 Today we are going to learn a topic lubricant and from that topic we are going to learn a particular point that is problem solving section how to calculate the acid value and saponification value of a given sample of lubricant. This is the learning outcome for today's session. First we will learn the basic terms involved that is what do mean by acid value and saponification value of a lubricant sample. By knowing the theoretical concept of these two terms that is acid and saponification value then we will apply the knowledge to calculate the same that is acid value or the saponification value of a given sample of lubricant. This is the content. First we will learn the different types of properties of lubricant. Then we will come to our point that is acid and saponification value. These are the two important terms of the today's session and then we will learn how to calculate acid value and saponification value of a given sample of lubricant. What do mean by lubricant? Lubricant we know it is a material. So for using every kind of machine a material is needed to introduce between two metallic surfaces to avoid wear and tear is known as lubricant. So what is lubricant? It is a material that is used in between two metallic surfaces to avoid their direct contact to protect them from wear and tear and that material is known as lubricant. Lubricants are mainly used for avoiding direct contact of moving surfaces to absorb frictional heat and to maintain efficiency of the machine. Solid, liquid and semi-solid lubricants are used under different working conditions of the machine. So these are the three possible types of lubricants such as solid, liquid and semi-solid lubricants. This mainly shows viscosity, viscosity index, oiliness, acid value and saponification value as an important properties. So the usefulness of that lubricant, the selection of that lubricant for a particular given machine is based after learning its properties and what are the machine requirement. So how much it is viscous that is viscosity, what is its viscosity index, what is its capacity to stick the surface that is oiliness and how much acid and how much fatty acids are present in that particular given sample is known as acid value and sap value of that lubricant sample. There is a great impact of these properties on the objective of lubrication of the machine. Acid value of a lubricant indicates level of mineral acids present in the sample and saponification value indicates level of fatty acids present in the sample. So acid value and sap value what they indicate first acid value indicates what is the level of mineral acids present in a given sample of lubricant and saponification value indicates what is the level of saturated fatty acids present in a given sample of the lubricant because the reason is that the source of the lubricant is in nature that is either animal oil, vegetable oil or the mineral oil. So there is a more possibility of coming either mineral acids or fatty acids in the given sample of the lubricant. So before its use before its selection we must measure how much mineral acids are there and how much fatty acids are there. Now we will come to the definition of acid value. How it is defined? The numbers of milligram of KOH required to neutralize the free acids present in 1 gram of the oil. So it is correlated with the titration because how we are going to determine? We are going to determine by titrating the given sample with KOH and we know that it is a simple acid based titration because acids are present in a sample. We are titrating the sample with a KOH just it is a neutralization and we are measuring how much KOH is consumed for neutralization and from that we are coming to know what is the level of mineral acids present in a given sample of the lubricating oil. So what is its definition? One more time I will repeat the numbers of milligram of KOH required to neutralize the free acids present in 1 gram of the oil. Therefore acid number or value is equal to number of ml of n by 10. N by 10 means n is always 1 normal 1 upon 10 that is 0.1 normal KOH divided by weight of the oil taken in gram multiplied by 5.6 that is a standard factor. Similarly what is the definition of saponification value? The numbers of milligrams of KOH required to saponify the total fatty acids present in 1 gram of the oil. Only the difference is that in case of acid value we are determining the mineral acids and in case of saponification value we are determining the fatty acids because the concept is that in acid value we are titrating with base and in saponification value we are treating with the alkali solution that is KOH where the fatty acid converts into soap and how much KOH is consumed for this process gives us the knowledge about the total milligrams of the fatty acids present in 1 gram of the oil. Therefore saponification value is equal to volume of n by 2 HCl in a blank experiment minus volume of n by 2 HCl for a test experiment divided by weight of the oil in gram multiplied by 28. Now I would like to ask one question here lubricant is used with the objective of and the correct answer is that all of these because A is also correct, B is also correct and C is also correct. Now we will apply the theoretical knowledge in case of determination of acid value and sap value of a given sample. So, this is problem number one in an acid value determination experiment for 8 gram of an oil 13.5 ml of KOH is required for phenophthalene end point calculate acid value of the sample. So, what is the given data the weight of the lubricant sample we have used is that 8 gram how much volume of KOH we have required for neutralization 13.5 ml so that is consumed for neutralization of mineral acids present in the sample. So, by using the formula we will put the values. So, 13.5 is the number of ml of n by 10 KOH divided by weight of the oil sample is 8 and multiplied by the standard factor 5.6. Therefore, the acid value or which is also known as acid number of a given sample is 9.45. One more numerical we will see the same that is in an acid value determination experiment for 8.9 gram of an oil 23.5 ml of KOH is required for the phenophthalene end point calculate acid value of the sample. So, what is the given for numerical in this numerical we are using 8.9 gram of an oil sample and we are carrying out the neutralization where we observed that 23.5 ml of KOH has been consumed for neutralization. It is simple acid based titration we are used phenophthalene end point and the end point for such experiment is that color less to pink when we got the pink color then we will stop the addition and then in particular case it is mentioned that for the end point we have required 23.5 ml of KOH. Then we will put the same value in the formula therefore acid value is equal to 23.5 divided by 8.9 is a weight of oil multiplied by 5.6. Therefore, acid value of a given sample is 14.78. Now, we will see the another type of the numerical where we are going to find out the saphenification value of an given sample. Now, what is the numerical 7 gram of an oil sample after reflecting with 50 ml volume of KOH solution which on subsequent titrating with 0.2 normal ethyl solution gives 7.8 ml of burette reading for neutralization to phenophthalene. A blank experiment was performed and found 50 ml of burette reading for neutralization calculate sap value of an oil sample. So, first of all I will clear you what do you mean by this statement. In this statement the two parts are there one is up to phenophthalene and second part starts from a blank experiment. So, there are two experiments up to phenophthalene is one experiment and blank experiment is another experiment. Now, what happened in first part we are using the 7 gram of the oil we are mixing with the 50 ml of KOH and we are heating for a subsequent period of time. In this process what happened saphenification process completes and what do you mean by completion of saphenification process all the fatty acids have been converted into soap. Now, how to come to know what is the exact KOH volume is consumed for this process we don't know then after saphenification to the same sample we are carrying out the simple experiment that is acid based titration. Then the sample is used for titration with 0.2 normal ethyl solution which gives 7.8 ml of burette reading that means 7.8 ml of KOH is left out of 50 because initially if you see in first line we have used the 50 ml, but we don't know how much consumed but after titrating the sample with ethyl we come to know that as we got the burette reading 7.8 ml therefore 7.8 out of 50 KOH is left and what is second a blank experiment without taking oil we are carried out the same experiment. So, as there is no oil no fatty acids are there therefore directly 50 ml is a burette reading. Now, what is the standard formula volume of n by 2 ethyl in a blank experiment and volume minus volume of n by 2 ethyl in a test experiment divided by weight of the oil multiplied by 28. So, if you put the value that is 50 that is blank minus 7.8 divided by 7 is oil weight multiplied by 28 which comes 168.8 therefore saphenification value of a given sample is 168.8.