Chemistry Notes

1.  Industrial production of ethyl alcohol by fermentation               The raw material used for the large scale production of ethyl alcohol by the process of fermentation Molasses and starch. 1.1.  FROM MOLASSES  In our country  molasses is the chief raw material for the production of  ethyl alcohol. Molasses  contains about  30% sucrose  and about  32% invert sugar . As strong sugar concentration is not suitable for fermentation by yeast, it is diluted with water to a  10% sugar  solution called "  mash ". It is then transferred to a large steel tank called  fermenter  and made  slightly acidic (PH 4.0 to 5.0)  by adding  sulphuric acid . Acid prevents the growth of unwanted bacteria and promotes vigorous growth of yeast cells beneficial for  alcoholic fermentation. Required amount of  ammonium   sulphate  and  ammonium phosp...

6. SUNTAN LOTION :-      Sunlight possesses both  beneficial  and  harmful effects  on the skin . Exposure to moderate sunlight increases  blood circulation ,  produces vitamin D in the body,kills germs  and causes thickening of the skin to  prevent sunburn .these are the main  beneficial effects. However, long exposure  may damage the skin producing  erythema (  reddening ), painful burn,blister,swelling of the skin  and   something  skin cancer . Some natural protection against  sunburn  is obtained by thickening of the skin due to increased rate of  cell formation   at the epidermis and also increased  melanin  content of the epidermis. The purpose of suntan lotion is to  minimise  the  harmful effects  of the sunlight and to  assist tanning  of the skin . The suntan lotions are chemicals which act as sunscreen to absorb at l...

Q. what is colloidal particle and size ? Colloidal particle : the particle which cannot pass through the semipermeable membrane are known as colloidal particle. The size of colloidal particle is between 10 -7 – 10 -5 cm. Eg : starch, protein, albumin, gelatin.

INTRODUCTION   many types of raw materials can be used in the formulation of cosmetics. The choice of the raw materials involves the consideration of the following factors,viz. aesthetic value, colour ,availability, skin compatibility, environmental compatibility, smell acceptability ,stability and cost  . The stability refers to Physical,chemical and microbial stability. Cosmetic raw materials are mixtures of wide variety of individual components.      Some cosmetics and perfumes are given below:-- 1.   FACE POWDER:- The   function  of the face powder  is to mask any minor defect on the skin and supress oily patches so that the face appears to be smooth, beautiful and attractive. the modern face powder is a  mechanical mixture of several constitutents  each of which confers its own properties to the final blend.  The face powder should possess desired  covering powder, adhesion property, slip,a...

Q.1. What is SIGNIFICANT FIGURE  ?         SIGNIFICANT FIGURE                      the significant figure in a numerical expression is defined as these digit whose value are known along with additional digit whole value is uncertain. Eg :   24.82 cm having 3 certain digits are 2, 4, 8 and one doubtful digit is 2. Therefore, this reading has 4 significant figure. * Rules for determining the number of significant figure : 1. Except zero(0) all the digit 1 to 9 are significant. Example : 4.25 number has 3 significant figure. 71. 435 number has 5 significant figure. 2. All digits include zero are significant if zero appears in between non-zero digit. Example : 40.05 has 4 significant figure. 3. Zero to the left of the first non- zero digit in a number is not significant. It indicates only decimal point. Example  : 0.4 28 has 3 significant figure. 0.054 has 2 significant figure. 4. ...

Q.1. What is ERROR ? Error  is defined as the numerical difference between  measured value  and  true value  in analytical determination. Q.2. What are the different types of           error ? Error is of two types :-            1. Determinate error            2. Indeterminate error . 1.  Determinate error The errors which can be avoided or whose magnitude can be determine and can be rectified are called determinate error. These errors are caused by defecting experiment apparatus or technique when in the measurement of weight of substance is uncalibrated weight are used then the weight in term of error is known as determinate error. Uses  - This error can be rectified or remove replacing uncalibrated weight. Determinate error is of  three types  1. Instrumental error. 2. Personal error. 3. Error of method. 1.  Instrumental er...

What is ACCURACY And PRECISION  ? ACCURACY   : accuracy is the closeness between the measured value and accepted or true value of the measured quantity.            The accurate value of the sample can be determined by  averaging the precise value. Eg  :  in a organic sample the percentage of carbon 49. 50 by the analysis off two analyst are as follows :-    A --49. 40, 49. 47, 49.53, 49.64   Mean = 49.51   B -- 49.01, 49.03, 49.03, 49.04   Mean = 49.03 Therefore , A is more accurate than B. WHAT IS ERROR  AND ITS DIFFERENT TYPES (in chemistry) PRECISION   : the agreement between a set of result made on same sample in an identical manner is known as  precision of the measurement  i.e., precision reflects the closeness among the replicate measurement of the same quantity. Eg  : In an organic compound two analyst analysis as follows :- A -- 49.40, 49.47, 49...