Calculation of absolute alcohol

Instruments, laboratory glassware and reagents: alcoholometer glass, thermometer, glass cylinder, ethanol.

Progress definitions

Ethanol is mixed with water in any ratio. This process is accompanied by a change in the amount of heat and aqueous-alcoholic fluid (adiabatic compression - contracting), which depends on the concentration of alcohol in the solution. Alcohol content in water-alcohol solution measured in dry year. The unit take 1 dl of waterless alcohol.

Content waterless alcohol Sb.s. in the water-alcohol solution at 20 ° C are finding by multiplying the volume of water-alcohol solution on the alcohol content in the C volume fractions, dl:

С_б._с=VC

When counting the number of water-alcohol solutions have their volumes measured at arbitrary temperatures. But it is well known that temperature influences the alcohol content per unit volume.

To transfer different volumes of water-alcohol solutions having different temperatures, in anhydrous alcohol at 20 ° C using a table of factors. Multiplier are finding the content of alcohol in volume fractions and the temperature at which the measurement was performed.

Volume of water-alcohol solution, which is found at a given temperature, multiplied by factor K and found getting the volume of waterless alcohol in the liquid at 20 ° C dl:

С_б._с=VК

Examples of the use of tables to determine the strength of water-alcohol solutions

Example 1. Volume of water-alcohol solution at a temperature of 14 ° C is equal to 4000 liters with alcohol content of 0.963 volume of shares (96,3% vol.).

Find the amount of of waterless alcohol.

As Table factors for conversion on the anhydrous alcohol intended for integer values ​​of alcohol and temperature, when the calculations are fractional numbers, the multiplier are finding by linear interpolation.

In table factors for the determination of alcohol with a volume fraction of alcohol are: 0.9662 and 0.9762. For finding the multiplier to determine the content of alcohol with a volume fraction of 0.963, using the following equation:

(0.9662-x) / (96,0-96, ZYO,9662-0, 9762) / (96,0-97,0), x = 0.9692% vol.

Thus, the amount of waterless alcohol 4000 * 0.9692 = 3876.8 liters.

Example 2. Volume of water-alcohol solution of 20,000 liters at a temperature of 17,5 ° C when the content of alcohol by volume 0.9558 shares (95.58% vol.).

Find the amount of of waterless alcohol.

In the table find the value multipliers for neighbors integers alcohol content and temperature in the table.

Alcohol content at different temperatures

Temperature, ° C multiplier to determine the amount of alcohol in its content, the volume fraction

0.96 0.9558 0.95

18.0 0.9620 - 0.9520

17,45 X Y Z

17.0 0.9631 - 0.9530

Find the value of X:

(0.9620-x) / (18,0-17,45) = (0,9620-0,9631) / (18,0-17,0);

X = 0,96126

Calculate the value of Z:

(0,9620 - Z) / (18,0-17,45) = (0,9520-0,9530) / (18,0-17,0);

Z = 0,95255

Find the value of Y:

(0,96261 - Y) / (96,0-95,58) = (0,96261-0,95255) / (96,0-95,0);

Y = 0,96263

Number of waterless ethanol is:

20000 * 0.96263 = 19252.6 l

Запитання для самоперевірки

1. Чим має відрізнятись шкала ареометричного приладу-спиртометра від шкали ареометра-цукрометра?

2. Які фактори можуть впливати на результат вимірів концентрації водно-спиртового розчину?

3. Для чого в спиртометрі є вбудований термометр?

Laboratory work 5

Дата добавления: 2015-11-14