the hypothesis that a gas is more compressible than a liquid. They seal the nozzles of two identical 50 cm³ syringes, one filled with 50 cm³ of air and one with 50 cm³ of water. They place the same 5 kg mass on each plunger, wait until the plunger stops moving and read the volume. Safety glasses are worn throughout.
   Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks