dear students today we shall learn properties of states of matter diffusion and solubility it's article number one in unit number one chemistry at excel international gcse we shall answer the chapter questions number 4 to 6 given on page number 12 and 13 diffusion the spreading out of particles in a gas or liquid is known as diffusion diffusion is the spreading out of particles from high concentration to low concentration area as you can see that in this container the higher concentration of particles are on a certain region when they get diffused means they move from this place and continuously moving to all parts of the container and they spread out until there is an equal concentration throughout the container here you can see there are two jars one jar is having bromine inside it which is having a brown color dark brown color and the upper jar it is having air inside it and these two jars are separated through the glass lid so the glass lid when it is taken out these two gases get mixed together and the bromine gas get diffused into the air and an air gas diffuse into the bromine part so the bromine is moving from the higher concentration to the lower concentration so it will take the time until unless the bromine and air get homogenized and the particles of bromine spread out until there is equal concentration in both the containers diffusion in liquids diffusion through a liquid is very slow if the liquid is completely still whereas in gases diffusion is very fast why the reason is the particles in the liquid move more slowly than the particles in gas and there is less space for particles to move into without colliding with each other solution is having two parts there is one party solute which could be liquid which could be gas would be uh solid as well most often water is the solvent but there are some other solvents as well which can mix some solutes into it and make a solution when the solid dissolves in a liquid the substance that dissolves is called solute liquid it dissolves in its called solvent and the liquid form is called solution saturated solution saturated solution is a solution which contains as much dissolved solid as possible at a particular temperature saturation of the different solutions depend upon the temperature we are taking on there must be some undissolved solute present when you see that here this is the saturated solution this undissolved solute present in it okay and here this is the solution which is having the maximum amount of solute the solubility of solids in a solvent solubility of sugar you are adding some sugar in water right water is a solvent and the sugar is solute after diffusion this gets all over the whole water and this becomes the sugar solution the mass of solute which must dissolve in 100 grams of solvent at a particular temperature to form a saturated solution is called the solubility it is the maximum mass of solute that dissolves in 100 grams of solvent at particular temperature for example the solubility of sodium chloride which is a common salt in water at 25 degree celsius is about 36 grams per 100 grams of water like we if you are taking a normal room temperature 100 grams of water in one glass and you pour into 36 grams of salt and you keep on stirring it at the temperature of 25 degree celsius and do not heat them then it get dissolved this is the maximum amount of sodium chloride which can get dissolved in 100 grams of water so if you increase the mass of water then definitely at the same temperature the mass of common salt or the mass of solute will also increase the solubility equals mass of solute over mass of solvent times hundred we shall use this formula to solve the next questions now solubility curves the solubility of solids changes with temperature and you can plot this on the solubility curve means you can plot that on graph most solids have solubility curves like those for the salts their solubility increases with temperature either dramatically or just a little you can use solubility curves to work out what pairs of crystals you would get it if you cooled a saturated solution difference of potassium chloride and potassium nitrate solution so if you take 100 grams of water for the both cases in one glass you are pouring potassium chloride and you're increasing the temperature as well you can see there is a very minor difference getting in for the solubility of potassium chloride look at this potassium nitrate the same temperatures and the solvent is same the mass of potassium nitrate is also same but the solubility is getting different is a huge difference so they are making a curve okay solubility curves for potassium nitrate and potassium chloride you are looking at that and temperature are on the x-axis and solubility of the solute per gram per 100 gram of water is on the y-axis chapter questions question number four to six this is question number four the experiment relies on the reaction between ammonia and hydrogen fluoride gases to give white solid ammonium chloride means nh3 in gaseous state when is added in hcl in gaseous state they come they join together and they make ammonium chloride but this is solid so this is a case of sublimation and deposition basically this is deposition is happening here so here this is the experiment operators cotton wool soaked in concentrated ammonia solution so this rule is having ammonia solution the other rule is having hcl solution so when they get uh fumes the fumes are coming out of it out of this soaked cotton they get together and there is a ring formed white ring forms closer to hydrochloric and so my question is explain why the ring takes a few minutes to form the answer is since ammonia and hydrochloric acid are soaked in the cotton wool in the liquid form and diffusion in the liquids are very slow so it takes some time for particles to diffuse along the tube question one part if you heat a gas what effect will this have on movement of particles answer gas particles will move faster after getting energy from heat more heat they get more kinetic energy they have and with the faster speed they move and collide with each other and spread all over the place second question in the light of your answer one what difference would you find if did this experiment outside on a day when temperature was 2 degree celsius instead of in a warm lab at 25 degree celsius explain your answer answer is ammonium chloride will take much more time to form because due to less temperature gas particles will move slowly and diffusion will happen at a lesser rate question c explain why the ring was formed near the hydrochloric acid end of the tube because hcl particles or molecules are heavier than nh3 particles so an three particles will cover more distance in less time and they can get diffused together nearer to hydrochloric acid d parts suppose you replaced the concentrated hydrochloric acid with concentrated hydrobromic acid this releases the gas hydrogen bromide and hydrogen bromide also reacts with ammonia to form a white ring suggest a name for the white ring in this case so we name the white ring is ammonium bromide as you can see through the equation ammonia gas when reacts with the hydrogen bromide gas it makes ammonium bromide so this is the name for this product second question is hydrogen bromide particles are about twice as heavy as hydrogen chloride particles what effects do you think this would have on an experiment the ring will form closer as half of the distance as made through hcl solution to hydrogen bromide end okay because hydrogen hydrogen bromide is double in the mass and heavier than hydrogen chloride so it will take much more time to release its molecules towards ammonia question 5 use the words given below to complete the following paragraph each word may be used once more than once or not at all so sodium chloride dissolves in the water to form a solution right the water is called solvent and the sodium chloride is called solute and the sodium chloride is called solute if the solution is heated at 50 degree celsius some of the water will evaporate until the solution becomes saturated sodium chloride crystals start to form as you can see that it's failed here question 6 the solubility of sodium chlorate in water was measured at the number of different temperatures temperatures are 0 20 40 60 80 100 and the solubility by 100 grams of water is at zero it's three temperature 20 degree celsius it's 8 40 degree it's 14 grams 60 degree celsius it's 23 80 degree celsius is 38 and 100 degrees celsius it becomes 55 use these figures to plot a solubility curve with the temperature on the horizontal axis and solubility on the vertical one so first of all we make the temperature table on x-axis we are writing the temperature and the y-axis we are writing the solubility of solute 100 grams of water and we draw the graph so solubility we have taken on vertical one and the temperature is on horizontal axis which is x axis and vertical axis is y axis so we have drawn the graph in which this all these points are showing at 0 degree celsius then 20 then 40 and then 60 then 80 and 100 so now we join these points and find out the next answer of question b question b states use your graph to find the solubility of sodium chlorate at 50 degree celsius when you look at the temp the curve and you see from on 50 degree celsius the curve is at this point and when we join this point to the y-axis we get this answer near to 20 and this becomes almost 18 so we write here the answer for b solubility of sodium chlorate at 50 degree celsius is 18 grams next question 6. solubility sodium chlorate in water determine the maximum mass of sodium chlorate that will dissolve in 40 grams of water at 30 degree celsius this is 10 20 30 40 and this is on 0 this is 3 and on the 30 degree celsius we look at the point which is joining on the vertical side this one is joining 10. so we can say that the solubility of sodium chlorate at 30 degree celsius is 10 grams but this is not required answer from us we have to work a little more on it as we know the formula for solubility is equal to mass of solute over mass of solvent times hundred solubility we know that this is 10 equals we don't know the mass of solute we can write it as x which is unknown solvent we are given this is 40 grams of water times 100 so we make the adjustment and 10 times 40 40 goes to the other side it multiplies 100 divides on the other side so it becomes x means x equals when we cut down these zeros we are getting only four grams means the 4 grams of sodium chlorate will dissolve in 40 grams of water at 30 degree celsius this is the maximum amount question d 20 grams of sodium chlorate was added to 100 grams of water and mixture heated to about 70 degree celsius it was then left to cool with the thermometer in the solution use your graph to answer the following questions at that temperature would crystals first appear in the solution and the second question if the solution was cooled to 17 degrees celsius calculate the total mass of crystals formed using this formula solubility and then the graph it is your assignment some of the working is already done and the hint is there try yourself and write your answers in comment box let me know if some problems you have i will get back to you and give the solution in next video so stay tuned thank you very much for watching don't forget to subscribe and share with your friends if you like the video