46.80 c.c.

o.1 N I solution required.

The reaction for the sulphurous acid and iodine is

H2SO3 + I2 + H2O = H2SO4 + 2HI.

616. What is the composition of an oleum titrated with phenolphthalein as an indicator, giving the following:

617. A solution shows 0.049205 g. of sulphuric acid per cubic centimeter. How many cubic centimeters of water must be added to a kilogram of this solution to make it 1.000 N?

Ans. 3.36 c.c.

618. How much 0.2019 N sodium hydroxide and water must be taken to make 5 liters of 0.1000 N sodium hydroxide? 1

Ans. 2476.5 c.c. NaOH

2523.5 c.c. H2O

1 Consider the densities of the two liquids and the resultant to be the same in this,

and in other similar problems, unless otherwise mentioned.

619. 50.00 c.c. of a solution (factor to N/10 = 1.005) correspond to 48.90 c.c. of another solution. How many cubic centimeters of water per liter must be added to this second solution to make it N/10? Ans. 27.6 c.c.

620. How many grams each of a 0.5012 N solution must be mixed with a 0.1078 N solution to make one kilogram of a 0.2000 N solution? Ans. 765.6 g. 0.1078 N

234.4 g. 0.5012 N

621. How many pounds of 80.00% acetic acid must be added to 92.60% acetic acid to make 600 lbs. of 90.00% acetic acid?

Ans. 123.8 lbs. 80.00% 476.2 lbs. 92.60%

622. How many pounds of water and how many pounds of 60.00% sulphuric acid must be mixed to prepare 400 lbs. of a 34.20% sulphuric acid? Ans. 228 lbs. 60% H2SO4

172 lbs. water

623. How many pounds of water must be added to 800 pounds of 73.00% sulphuric acid to make the whole 70.00% sulphuric acid? Ans. 34.29 lbs. water

624. How much water must be added to 1000 c.c. of a 0.1128 N solution to make it 0.1000 N? (When the densities of the solutions mixed, and the density of the resultant solution are very nearly the same, as in this case, volumes may be substituted in the formulas without sensible error.)

Ans. 128.00 c.c. water

625. If 0.2605 g. of KH3(C2O4)2 · 2H2O require 59.20 c.c. of a solution to neutralize it and 53.60 c.c. of this solution requires 52.05 c.c. of a hydrochloric acid solution for neutralization, how much water must be added to one liter of the hydrochloric acid solution to make it 0.05000 N? Ans. 69.7 C.C.

626. 45.00 c.c. of a solution of an acid reacts with 1.2000 g. of anhydrous sodium carbonate. How much water should be added to a liter of the solution to make it exactly half normal?

Ans. 6.36 c.c.

627. How many cubic centimeters of a 39.80% solution of hydrochloric acid of specific gravity 1.20 should be taken and diluted to a liter to prepare a N/4 solution?

Ans. 19.10 c.c.

628. It required 48.50 c.c. of a solution of sodium hydroxide to neutralize 0.2134 g. of pure potassium tetroxalate, KH3(C2O4)2⋅ 2H2O. Of this sodium hydroxide solution, 43.19 c.c. were required to neutralize 44.39 c.c. of a solution of hydrochloric acid. How much water must be added to the hydrochloric acid solution to make it just 0.05000 N?

Ans. 10.6 c.c.

629. How many pounds of 62.18% sulphuric acid and of 98.00% sulphuric acid must be taken to make 1000 lbs. of 93.00% acid? Ans. 139.6 lbs. 62.18% H2SO4

860.4 lbs. 98.00 % H2SO4

630. How many pounds of 62.18% sulphuric acid must be added to 1000 lbs. of 98.00% sulphuric acid to dilute the whole to 93.00% acid? Ans. 162.2 lbs. 62.18% H2SO4 631. How much 0.1012 N solution must be added to 1000 c.c. of a 0.5009 N solution to make it 0.2000 N?

Ans. 3045.5 c.c. 0.1012 N 632. How many pounds of 80.00% acetic acid and 60.00% acetic acid should be mixed to make 500 lbs. of 65.00% acetic acid?

1

Ans. 125 lbs. 80% CH3COOH 375 lbs. 60% CH3COOH

633. How many cubic centimeters of 0.0957 N and 0.1120 N solution must be taken to make 1000 c.c. of 0.1000 N solution? (Consider the 0.0957 N solution as being strengthened by the 0.1120 N solution.) Ans. 263.8 c.C. 0.1120 N 736.2 c.c. 0.0957 N

634. How many pounds of 80.00% sulphuric acid must be added to 980 lbs. of 35.00% sulphuric acid to strengthen the whole to 40.00 % acid? Ans. 122.5 lbs. 80% H2SO4

1 In a problem of this kind in which a definite amount is called for, (a) of formula II of page 221 serves as well as (a) of formula III. In one case the formula gives the amount of diluting solution to add; in the other, the amount of strengthening solution required.

635. How many pounds of a 20.00 % hydrochloric acid must be added to 800 lbs. of a 43.00% hydrochloric acid to convert this weight into a 30.00% hydrochloric acid?

Ans. 1040 lbs.

636. How many pounds each of a 30.00% oleum and a 98.00% sulphuric acid must be mixed to prepare 100 lbs. of 100.00% sulphuric acid? (Calculate the percentages of SO3 present in each.)

Ans. 22.83 lbs. 30.00% oleum

77.17 lbs. 98.00 % H2SO4

637. A solution of potassium permanganate is equivalent to 0.01060 g. of Na2C2O4 per cubic centimeter. A weaker solution is equivalent to 0.002120 g. of Na2C2O4 per cubic centimeter. How many cubic centimeters of the stronger solution must be mixed with how many cubic centimeters of the weaker solution to prepare three liters of a solution equivalent to 0.002792 g. of iron per cubic centimeter? Ans. 435 c.c. stronger 2565 c.c. weaker

638. A solution of potassium permanganate is equivalent to 0.005600 g. of iron per cubic centimeter. What volume of this solution and what volume of water must be mixed to prepare three liters of a solution of which each cubic centimeter shall be equivalent to 0.005000 g. of iron? Ans. 2678 c.c. sol. 322 c.c. H2O

639. A solution of sodium hydroxide is equivalent to 0.001000 g. of sulphuric acid per cubic centimeter. How much water must be added to one liter of this solution to make it equivalent to 0.001000 g. of nitric acid per cubic centimeter? Ans. 285 c.c.

CHAPTER X

USE OF SPECIFIC GRAVITY TABLES AND ACID

CALCULATIONS

Calculation of Data in Specific Gravity Tables. - Large shipments of acid, particularly sulphuric acid, are usually billed and paid for on the basis 66° Bé., 60° Bé., etc. It is, therefore, necessary to calculate the actual strength of the acid to its equivalent in 66° Bé., or whatever the strength basis of the acid is billed and paid for.

The table of Ferguson and Talbot1 for sulphuric acid will be used as a model, the same serving as an example of the use of such data. The methods of calculation of the data will be explained, the same being applicable to other solutions, the tables of which have not been so fully arranged.2

Specific gravity tables do not represent individual determinations for the densities listed,3 but are constructed from curves and methods of interpolation already considered.*

Twaddell's Hydrometers consist of a series of hydrometers so arranged that the graduations permit of easy reading over a wide range. They are graduated only for liquids heavier than water. The unit of the Twaddell scale is 0.005 specific gravity; hence if X is the reading Twaddell,

The weight of a cubic foot of water at 60° F. is 62.37 pounds. The weight of a cubic foot of a liquid is its specific gravity multiplied by 62.37.

The acid content corresponding to 66° Bé. (Oil of Vitriol, O. V.) has been carefully ascertained and found to be 93.19% H2SO4. A sample of sulphuric acid of 65.75° Bé. containing 91.80% H2SO4 is equivalent to

1 See Appendix, also Chem. Ann., Table 82.

2 See Chem. Ann., Table 85.

3 The Baumé is given in Ferguson and Talbot's table to two significant figures; it is accurate to two places of decimals.

4 Chap. III.

5 See table of Ferguson and Talbot, Chem. Ann., Table 82, column 3. See also Appendix.