1. A small amount of liquid bromine is placed in a gas jar, which is then sealed with a lid.            Evaporation of the liquid bromine takes place.

Br2(l) ➞ Br2(g)

Use the ideas of the kinetic theory to explain why, after about an hour, the gaseous bromine molecules have spread to evenly occupy the whole container.

Ans ) The molecules of liquid gets mixed with the air and starts to get loose , the liquid particles slowly act like gaseous particles , they become loose and roam around 

2. A teacher carried out a class demonstration on diffusion similar to that using ammonia (Mr = 17) and hydrochloric acid (Mr = 36.5) (Figure 1.21). However, they replaced the ammonia with methylamine (Mr = 31), which reacts in a similar way to ammonia (note that Mr is the relative molecular mass of the substance).

A. Where would you predict the position of the smoke ring to be in this experiment? Explain your answer.

B. Suggest other gasses similar to hydrochloric acid that could replace it in this demonstration (use textbooks or the internet to find a possible acid).

1. The smoke ring is expected to be in the top of the container 

2. Nitric oxide

Kinetic particle theory of matter activity

• Modeling the arrangement of the particles in a solid, liquid or gas is one way to help understand the properties of the different states of matter.

Questions

1. What could you use to represent the particles? (Balls or marbles in a tray or dish, circular pieces of card on a plate, groups of people, symbols perhaps?)

1. How will you arrange the particles to demonstrate solids, liquids and gasses?

1. How could you represent the movement of the particles?

1. Why can three states of matter exist?

1. Why is it that it takes time for a solid to melt?

1. Why do solids not diffuse over a normal time period?

1. What is different about substances that means that they each have different melting points?

1. Different substances also have different boiling points. Is the reason for this similar to why they have different melting points?

1. Why is it that you can feel a liquid cool when it evaporates in your hand?

Answers

• Would represent particles as marbles or clay

• I would arrange the particles as clay , if solid sticking , if liquid loose and if gas very open 

• Through marbles or cricket balls. Would stick them with a rope 

• The 3 states of matter were created in the big bang

• For the temperature to slowly go up

• It takes time for solid particles to start moving fast and vibrate

• Particle number difference , the atomic mass will have a difference 

• Yes it is similar

• Air hits our hands with more sweat coming out from our body